http://www.mdpi.com/journal/pharmaceutics Latest open access articles published in Pharmaceutics at http://www.mdpi.com/journal/pharmaceutics http://www.mdpi.com/1999-4923/4/2/276 New lymphatic imaging technologies are needed to better assess immune function and cancer progression and treatment. Lymphatic uptake depends mainly on particle size (10–100 nm) and charge. The size of carriers for imaging and drug delivery can be optimized to maximize lymphatic uptake, localize chemotherapy to lymphatic metastases, and enable visualization of treatment deposition. Toward this end, female BALB/c mice were injected subcutaneously in the hind footpad or forearm with a series of six different molecular weight hyaluronan (HA) near-infrared dye (HA-IR820) conjugates (ca. 5–200 nm). Mice were imaged using whole body fluorescent imaging over two weeks. HA-IR820 fluorescence was clearly visualized in the draining lymphatic capillaries, and in the popliteal and iliac or axillary lymph nodes. The 74-kDa HA-IR820 had the largest lymph node area-under-the-curve. In contrast to prior reports, mice bearing limb tumors exhibited three-fold longer retention of 74-kDa HA-IR820 in the popliteal node compared to mice without tumors. HA conjugate kinetics and disposition can be specifically tailored by altering their molecular weight. The specific lymphatic uptake and increased nodal retention of HA conjugates indicate significant potential for development as a natural biopolymer for intralymphatic drug delivery and imaging. http://www.mdpi.com/1999-4923/4/2/276 Wed, 23 May 2012 00:00:00 CEST Pharmaceutics 2012-05-23 4 2 Article 276 295 1999-4923 Impact of Molecular Weight on Lymphatic Drainage of a Biopolymer-Based Imaging Agent 2012-05-23 doi: 10.3390/pharmaceutics4020276 Taryn R. Bagby Shuang Cai Shaofeng Duan Sharadvi Thati Daniel J. Aires Laird Forrest http://www.mdpi.com/1999-4923/4/2/252 Several drug delivery systems have been proposed to overcome physiological barriers, improving ocular bioavailability. Systemic routes are seldom used due to the blood-ocular barrier. Novel drug delivery systems based on nanotechnology techniques have been developed to overcome ocular physiological barriers. This non-systematic review suggests the utilization of a transitory blood-ocular breakdown to allow the access of drugs by nanotechnology drug delivery systems via the systemic route. We discuss the possible ways to cause the breakdown of the blood-ocular barrier: acute inflammation caused by intraocular surgery, induced ocular hypotony, and the use of inflammatory mediators. The suitability of use of the systemic route and its toxic effects are also discussed in this article. http://www.mdpi.com/1999-4923/4/2/252 Mon, 14 May 2012 00:00:00 CEST Pharmaceutics 2012-05-14 4 2 Other 252 275 1999-4923 Breakdown of the Blood-Ocular Barrier as a Strategy for the Systemic Use of Nanosystems 2012-05-14 doi: 10.3390/pharmaceutics4020252 Marcelo L. Occhiutto Fatima R. Freitas Raul C. Maranhao Vital P. Costa http://www.mdpi.com/1999-4923/4/1/243 Glaucoma is a progressive optic neuropathy and medical therapy is the initial option for the treatment of this potentially blinding condition. Topical instillation of eye drops from the bottle is the most common glaucoma drug delivery form. Due to limited permeability of anterior ocular surface, natural clearance and drainage, eye drops contain large amounts of inactive ingredients. Effective penetration enhancers are known as irritants causing ocular discomfort. Although drug efficacy is determined by active ingredients, inactive agents can affect tolerance and can result in conjunctival irritation and hyperemia and influence patients’ adherence and quality of life. http://www.mdpi.com/1999-4923/4/1/243 Wed, 21 Mar 2012 00:00:00 CET Pharmaceutics 2012-03-21 4 1 Review 243 251 1999-4923 Ophthalmic Drug Delivery in Glaucoma—A Review 2012-03-21 doi: 10.3390/pharmaceutics4010243 Ingrida Januleviciene Lina Siaudvytyte Ruta Barsauskaite http://www.mdpi.com/1999-4923/4/1/230 Macular edema (ME) is one of the eventual outcomes of various intraocular and systemic pathologies. The pathogenesis for ME is not yet entirely understood; however, some of the common risk factors for its development have been identified. While this investigation will not discuss the numerous etiologies of ME in detail, it appraises the two most widely studied delivery modalities of intraocular corticosteroids in the treatment of ME—intravitreal injection (IVI) and sub-Tenon’s infusion (STI). A thorough review of the medical literature was conducted to identify the efficacy and safety of IVI and STI, specifically for the administration of triamcinolone acetonide (TA), in the setting of ME in an attempt to elucidate a preferred steroid delivery modality for treatment of ME. http://www.mdpi.com/1999-4923/4/1/230 Thu, 15 Mar 2012 00:00:00 CET Pharmaceutics 2012-03-15 4 1 Review 230 242 1999-4923 Delivery of Intraocular Triamcinolone Acetonide in the Treatment of Macular Edema 2012-03-15 doi: 10.3390/pharmaceutics4010230 Aaron Pickrell Alon Harris Sandra Ngo Annahita Amireskandari Erin Stewart Brent Siesky http://www.mdpi.com/1999-4923/4/1/212 The goal of this work was to evaluate tissue-device interactions due to implantation of a mechanically operated drug delivery system onto the posterior sclera. Two test devices were designed and fabricated to model elements of the drug delivery device—one containing a free-spinning ball bearing and the other encasing two articulating gears. Openings in the base of test devices modeled ports for drug passage from device to sclera. Porous poly(tetrafluoroethylene) (PTFE) membranes were attached to half of the gear devices to minimize tissue ingrowth through these ports. Test devices were sutured onto rabbit eyes for 10 weeks. Tissue-device interactions were evaluated histologically and mechanically after removal to determine effects on device function and changes in surrounding tissue. Test devices were generally well-tolerated during residence in the animal. All devices encouraged fibrous tissue formation between the sclera and the device, fibrous tissue encapsulation and invasion around the device, and inflammation of the conjunctiva. Gear devices encouraged significantly greater inflammation in all cases and a larger rate of tissue ingrowth. PTFE membranes prevented tissue invasion through the covered drug ports, though tissue migrated in through other smaller openings. The torque required to turn the mechanical elements increased over 1000 times for gear devices, but only on the order of 100 times for membrane-covered gear devices and less than 100 times for ball bearing devices. Maintaining a lower device profile, minimizing microscale motion on the eye surface and covering drug ports with a porous membrane may minimize inflammation, decreasing the risk of damage to surrounding tissues and minimizing disruption of device operation. http://www.mdpi.com/1999-4923/4/1/212 Mon, 12 Mar 2012 00:00:00 CET Pharmaceutics 2012-03-12 4 1 Article 212 229 1999-4923 Evaluation of Tissue Interactions with Mechanical Elements of a Transscleral Drug Delivery Device 2012-03-12 doi: 10.3390/pharmaceutics4010212 Sarah J. Cohen Robison V. Paul Chan Mark Keegan Christopher M. Andreoli Jeffrey T. Borenstein Joan W. Miller Evangelos S. Gragoudas http://www.mdpi.com/1999-4923/4/1/197 Current glaucoma management modalities are hindered by low patient compliance and adherence. This can be due to highly complex treatment strategies or poor patient understanding. Treatments focus on the management or reduction of intraocular pressure. This is most commonly done through the use of daily topical eye drops. Unfortunately, despite effective therapies, glaucoma continues to progress, possibly due to patients not adhering to their treatments. In order to mitigate these patient compliance issues, many sustained release treatments are being researched and are entering the clinic. Conjunctival, subconjunctival, and intravitreal inserts, punctal plugs, and drug depots are currently in clinical development. Each delivery system has hurdles, yet shows promise and could potentially mitigate the current problems associated with poor patient compliance. http://www.mdpi.com/1999-4923/4/1/197 Thu, 08 Mar 2012 00:00:00 CET Pharmaceutics 2012-03-08 4 1 Review 197 211 1999-4923 Ocular Drug Delivery for Glaucoma Management 2012-03-08 doi: 10.3390/pharmaceutics4010197 Nathan Gooch Sarah A. Molokhia Russell Condie Randon Michael Burr Bonnie Archer Balamurali K. Ambati Barbara Wirostko http://www.mdpi.com/1999-4923/4/1/179 Trimethoprim (TMP) is a dihydrofolate reductase (DHFR) inhibitor which prevents the conversion of dihydrofolic acid into tetrahydrofolic acid, resulting in the depletion of the latter and leading to bacterial death. Oral bioavailability of TMP is hindered by both its low solubility and low permeability. This study aims to prepare novel salts of TMP using anionic amino acids; aspartic and glutamic acid as counter ions in order to improve solubility and dissolution. TMP salts were prepared by lyophilisation and characterized using FT-IR spectroscopy, proton nuclear magnetic resonance (1HNMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). Both the amino acids formed salts with TMP in a 1:1 molar ratio and showed a 280 fold improvement in solubility. Investigation of the microbiological activity of the prepared salts against TMP sensitive Escherichia coli showed that the new salts not only retained antibacterial activity but also exhibited higher zone of inhibition which was attributed to improved physicochemical characters such as higher solubility and dissolution. The results are an important finding that could potentially impact on faster onset of antibacterial activity and reduced therapeutic dose when administered to patients. Studies are underway investigating the effect of ion-pairing TMP with amino acids on the permeability profile of the drug. http://www.mdpi.com/1999-4923/4/1/179 Thu, 16 Feb 2012 00:00:00 CET Pharmaceutics 2012-02-16 4 1 Article 179 196 1999-4923 Preparation and Characterization of Amino Acids-Based Trimethoprim Salts 2012-02-16 doi: 10.3390/pharmaceutics4010179 Amr ElShaer Peter Hanson Tony Worthington Peter Lambert Afzal R. Mohammed http://www.mdpi.com/1999-4923/4/1/164 The objective of this work was to study the polymorphic transformation of carbamazepine from Form II to Form III in 1-propanol during seeded isothermal batch crystallization. First, the pure Form II and Form III were obtained and characterized. Then their solubilities and metastable zone limits were measured by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and focused beam reflectance measurement (FBRM). A transition temperature at about 34.2 °C was deduced suggesting the enantiotropic nature of this compound over the studied temperature range. To quantify the polymorph ratio during the transformation process, a new in-situ quantitative method was developed to measure the fraction of Form II by Raman spectroscopy. Successful tracking of the nucleation of the stable form and the transformation from Form II to Form III during isothermal crystallization was achieved by Raman spectroscopy and FBRM. The results from these three in-situ techniques, FBRM, FTIR and Raman were consistent with each other. The results showed a strong dependency on the amount of seeds added during isothermal crystallization. http://www.mdpi.com/1999-4923/4/1/164 Thu, 09 Feb 2012 00:00:00 CET Pharmaceutics 2012-02-09 4 1 Article 164 178 1999-4923 In Situ Focused Beam Reflectance Measurement (FBRM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Raman Characterization of the Polymorphic Transformation of Carbamazepine 2012-02-09 doi: 10.3390/pharmaceutics4010164 Yingying Zhao Ying Bao Jingkang Wang Sohrab Rohani http://www.mdpi.com/1999-4923/4/1/149 Probiotic encapsulation technology (PET) has the potential to protect microorgansisms and to deliver them into the gut. Because of the promising preclinical and clinical results, probiotics have been incorporated into a range of products. However, there are still many challenges to overcome with respect to the microencapsulation process and the conditions prevailing in the gut. This paper reviews the methodological approach of probiotics encapsulation including biomaterials selection, choice of appropriate technology, in vitro release studies of encapsulated probiotics, and highlights the challenges to be overcome in this area. http://www.mdpi.com/1999-4923/4/1/149 Mon, 06 Feb 2012 00:00:00 CET Pharmaceutics 2012-02-06 4 1 Article 149 163 1999-4923 Probiotic Encapsulation Technology: From Microencapsulation to Release into the Gut 2012-02-06 doi: 10.3390/pharmaceutics4010149 Gildas K. Gbassi Thierry Vandamme http://www.mdpi.com/1999-4923/4/1/130 Gene, short hairpin RNA (shRNA) and small interfering RNA (siRNA) delivery can be particularly used for the treatment of diseases by the entry of genetic materials mammalian cells either to express new proteins or to suppress the expression of proteins, respectively. Polyamidoamine (PAMAM) StarburstTM dendrimers are used as non-viral vectors (carriers) for gene, shRNA and siRNA delivery. Recently, multifunctional PAMAM dendrimers can be used for the wide range of biomedical applications including intracellular delivery of genes and nucleic acid drugs. In this context, this review paper provides the recent findings on PAMAM dendrimer conjugates with cyclodextrins (CyDs) for gene, shRNA and siRNA delivery. http://www.mdpi.com/1999-4923/4/1/130 Wed, 01 Feb 2012 00:00:00 CET Pharmaceutics 2012-02-01 4 1 Review 130 148 1999-4923 Polyamidoamine Dendrimer Conjugates with Cyclodextrins as Novel Carriers for DNA, shRNA and siRNA 2012-02-01 doi: 10.3390/pharmaceutics4010130 Hidetoshi Arima Keiichi Motoyama Taishi Higashi http://www.mdpi.com/1999-4923/4/1/104 This article introduces the formulation of alcohol-free, lecithin microemulsion-based gels (MBGs) prepared with gelatin as gelling agent. The influence of oil, water, lecithin and hydrophilic and lipophilic additives (linkers) on the rheological properties and appearance of these gels was systematically explored using ternary phase diagrams. Clear MBGs were obtained in regions of single phase microemulsions (μEs) at room temperature. Increasing the water content in the formulation increased the elastic modulus of the gels, while increasing the oil content had the opposite effect. The hydrophilic additive (PEG-6-caprylic/capric glycerides) was shown to reduce the elastic modulus of gelatin gels, particularly at high temperatures. In contrast to anionic (AOT) μEs, the results suggest that in lecithin (nonionic) μEs, the introduction of gelatin “dehydrates” the μE. Finally, when the transdermal transport of lidocaine formulated in the parent μE and the resulting MBG were compared, only a minor retardation in the loading and release of lidocaine was observed. http://www.mdpi.com/1999-4923/4/1/104 Tue, 31 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-31 4 1 Article 104 129 1999-4923 Lecithin-Linker Microemulsion Gelatin Gels for Extended Drug Delivery 2012-01-31 doi: 10.3390/pharmaceutics4010104 Xiao-Yue Xuan Yu-Ling Cheng Edgar Acosta http://www.mdpi.com/1999-4923/4/1/93 Amlodipine besilate, a calcium channel antagonist, exists in several solid forms. Processing of anhydrate and dihydrate forms of this drug may lead to solid state changes, and is therefore the focus of this study. Milling was performed for the anhydrate form, whereas the dihydrate form was subjected to quench cooling thereby creating an amorphous form of the drug from both starting materials. The milled and quench cooled samples were, together with the crystalline starting materials, analyzed with X-ray powder diffraction (XRPD), Raman spectroscopy and atomic pair-wise distribution function (PDF) analysis of the XRPD pattern. When compared to XRPD and Raman spectroscopy, the PDF analysis was superior in displaying the difference between the amorphous samples prepared by milling and quench cooling approaches of the two starting materials. http://www.mdpi.com/1999-4923/4/1/93 Tue, 31 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-31 4 1 Article 93 103 1999-4923 Atomic Pairwise Distribution Function Analysis of the Amorphous Phase Prepared by Different Manufacturing Routes 2012-01-31 doi: 10.3390/pharmaceutics4010093 Johan P. Boetker Vishal Koradia Thomas Rades Jukka Rantanen Marja Savolainen http://www.mdpi.com/1999-4923/4/1/71 The stratum corneum is a major barrier of drug penetration across the skin in transdermal delivery. For effective transdermal drug delivery, skin penetration enhancers are used to overcome this barrier. In the past decades, a number of research studies were conducted to understand the mechanisms of skin penetration enhancers and to develop a structure enhancement relationship. Such understanding allows effective prediction of the effects of skin penetration enhancers, assists topical and transdermal formulation development, and avoids extensive enhancer screening in the transdermal delivery industry. In the past two decades, several hypotheses on chemical enhancer-induced penetration enhancement for transport across the skin lipoidal pathway have been examined based on a systematic approach. Particularly, a hypothesis that skin penetration enhancement is directly related to the concentration of the enhancers in the stratum corneum lipid domain was examined. A direct relationship between skin penetration enhancer potency (based on enhancer aqueous concentration in the diffusion cell chamber) and enhancer n-octanol-water partition coefficient was also established. The nature of the microenvironment of the enhancer site of action in the stratum corneum lipid domain was found to be mimicked by n-octanol. The present paper reviews the work related to these hypotheses and the relationships between skin penetration enhancement and enhancer concentration in the drug delivery media and stratum corneum lipids. http://www.mdpi.com/1999-4923/4/1/71 Tue, 17 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-17 4 1 Review 71 92 1999-4923 Structure Enhancement Relationship of Chemical Penetration Enhancers in Drug Transport across the Stratum Corneum 2012-01-17 doi: 10.3390/pharmaceutics4010071 Doungdaw Chantasart S. Kevin Li http://www.mdpi.com/1999-4923/4/1/58 Physical properties of commercial carbamazepine (CBZ) samples can significantly influence drug release and thereby jeopardize bioequivalence of the final dosage form. The aim of this study was to reduce variability in commercial CBZ samples by recrystallization. CBZ samples of four different suppliers were recrystallized in ethanol solution containing 1% polyvinylpyrrolidone (PVP). CBZ samples were analyzed by disk intrinsic dissolution rate (DIDR), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Recrystallized CBZ samples showed strongly reduced variability in DIDR compared to the untreated CBZ samples. Moreover, transformation process to CBZ dihydrate was inhibited; no dihydrate crystals were visible on compact surfaces after 8 h intrinsic dissolution measurement. Recrystallized CBZ samples showed no change in polymorphic form, however, particle size and shape was inhomogenous. In binary mixtures with microcrystalline cellulose, recrystallized CBZ samples again showed difference in drug release. This difference was associated with the inhomogenous particle size in the recrystallized CBZ samples. The results show that a controlled grinding step is required after recrystallization. We suggest the recrystallization in presence of 1% PVP followed by a controlled grinding step as a strategy to reduce dissolution variability in commercial CBZ samples. http://www.mdpi.com/1999-4923/4/1/58 Fri, 13 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-13 4 1 Article 58 70 1999-4923 Recrystallization of Commercial Carbamazepine Samples—A Strategy to Control Dissolution Variability 2012-01-13 doi: 10.3390/pharmaceutics4010058 Felicia Flicker Veronika A. Eberle Gabriele Betz http://www.mdpi.com/1999-4923/4/1/42 Low-molecular-weight heparin/protamine microparticles (LMW-H/P MPs) were produced as a carrier for heparin-binding growth factors (GFs) and for various adhesive cells. A mixture of low-molecular-weight heparin (MW: approximately 5000 Da, 6.4 mg/mL) and protamine (MW: approximately 3000 Da, 10 mg/mL) at a ratio of 7:3 (vol:vol) yields a dispersion of microparticles (0.5–3 µm in diameter). LMW-H/P MPs immobilize, control the release and protect the activity of GFs. LMW-H/P MPs can also bind to cell surfaces, causing these cells to interact with the LMW-H/P MPs, inducing cells/MPs-aggregate formation and substantially promoting cellular viability. Furthermore, LMW-H/P MPs can efficiently bind to tissue culture plates and retain the binding of important GFs, such as fibroblast growth factor (FGF)-2. The LMW-H/P MPs-coated matrix with various GFs or cytokines may provide novel biomaterials that can control cellular activity such as growth and differentiation. Thus, LMW-H/P MPs are an excellent carrier for GFs and various cells and are an efficient coating matrix for cell cultures. http://www.mdpi.com/1999-4923/4/1/42 Wed, 11 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-11 4 1 Review 42 57 1999-4923 Novel Experimental and Clinical Therapeutic Uses of Low-Molecular-Weight Heparin/Protamine Microparticles 2012-01-11 doi: 10.3390/pharmaceutics4010042 Satoko Kishimoto Masayuki Ishihara Megumi Takikawa Yasutaka Mori Hidemi Hattori Masanori Fujita Shingo Nakamura http://www.mdpi.com/1999-4923/4/1/26 Human skin not only serves as an important barrier against the penetration of exogenous substances into the body, but also provides a potential avenue for the transport of functional active drugs/reagents/ingredients into the skin (topical delivery) and/or the body (transdermal delivery). In the past three decades, research and development in human skin equivalents have advanced in parallel with those in tissue engineering and regenerative medicine. The human skin equivalents are used commercially as clinical skin substitutes and as models for permeation and toxicity screening. Several academic laboratories have developed their own human skin equivalent models and applied these models for studying skin permeation, corrosivity and irritation, compound toxicity, biochemistry, metabolism and cellular pharmacology. Various aspects of the state of the art of human skin equivalents are reviewed and discussed. http://www.mdpi.com/1999-4923/4/1/26 Fri, 06 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-06 4 1 Review 26 41 1999-4923 Tissue Engineered Human Skin Equivalents 2012-01-06 doi: 10.3390/pharmaceutics4010026 Zheng Zhang Bozena B. Michniak-Kohn http://www.mdpi.com/1999-4923/4/1/1 During the last decade, the US Food and Drug Administration (FDA) have regulated a wide range of products, (foods, cosmetics, drugs, devices, veterinary, and tobacco) which may utilize micro and nanotechnology or contain nanomaterials. Nanotechnology allows scientists to create, explore, and manipulate materials in nano-regime. Such materials have chemical, physical, and biological properties that are quite different from their bulk counterparts. For pharmaceutical applications and in order to improve their administration (oral, pulmonary and dermal), the nanocarriers can be spread into microparticles. These supramolecular associations can also modulate the kinetic releases of drugs entrapped in the nanoparticles. Different strategies to produce these hybrid particles and to optimize the release kinetics of encapsulated drugs are discussed in this review. http://www.mdpi.com/1999-4923/4/1/1 Fri, 06 Jan 2012 00:00:00 CET Pharmaceutics 2012-01-06 4 1 Review 1 25 1999-4923 Trojan Microparticles for Drug Delivery 2012-01-06 doi: 10.3390/pharmaceutics4010001 Nicolas Anton Anshuman Jakhmola Thierry F. Vandamme http://www.mdpi.com/1999-4923/3/4/954 The objective of the current study was to formulate ketorolac tromethamine-loaded elastic liposomes and evaluate their in vitro drug release and their ex vivo and in vivo transdermal delivery. Ketorolac tromethamine (KT), which is a potent analgesic, was formulated in elastic liposomes using Tween 80 as an edge activator. The elastic vesicles were prepared by film hydration after optimizing the sonication time and number of extrusions. The vesicles exhibited an entrapment efficiency of 73 ± 11%, vesicle size of 127.8 ± 3.4 nm and a zeta potential of −12 mV. In vitro drug release was analyzed from liposomes and an aqueous solution, using Franz diffusion cells and a cellophane dialysis membrane with molecular weight cut-off of 8000 Da. Ex vivo permeation of KT across pig ear skin was studied using a Franz diffusion cell, with phosphate buffer (pH 7.4) at 32 °C as receptor solution. An in vivo drug permeation study was conducted on healthy human volunteers using a tape-stripping technique. The in vitro results showed (i) a delayed release when KT was included in elastic liposomes, compared to an aqueous solution of the drug; (ii) a flux of 0.278 mg/cm2h and a lag time of about 10 h for ex vivo permeation studies, which may indicate that KT remains in the skin (with the possibility of exerting a local effect) before reaching the receptor medium; (iii) a good correlation between the total amount permeated, the penetration distance (both determined by tape stripping) and transepidermal water loss (TEWL) measured during the in vivo permeation studies. Elastic liposomes have the potential to transport the drug through the skin, keep their size and drug charge, and release the drug into deep skin layers. Therefore, elastic liposomes hold promise for the effective topical delivery of KT. http://www.mdpi.com/1999-4923/3/4/954 Thu, 15 Dec 2011 00:00:00 CET Pharmaceutics 2011-12-15 3 4 Article 954 970 1999-4923 Formulation and in Vitro, ex Vivo and in Vivo Evaluation of Elastic Liposomes for Transdermal Delivery of Ketorolac Tromethamine 2011-12-15 doi: 10.3390/pharmaceutics3040954 Guadalupe Nava Elizabeth Piñón Luis Mendoza Néstor Mendoza David Quintanar Adriana Ganem http://www.mdpi.com/1999-4923/3/4/932 Ion channels are involved in a broad range of physiological and pathological processes. The implications of ion channels in a variety of diseases, including diabetes, epilepsy, hypertension, cancer and even chronic pain, have signaled them as pivotal drug targets. Thus far, drugs targeting ion channels were developed without detailed knowledge of the molecular interactions between the lead compounds and the target channels. In recent years, however, the emergence of high-resolution structures for a plethora of ion channels paves the way for computer-assisted drug design. Currently, available functional and structural data provide an attractive platform to generate models that combine substrate-based and protein-based approaches. In silico approaches include homology modeling, quantitative structure-activity relationships, virtual ligand screening, similarity and pharmacophore searching, data mining, and data analysis tools. These strategies have been frequently used in the discovery and optimization of novel molecules with enhanced affinity and specificity for the selected therapeutic targets. In this review we summarize recent applications of in silico methods that are being used for the development of ion channel drugs. http://www.mdpi.com/1999-4923/3/4/932 Fri, 09 Dec 2011 00:00:00 CET Pharmaceutics 2011-12-09 3 4 Review 932 953 1999-4923 Ionic Channels as Targets for Drug Design: A Review on Computational Methods 2011-12-09 doi: 10.3390/pharmaceutics3040932 Gregorio Fernández-Ballester Asia Fernández-Carvajal José Manuel González-Ros Antonio Ferrer-Montiel http://www.mdpi.com/1999-4923/3/4/923 Dosage for the galvanic stimulation for iontophoresis varies. Clinicians manipulate the duration or the amplitude of the current, but it is not known which is more effective. We compared the anesthetic effect of lidocaine HCL (2%) by manipulating the current parameters on 21 healthy volunteers (age: 21.2 ± 4.2, height 170.7 ± 10.2 cm, mass 82.1 ± 19.2 kg). Three conditions were administered in a random order using a Phoresor II® with 2 mL, 2% lidocaine HCL in an iontophoresis electrode. (1) HASD (40 mA*min): High amplitude (4 mA), short duration (10 min); (2) LALD (40 mA.min): Low amplitude (2 mA), long duration (20 min); (3) Sham condition (0 mA, 20 min). Semmes-Weinstein monofilament (SWM) scores were taken pre and post intervention to measure sensation changes. Two-way ANOVA with repeated measures was used to compare sensation. Both iontophoresis treatments: LALD (4.2 ± 0.32 mm) and HASD (4.2 ± 0.52 mm) significantly increased SWM scores, indicating an increase in anesthesia, compared to the sham condition (3.6 ± 0.06 mm) p < 0.05. Neither LALD nor HASD was more effective and there was no difference in anesthesia with the sham. Lidocaine delivered via iontophoresis reduces cutaneous sensation. However, there was no benefit in either a HASD or LALD treatment. http://www.mdpi.com/1999-4923/3/4/923 Tue, 06 Dec 2011 00:00:00 CET Pharmaceutics 2011-12-06 3 4 Article 923 931 1999-4923 Effect of Duration and Amplitude of Direct Current when Lidocaine Is Delivered by Iontophoresis 2011-12-06 doi: 10.3390/pharmaceutics3040923 Susan A. Saliba Courtney L. Teeter-Heyl Patrick McKeon Christopher D. Ingeroll Ethan N. Saliba http://www.mdpi.com/1999-4923/3/4/914 Most patents covering dermatologic products contain patent claims directed to the pharmaceutical formulation of the product. Such patents, known as formulation patents, are vulnerable to attacks based on the legal argument that the formulations covered are obvious over formulations already known prior to the filing of the patent application. Because obviousness is an important concept in patent law, recent court cases concerning obviousness and formulation patents were examined and discussed below. Courts have ruled that patent claims are obvious when features of the claimed formulation are found in the prior art, even if the features or characteristics of the formulation are not explicitly disclosed in the prior art. However, patentees have successfully overcome obviousness challenges where there were unexpected results or properties and/or the prior art taught away from the claimed invention. http://www.mdpi.com/1999-4923/3/4/914 Mon, 21 Nov 2011 00:00:00 CET Pharmaceutics 2011-11-21 3 4 Article 914 922 1999-4923 Formulation Patents and Dermatology and Obviousness 2011-11-21 doi: 10.3390/pharmaceutics3040914 Dan-Feng Mei Josephine Liu Michael A. Davitz http://www.mdpi.com/1999-4923/3/4/865 Like any other drug, antimicrobial drugs are prone to pharmacokinetic drug interactions. These drug interactions are a major concern in clinical practice as they may have an effect on efficacy and toxicity. This article provides an overview of all published pharmacokinetic studies on drug interactions of the commonly prescribed antimicrobial drugs oxazolidinones, rifamycines, macrolides, fluoroquinolones, and beta-lactams, focusing on systematic research. We describe drug-food and drug-drug interaction studies in humans, affecting antimicrobial drugs as well as concomitantly administered drugs. Since knowledge about mechanisms is of paramount importance for adequate management of drug interactions, the most plausible underlying mechanism of the drug interaction is provided when available. This overview can be used in daily practice to support the management of pharmacokinetic drug interactions of antimicrobial drugs. http://www.mdpi.com/1999-4923/3/4/865 Fri, 18 Nov 2011 00:00:00 CET Pharmaceutics 2011-11-18 3 4 Review 865 913 1999-4923 Pharmacokinetic Drug Interactions of Antimicrobial Drugs: A Systematic Review on Oxazolidinones, Rifamycines, Macrolides, Fluoroquinolones, and Beta-Lactams 2011-11-18 doi: 10.3390/pharmaceutics3040865 Mathieu S. Bolhuis Prashant N. Panday Arianna D. Pranger Jos G. W. Kosterink Jan-Willem C. Alffenaar http://www.mdpi.com/1999-4923/3/4/848 Whilst there is a large body of evidence looking at the design of cationic liposomes as transfection agents, correlates of formulation to function remain elusive. In this research, we investigate if lipid packaging can give further insights into transfection efficacy. DNA lipoplexes composed of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) in combination with 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or 1,2-stearoyl-3-trimethylammonium-propane (DSTAP) were prepared by the lipid hydration method. Each of the formulations was prepared by hydration in dH2O or phosphate buffer saline (PBS) to investigate the effect of buffer salts on lipoplex physicochemical characteristics and in vitro transfection. In addition, Langmuir monolayer studies were performed to investigate any possible correlation between lipid packaging and liposome attributes. Using PBS, rather than dH2O, to prepare the lipoplexes increased the size of vesicles in most of formulations and resulted in variation in transfection efficacies. However, one combination of lipids (DSPE:DOTAP) could not form liposomes in PBS, whilst the DSPE:DSTAP combination could not form liposomes in either aqueous media. Monolayer studies demonstrated saturated lipid combinations offered dramatically closer molecular packing compared to the other combinations which could suggest why this lipid combination could not form vesicles. Of the lipoplexes prepared, those formulated with DSTAP showed higher transfection efficacy, however, the effect of buffer on transfection efficiency was formulation dependent. http://www.mdpi.com/1999-4923/3/4/848 Fri, 18 Nov 2011 00:00:00 CET Pharmaceutics 2011-11-18 3 4 Article 848 864 1999-4923 Exploring the Correlation Between Lipid Packaging in Lipoplexes and Their Transfection Efficacy 2011-11-18 doi: 10.3390/pharmaceutics3040848 Behfar Moghaddam Sarah E. McNeil Qinguo Zheng Afzal R. Mohammed Yvonne Perrie http://www.mdpi.com/1999-4923/3/4/830 The objectives of this work were the formulation optimization of the preparation process parameters and to evaluate spray-dried sustained-release microspheres using ammonio methacrylate copolymer (AMC) as a polymer matrix. The effects of log P and the concentrations of the cosolvents (acetone, methyl ethyl ketone and n-butyl acetate) and different drug/copolymer ratios as independent variables on the physicochemical parameters (the W1/O emulsion viscosity, the microsphere production yield, the average particle size, the encapsulation efficiency) and the cumulative in vitro drug release as dependent variables were studied. The optimization was carried out on the basis of the 33 factorial design study. The optimization process results showed that addition of polar cosolvents proved effective, linear relationships were observed between the independent and the dependent variables. The best conditions were achieved by microspheres prepared by using a low/medium cosolvent log P, cosolvent concentration of 25–50% v/v and a drug/copolymer ratio of 1:16. The microspheres ensured sustained release with Nernst and Baker-Lonsdale release profiles. http://www.mdpi.com/1999-4923/3/4/830 Thu, 10 Nov 2011 00:00:00 CET Pharmaceutics 2011-11-10 3 4 Article 830 847 1999-4923 Formulation Optimization of Sustained-Release Ammonio Methacrylate Copolymer Microspheres. Effects of Log P and Concentration of Polar Cosolvents, and Role of the Drug/Copolymer Ratio 2011-11-10 doi: 10.3390/pharmaceutics3040830 Péter Sipos Róbert Rajkó Klára Pintye-Hódi István Erős Piroska Szabó-Révész http://www.mdpi.com/1999-4923/3/4/793 Natural polyphenols are valuable compounds possessing scavenging properties towards radical oxygen species, and complexing properties towards proteins. These abilities make polyphenols interesting for the treatment of various diseases like inflammation or cancer, but also for anti-ageing purposes in cosmetic formulations, or for nutraceutical applications. Unfortunately, these properties are also responsible for a lack in long-term stability, making these natural compounds very sensitive to light and heat. Moreover, polyphenols often present a poor biodisponibility mainly due to low water solubility. Lastly, many of these molecules possess a very astringent and bitter taste, which limits their use in food or in oral medications. To circumvent these drawbacks, delivery systems have been developed, and among them, encapsulation would appear to be a promising approach. Many encapsulation methods are described in the literature, among which some have been successfully applied to plant polyphenols. In this review, after a general presentation of the large chemical family of plant polyphenols and of their main chemical and biological properties, encapsulation processes applied to polyphenols are classified into physical, physico-chemical, chemical methods, and other connected stabilization methods. After a brief description of each encapsulation process, their applications to polyphenol encapsulation for pharmaceutical, food or cosmetological purposes are presented. http://www.mdpi.com/1999-4923/3/4/793 Fri, 04 Nov 2011 00:00:00 CET Pharmaceutics 2011-11-04 3 4 Review 793 829 1999-4923 Encapsulation of Natural Polyphenolic Compounds; a Review 2011-11-04 doi: 10.3390/pharmaceutics3040793 Aude Munin Florence Edwards-Lévy http://www.mdpi.com/1999-4923/3/4/782 P-glycoprotein (P-gp) is an ATP-dependent transporter localized at the apical membrane of the kidney proximal tubules, which plays a role in the efflux of cationic and amphipathic endogenous waste products and xenobiotics, such as drugs, into urine. Studies in mice deficient in P-gp showed generalized proximal tubular dysfunction similar to the phenotype of patients with cystinosis, an autosomal recessive disorder caused by mutations in the lysosomal cystine transporter cystinosin. Renal disease in cystinosis is characterized by generalized dysfunction of the apical proximal tubular influx transporters (so-called renal Fanconi syndrome) developing during infancy and gradually progressing towards end-stage renal disease before the 10th birthday in the majority of patients that are not treated with the cystine-depleting drug cysteamine. Here, we investigated whether the proximal tubular efflux transporter P-gp is affected in cystinosis and whether this might contribute to the development of renal Fanconi syndrome. We used conditionally immortalized (ci) proximal tubular epithelial cells (ciPTEC) derived from cystinotic patients and healthy volunteers. P-gp-mediated transport was measured by using the P-gp substrate calcein-AM in the presence and absence of the P-gp-inhibitor PSC833. P-gp activity was normal in cystinotic cells as compared to controls. Additionally, the effect of cysteamine on P-gp transport activity and phosphate uptake was determined; demonstrating increased P-gp activity in cystinotic cells, and further decrease of proximal tubular phosphate uptake. This observation is compatible with the persistence of renal Fanconi syndrome in vivo under cysteamine therapy. In summary, P-gp expression and activity are normal in cystinotic ciPTEC, indicating that P-gp dysfunction is not involved in the pathogenesis of cystinosis. http://www.mdpi.com/1999-4923/3/4/782 Thu, 27 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-27 3 4 Article 782 792 1999-4923 Role of P-Glycoprotein Expression and Function in Cystinotic Renal Proximal Tubular Cells 2011-10-27 doi: 10.3390/pharmaceutics3040782 Karen Peeters Martijn J. Wilmer Joost P. Schoeber Dorien Reijnders Lambertus P. van den Heuvel Rosalinde Masereeuw Elena Levtchenko http://www.mdpi.com/1999-4923/3/4/745 Antiretrovirals are prone to drug-drug and drug-food interactions that can result in subtherapeutic or supratherapeutic concentrations. Interactions between antiretrovirals and medications for other diseases are common due to shared metabolism through cytochrome P450 (CYP450) and uridine diphosphate glucuronosyltransferase (UGT) enzymes and transport by membrane proteins (e.g., p-glycoprotein, organic anion-transporting polypeptide). The clinical significance of antiretroviral drug interactions is reviewed, with a focus on new and investigational agents. An overview of the mechanistic basis for drug interactions and the effect of individual antiretrovirals on CYP450 and UGT isoforms are provided. Interactions between antiretrovirals and medications for other co-morbidities are summarized. The role of therapeutic drug monitoring in the detection and management of antiretroviral drug interactions is also briefly discussed. http://www.mdpi.com/1999-4923/3/4/745 Fri, 21 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-21 3 4 Review 745 781 1999-4923 Antiretroviral Drug Interactions: Overview of Interactions Involving New and Investigational Agents and the Role of Therapeutic Drug Monitoring for Management 2011-10-21 doi: 10.3390/pharmaceutics3040745 R. Chris Rathbun Michelle D. Liedtke http://www.mdpi.com/1999-4923/3/4/731 The objectives of this study were to investigate the feasibility of encapsulating yeast cells using gellan gum by an emulsification method and to evaluate the fermentation efficiency and the reusability of the micro-bioreactors produced. It was found that yeast cells could be successfully encapsulated to form relatively spherical micro-bioreactors with high specific surface area for mass transfer. Cell viability was found to be reduced by one log reduction after the emulsification process. The ethanol yield of the micro-bioreactors was comparable to that of free yeast in the first fermentation cycle. The micro-bioreactors remained intact and could be re-used up to 10 cycles of fermentation. Despite cell breakthrough, relatively high ethanol yields were obtained, indicating that the micro-bioreactors also functioned as regenerative reservoirs of yeast. http://www.mdpi.com/1999-4923/3/4/731 Mon, 17 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-17 3 4 Article 731 744 1999-4923 Development of Re-Usable Yeast-Gellan Gum Micro-Bioreactors for Potential Application in Continuous Fermentation to Produce Bio-Ethanol 2011-10-17 doi: 10.3390/pharmaceutics3040731 Sook Mun Tan Paul Wan Sia Heng Lai Wah Chan http://www.mdpi.com/1999-4923/3/4/723 Background: Active coating is an important unit operation in the pharmaceutical industry. The quality, stability, safety and performance of the final product largely depend on the amount and uniformity of coating applied. Active coating is challenging regarding the total amount of coating and its uniformity. Consequently, there is a strong demand for tools, which are able to monitor and determine the endpoint of a coating operation. In previous work, it was shown that Raman spectroscopy is an appropriate process analytical tool (PAT) to monitor an active spray coating process in a pan coater [1]. Using a multivariate model (Partial Least Squares—PLS) the Raman spectral data could be correlated with the coated amount of the API diprophylline. While the multivariate model was shown to be valid for the process in a mini scale pan coater (batch size: 3.5 kg cores), the aim of the present work was to prove the robustness of the model by transferring the results to tablets coated in a micro scale pan coater (0.5 kg). Method: Coating experiments were performed in both, a mini scale and a micro scale pan coater. The model drug diprophylline was coated on placebo tablets. The multivariate model, established for the process in the mini scale pan coater, was applied to the Raman measurements of tablets coated in the micro scale coater for six different coating levels. Then, the amount of coating, which was predicted by the model, was compared with reference measurements using UV spectroscopy. Results: For all six coating levels the predicted coating amount was equal to the amounts obtained by UV spectroscopy within the statistical error. Thus, it was possible to predict the total coating amount with an error smaller than 3.6%. The root mean squares of errors for calibration and prediction (root mean square of errors for calibration and prediction—RMSEC and RMSEP) were 0.335 mg and 0.392 mg, respectively, which means that the predictive power of the model is not dependent on the scale or the equipment. Conclusion: The scale-down experiment showed that it was possible to transfer the PLS model developed on a mini scale coater to a micro scale coater. http://www.mdpi.com/1999-4923/3/4/723 Fri, 14 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-14 3 4 Article 723 730 1999-4923 From Mini to Micro Scale—Feasibility of Raman Spectroscopy as a Process Analytical Tool (PAT) 2011-10-14 doi: 10.3390/pharmaceutics3040723 Markus Wirges Joshua Müller Péter Kása Géza Regdon Klára Pintye-Hódi Klaus Knop Peter Kleinebudde http://www.mdpi.com/1999-4923/3/4/706 Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e.,piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form of the piracetam and no polymorphic cocrystals were obtained. http://www.mdpi.com/1999-4923/3/4/706 Wed, 12 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-12 3 4 Article 706 722 1999-4923 Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding 2011-10-12 doi: 10.3390/pharmaceutics3040706 Sönke Rehder Marten Klukkert Korbinian A. M. Löbmann Clare J. Strachan Albrecht Sakmann Keith Gordon Thomas Rades Claudia S. Leopold http://www.mdpi.com/1999-4923/3/4/680 Uptake transporters (e.g., members of the SLC superfamily of solute carriers) and export proteins (e.g., members of the ABC transporter superfamily) are important determinants for the pharmacokinetics of drugs. Alterations of drug transport due to concomitantly administered drugs that interfere with drug transport may alter the kinetics of drug substrates. In vitro and in vivo studies indicate that many drugs used for the treatment of metabolic disorders and cardiovascular diseases (e.g., oral antidiabetic drugs, statins) are substrates for uptake transporters and export proteins expressed in the intestine, the liver and the kidney. Since most patients with type 2 diabetes receive more than one drug, transporter-mediated drug-drug interactions are important molecular mechanisms leading to alterations in oral antidiabetic drug pharmacokinetics with the risk of adverse drug reactions. This review focuses on uptake transporters of the SLCO/SLC21 (OATP) and SLC22 (OCT/OAT) family of solute carriers and export pumps of the ABC (ATP-binding cassette) transporter superfamily (especially P-glycoprotein) as well as the export proteins of the SLC47 (MATE) family and their role for transporter-mediated drug-drug interactions with oral antidiabetic drugs. http://www.mdpi.com/1999-4923/3/4/680 Wed, 12 Oct 2011 00:00:00 CEST Pharmaceutics 2011-10-12 3 4 Review 680 705 1999-4923 Transporter-Mediated Drug–Drug Interactions with Oral Antidiabetic Drugs 2011-10-12 doi: 10.3390/pharmaceutics3040680 Sabine Klatt Martin F. Fromm Jörg König http://www.mdpi.com/1999-4923/3/4/665 This study describes the in vitro/ex vivo buccal release of chlorhexidine (CHX) from nine mucoadhesive aqueous gels, as well as their physicochemical and mucoadhesive properties: CHX was present at a constant 1% w/v concentration in the chemical form of digluconate salt. The mucoadhesive/gel forming materials were carboxymethyl- (CMC), hydroxypropylmethyl- (HPMC) and hydroxypropyl- (HPC) cellulose, alone (3% w/w) or in binary mixtures (5% w/w); gels were tested for their mucoadhesion using the mucin method at 1, 2 and 3% w/w concentrations. CHX release from different formulations was assessed using a USP method and newly developed apparatus, combining release/permeation process in which porcine mucosa was placed in a Franz cell. The combination of HPMC or HPC with CMC showed slower drug release when compared to each of the individual polymers. All the systems proved suitable for CHX buccal delivery, being able to guarantee both prolonged release and reduced transmucosal permeation. Gels were compared for the release of previously studied tablets that contained Carbopol and HPMC, alone or in mixture. An accurate selection and combination of the materials allow the design of different pharmaceutical forms suitable for different purposes, by simply modifying the formulation compositions. http://www.mdpi.com/1999-4923/3/4/665 Tue, 27 Sep 2011 00:00:00 CEST Pharmaceutics 2011-09-27 3 4 Article 665 679 1999-4923 Mucoadhesive Gels Designed for the Controlled Release of Chlorhexidine in the Oral Cavity 2011-09-27 doi: 10.3390/pharmaceutics3040665 Adamo Fini Valentina Bergamante Gian Carlo Ceschel http://www.mdpi.com/1999-4923/3/3/636 Bicellar systems are lipid nanostructures formed by long- and short-chained phospholipids dispersed in aqueous solution. The morphological transitions of bicellar aggregates due to temperature, composition and time variations have been revised in this work. To this end, two bicellar systems have been considered; one formed by dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl- phosphatidylcholine (DHPC) and another formed by dipalmitoyl-phosphatidylcholine (DPPC) and DHPC. The relationship between the magnetic alignment, the morphology of the aggregates and the phase transition temperature (Tm) of lipids is discussed. In general terms, the non-alignable samples present rounded objects at temperature below the Tm. Above this temperature, an increase of viscosity is followed by the formation of large elongated aggregates. Alignable samples presented discoidal objects below the Tm. The best alignment was achieved above this temperature with large areas of lamellar stacked bilayers and some multilamellar vesicles. The effect of the inclusion of ceramides with different chain lengths in the structure of bicelles is also revised in the present article. A number of physical techniques show that the bicellar structures are affected by both the concentration and the type of ceramide. Systems are able to incorporate 10% mol of ceramides that probably are organized forming domains. The addition of 20% mol of ceramides promotes destabilization of bicelles, promoting the formation of mixed systems that include large structures. Bicellar systems have demonstrated to be morphologically stable with time, able to encapsulate different actives and to induce specific effects on the skin. These facts make bicellar systems good candidates as colloidal carriers for dermal delivery. However, water dilution induces structural changes and formation of vesicular structures in the systems; stabilization strategies have been been explored in recent works and are also updated here. http://www.mdpi.com/1999-4923/3/3/636 Wed, 14 Sep 2011 00:00:00 CEST Pharmaceutics 2011-09-14 3 3 Review 636 664 1999-4923 Structural Versatility of Bicellar Systems and Their Possibilities as Colloidal Carriers 2011-09-14 doi: 10.3390/pharmaceutics3030636 Barbosa-Barros Lucyanna Rodríguez Gelen Cócera Merce Rubio Laia López-Iglesias Carmen de la Maza Alfons López Olga http://www.mdpi.com/1999-4923/3/3/615 Photodynamic diagnosis (PDD) is a practical tool currently used in surgical operation of aggressive brain tumors, such as glioblastoma. PDD is achieved by a photon-induced physicochemical reaction which is induced by excitation of protoporphyrin IX (PpIX) exposed to light. Fluorescence-guided gross-total resection has recently been developed in PDD, where 5-aminolevulinic acid (ALA) or its ester is administered as the precursor of PpIX. ALA induces the accumulation of PpIX, a natural photo-sensitizer, in cancer cells. Recent studies provide evidence that adenosine triphosphate (ATP)-binding cassette (ABC) transporter ABCG2 plays a pivotal role in regulating the cellular accumulation of porphyrins in cancer cells and thereby affects the efficacy of PDD. Protein kinase inhibitors are suggested to potentially enhance the PDD efficacy by blocking ABCG2-mediated porphyrin efflux from cancer cells. It is of great interest to develop potent ABCG2-inhibitors that can be applied to PDD for brain tumor therapy. This review article addresses a pivotal role of human ABC transporter ABCG2 in PDD as well as a new approach of quantitative structure-activity relationship (QSAR) analysis to design potent ABCG2-inhibitors. http://www.mdpi.com/1999-4923/3/3/615 Wed, 14 Sep 2011 00:00:00 CEST Pharmaceutics 2011-09-14 3 3 Review 615 635 1999-4923 Transporter-Mediated Drug Interaction Strategy for 5-Aminolevulinic Acid (ALA)-Based Photodynamic Diagnosis of Malignant Brain Tumor: Molecular Design of ABCG2 Inhibitors 2011-09-14 doi: 10.3390/pharmaceutics3030615 Toshihisa Ishikawa Kenkichi Takahashi Naokado Ikeda Yoshinaga Kajimoto Yuichiro Hagiya Shun-ichiro Ogura Shin-ichi Miyatake Toshihiko Kuroiwa http://www.mdpi.com/1999-4923/3/3/601 In the pharmaceutical industry, co-crystals are becoming increasingly valuable as crystalline solids that can offer altered/improved physical properties of an active pharmaceutical ingredient (API) without changing its chemical identity or biological activity. In order to identify new solid forms of diclofenac—an analgesic with extremely poor aqueous solubility for which few co-crystal structures have been determined—a range of pyrazoles, pyridines, and pyrimidines were screened for co-crystal formation using solvent assisted grinding and infrared spectroscopy with an overall success rate of 50%. The crystal structures of three new diclofenac co-crystals are reported herein: (diclofenac)∙(2-aminopyrimidine), (diclofenac)∙(2-amino-4,6-dimethylpyrimidine), and (diclofenac)∙(2-amino-4-chloro-6-methylpyrimidine). http://www.mdpi.com/1999-4923/3/3/601 Wed, 31 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-31 3 3 Article 601 614 1999-4923 Co-Crystal Screening of Diclofenac 2011-08-31 doi: 10.3390/pharmaceutics3030601 Christer B. Aakeröy Angela B. Grommet John Desper http://www.mdpi.com/1999-4923/3/3/582 The application of twin screw extrusion (TSE) as a scalable and green process for the manufacture of cocrystals was investigated. Four model cocrystal forming systems, Caffeine-Oxalic acid, Nicotinamide-trans cinnamic acid, Carbamazepine-Saccharin, and Theophylline-Citric acid, were selected for the study. The parameters of the extrusion process that influenced cocrystal formation were examined. TSE was found to be an effective method to make cocrystals for all four systems studied. It was demonstrated that temperature and extent of mixing in the extruder were the primary process parameters that influenced extent of conversion to the cocrystal in neat TSE experiments. In addition to neat extrusion, liquid-assisted TSE was also demonstrated for the first time as a viable process for making cocrystals. Notably, the use of catalytic amount of benign solvents led to a lowering of processing temperatures required to form the cocrystal in the extruder. TSE should be considered as an efficient, scalable, and environmentally friendly process for the manufacture of cocrystals with little to no solvent requirements. http://www.mdpi.com/1999-4923/3/3/582 Wed, 31 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-31 3 3 Article 582 600 1999-4923 Application of Twin Screw Extrusion in the Manufacture of Cocrystals, Part I: Four Case Studies 2011-08-31 doi: 10.3390/pharmaceutics3030582 Dominick Daurio Cesar Medina Robert Saw Karthik Nagapudi Fernando Alvarez-Núñez http://www.mdpi.com/1999-4923/3/3/572 Orbifloxacin is a fluoroquinolone with broad-spectrum antimicrobial activity, and belongs to the third generation of quinolones. Regarding the quality control of medicines, a validated microbiological assay for determination of orbifloxacin in pharmaceutical formulations has not as yet been reported. For this purpose, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method to quantify orbifloxacin in tablet formulations. The assay is based on the inhibitory effect of orbifloxacin upon the strain of Staphylococcus aureus ATCC 25923 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.9992) in the selected range of 16.0–64.0 μg/mL, precise with relative standard deviation (RSD) of repeatability intraday = 2.88%, intermediate precision RSD = 3.33%, and accurate (100.31%). The results demonstrated the validity of the proposed bioassay, which allows reliable orbifloxacin quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine. http://www.mdpi.com/1999-4923/3/3/572 Mon, 29 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-29 3 3 Article 572 581 1999-4923 Development and Validation of a Microbiological Agar Assay for Determination of Orbifloxacin in Pharmaceutical Preparations 2011-08-29 doi: 10.3390/pharmaceutics3030572 Edith C. L. Cazedey Hérida R. N. Salgado http://www.mdpi.com/1999-4923/3/3/538 In the treatment of intracanal and periodontal infections, the local application of antibiotics and other therapeutic agents in the root canal or in periodontal pockets may be a promising approach to achieve sustained drug release, high antimicrobial activity and low systemic side effects. Microparticles made from biodegradable polymers have been reported to be an effective means of delivering antibacterial drugs in endodontic and periodontal therapy. The aim of this review article is to assess recent therapeutic strategies in which biocompatible microparticles are used for effective management of periodontal and endodontic diseases. In vitro and in vivo studies that have investigated the biocompatibility or efficacy of certain microparticle formulations and devices are presented. Future directions in the application of microencapsulation techniques in endodontic and periodontal therapies are discussed. http://www.mdpi.com/1999-4923/3/3/538 Fri, 26 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-26 3 3 Review 538 571 1999-4923 The Application of Microencapsulation Techniques in the Treatment of Endodontic and Periodontal Diseases 2011-08-26 doi: 10.3390/pharmaceutics3030538 Asteria Luzardo Álvarez Francisco Otero Espinar José Blanco Méndez http://www.mdpi.com/1999-4923/3/3/525 This manuscript studied the effect of counterion on the glass transition and recrystallization behavior of amorphous salts of prazosin. Three amorphous salts of prazosin, namely, prazosin hydrochloride, prazosin mesylate and prazosin tosylate were prepared by spray drying, and characterized by optical-polarized microscopy, differential scanning calorimetry and powder X-ray diffraction. Modulated differential scanning calorimetry was used to determine the glass transition and recrystallization temperature of amorphous salts. Glass transition of amorphous salts followed the order: prazosin mesylate > prazosin tosylate ~ prazosin hydrochloride. Amorphous prazosin mesylate and prazosin tosylate showed glass transition, followed by recrystallization. In contrast, amorphous prazosin hydrochloride showed glass transition and recrystallization simultaneously. Density Functional Theory, however, suggested the expected order of glass transition as prazosin hydrochloride > prazosin mesylate > prazosin tosylate. The counterintuitive observation of amorphous prazosin hydrochloride having lower glass transition was explained in terms of its lower activation energy (206.1 kJ/mol) for molecular mobility at Tg, compared to that for amorphous prazosin mesylate (448.5 kJ/mol) and prazosin tosylate (490.7 kJ/mol), and was further correlated to a difference in hydrogen bonding strength of the amorphous and the corresponding recrystallized salts. This study has implications in selection of an optimal amorphous salt form for pharmaceutical development. http://www.mdpi.com/1999-4923/3/3/525 Thu, 25 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-25 3 3 Article 525 537 1999-4923 Investigation of the Atypical Glass Transition and Recrystallization Behavior of Amorphous Prazosin Salts 2011-08-25 doi: 10.3390/pharmaceutics3030525 Lokesh Kumar Dharmesh Popat Arvind K. Bansal http://www.mdpi.com/1999-4923/3/3/510 The aim of the present study was to investigate the influence of process shear stressors on the stability of a model monoclonal antibody, trastuzumab. Trastuzumab, at concentrations of 0.4–4.0 mg/mL, was subjected to sonication, freeze-thaw, lyophilisation, spray drying and was encapsulated into micro- and nanoparticles. The stressed samples were analysed for structural integrity by gel electrophoresis, SDS-PAGE, and size exclusion chromatography (SEC), while the conformational integrity was analysed by circular dichroism (CD). Biological activity of the stressed trastuzumab was investigated by measuring the inhibition of cell proliferation of HER-2 expressing cell lines. Results show that trastuzumab was resistant to the process shear stresses applied and to microencapsulation processes. At the lowest concentration of 0.4 mg/mL, a low percent ( 0.05). The results of this study conclude that trastuzumab may be resistant to various processing stresses. These findings have important implications with respect to pharmaceutical processing of monoclonal antibodies. http://www.mdpi.com/1999-4923/3/3/510 Wed, 24 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-24 3 3 Article 510 524 1999-4923 Effect of Microencapsulation Shear Stress on the Structural Integrity and Biological Activity of a Model Monoclonal Antibody, Trastuzumab 2011-08-24 doi: 10.3390/pharmaceutics3030510 Ritesh M. Pabari Benedict Ryan Catherine McCarthy Zebunnissa Ramtoola http://www.mdpi.com/1999-4923/3/3/497 Quercetin (3,3′,4′,5,7-pentahydroxyflavone) exerts multiple pharmacological effects: anti-oxidant activity, induction of apoptosis, modulation of cell cycle, anti-mutagenesis, and anti-inflammatory effect. In topical formulations quercetin inhibits oxidative skin damage and the inflammatory processes induced by solar UV radiation. In this work, quercetin (2 mg/mL) was loaded in vesicular Penetration Enhancer containing Vesicles (PEVs), prepared using a mixture of lipids (Phospholipon® 50, P50) and one of four selected hydrophilic penetration enhancers: Transcutol® P, propylene glycol, polyethylene glycol 400, and Labrasol® at the same concentration (40% of water phase). Photon Correlation Spectroscopy results showed a mean diameter of drug loaded vesicles in the range 80–220 nm. All formulations showed a negative surface charge and incorporation efficiency in the range 48–75%. Transmission Electron Microscopy confirmed that size and morphology varied as a function of the used penetration enhancer. The influence of PEVs on ex vivo quercetin (trans)dermal delivery was evaluated using Franz-type diffusion cells, new born pig skin and Confocal Laser Scanning Microscopy. Results showed that drug delivery is affected by the penetration enhancer used in the PEVs' formulation. http://www.mdpi.com/1999-4923/3/3/497 Fri, 12 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-12 3 3 Article 497 509 1999-4923 Effect of Penetration Enhancer Containing Vesicles on the Percutaneous Delivery of Quercetin through New Born Pig Skin 2011-08-12 doi: 10.3390/pharmaceutics3030497 Maura Chessa Carla Caddeo Donatella Valenti Maria Manconi Chiara Sinico Anna Maria Fadda http://www.mdpi.com/1999-4923/3/3/485 Abstract: The dynamic performances of two different controlled-release systems were analyzed. In a reservoir-type drug-delivery patch, the transdermal flux is influenced by the properties of the membrane. A constant thermodynamic drug activity is preserved in the donor compartment. Monolithic matrices are among the most inexpensive systems used to direct drug delivery. In these structures, the active pharmaceutical ingredients are encapsulated within a polymeric material. Despite the popularity of these two devices, to tailor the properties of the polymer and additives to specific transient behaviors can be challenging and time-consuming. The heuristic approaches often considered to select the vehicle formulation provide limited insight into key permeation mechanisms making it difficult to predict the device performance. In this contribution, a method to calculate the flux response time in a system consisting of a reservoir and a polymeric membrane was proposed and confirmed. Nearly 8.60 h passed before the metoprolol delivery rate reached ninety-eight percent of its final value. An expression was derived for the time it took to transport the active pharmaceutical ingredient out of the polymer. Ninety-eight percent of alpha-tocopherol acetate was released in 461.4 h following application to the skin. The effective time constant can be computed to help develop optimum design strategies. http://www.mdpi.com/1999-4923/3/3/485 Thu, 11 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-11 3 3 Article 485 496 1999-4923 A Computational Procedure for Assessing the Dynamic Performance of Diffusion-Controlled Transdermal Delivery Devices 2011-08-11 doi: 10.3390/pharmaceutics3030485 Laurent Simon http://www.mdpi.com/1999-4923/3/3/474 Vitamin B12 deficiency, which may result in anemia and nerve damage if left untreated, is currently treated by administration of cyanocobalamin via oral or intramuscular routes. However, these routes are associated with absorption and compliance issues which have prompted us to investigate skin as an alternative site of administration. Delivery through skin, however, is restricted to small and moderately lipophilic molecules due to the outermost barrier, the stratum corneum (SC). In this study, we have investigated the effect of different enhancement techniques, chemical enhancers (ethanol, oleic acid, propylene glycol), iontophoresis (anodal iontophoresis) and microneedles (soluble maltose microneedles), which may overcome this barrier and improve cyanocobalamin delivery. Studies with different chemical enhancer formulations indicated that ethanol and oleic acid decreased the lag time while propylene glycol based formulations increased the lag time. The formulation with ethanol (50%), oleic acid (10%) and propylene glycol (40%) showed the maximum improvement in delivery. Iontophoresis and microneedle treatments resulted in enhanced permeation levels compared to passive controls. These enhancement approaches can be explored further to develop alternative treatment regimens. http://www.mdpi.com/1999-4923/3/3/474 Wed, 10 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-10 3 3 Article 474 484 1999-4923 Effects of Chemical and Physical Enhancement Techniques on Transdermal Delivery of Cyanocobalamin (Vitamin B12) In Vitro 2011-08-10 doi: 10.3390/pharmaceutics3030474 Ye Yang Haripriya Kalluri Ajay K. Banga http://www.mdpi.com/1999-4923/3/3/458 Research concerning new targeting delivery systems for pharmacologically active molecules and genetic material is of great importance. The aim of the present study was to investigate the potential of fourth generation (P4) cationic phosphorus-containing dendrimers to bind fluorescent probe 8-anilino-1-naphthalenesulfonate (ANS), anti-neoplastic drug cisplatin, anti-HIV siRNA siP24 and its capability to deliver green fluorescent protein gene (pGFP) into cells. The interaction between P4 and ANS (as the model drug) was investigated. The binding constant and the number of binding centers per one molecule of P4 were determined. In addition, the dendriplex between P4 and anti-HIV siRNA siP24 was characterized using circular dichroism, fluorescence polarization and zeta-potential methods; the average hydrodynamic diameter of the dendriplex was calculated using zeta-size measurements. The efficiency of transfection of pGFP using P4 was determined in HEK293 cells and human mesenchymal stem cells, and the cytotoxicity of the P4-pGFP dendriplex was studied. Furthermore, enhancement of the toxic action of the anti-neoplastic drug cisplatin by P4 dendrimers was estimated. Based on the results, the fourth generation cationic phosphorus-containing dendrimers seem to be a good drug and gene delivery carrier candidate. http://www.mdpi.com/1999-4923/3/3/458 Fri, 05 Aug 2011 00:00:00 CEST Pharmaceutics 2011-08-05 3 3 Article 458 473 1999-4923 Fourth Generation Phosphorus-Containing Dendrimers: Prospective Drug and Gene Delivery Carrier 2011-08-05 doi: 10.3390/pharmaceutics3030458 D. Shcharbin V. Dzmitruk A. Shakhbazau N. Goncharova I. Seviaryn S. Kosmacheva M. Potapnev E. Pedziwiatr-Werbicka M. Bryszewska M. Talabaev A. Chernov V. Kulchitsky A.-M. Caminade J.-P. Majoral http://www.mdpi.com/1999-4923/3/3/440 Gelatin is a principal excipient used as a binder in the formulation of lyophilized orally disintegrating tablets. The current study focuses on exploiting the physicochemical properties of gelatin by varying formulation parameters to determine their influence on orally disintegrating tablet (ODT) characteristics. Process parameters, namely pH and ionic strength of the formulations, and ball milling were investigated to observe their effects on excipient characteristics and tablet formation. The properties and characteristics of the formulations and tablets which were investigated included: glass transition temperature, wettability, porosity, mechanical properties, disintegration time, morphology of the internal structure of the freeze-dried tablets, and drug dissolution. The results from the pH study revealed that adjusting the pH of the formulation away from the isoelectric point of gelatin, resulted in an improvement in tablet disintegration time possibly due to increase in gelatin swelling resulting in greater tablet porosity. The results from the ionic strength study revealed that the inclusion of sodium chloride influenced tablet porosity, tablet morphology and the glass transition temperature of the formulations. Data from the milling study showed that milling the excipients influenced formulation characteristics, namely wettability and powder porosity. The study concludes that alterations of simple parameters such as pH and salt concentration have a significant influence on formulation of ODT. http://www.mdpi.com/1999-4923/3/3/440 Wed, 20 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-20 3 3 Article 440 457 1999-4923 The Influence of Formulation and Manufacturing Process Parameters on the Characteristics of Lyophilized Orally Disintegrating Tablets 2011-07-20 doi: 10.3390/pharmaceutics3030440 Rhys J. Jones Ali Rajabi-Siahboomi Marina Levina Yvonne Perrie Afzal R. Mohammed http://www.mdpi.com/1999-4923/3/3/425 The number of drug-related emergency room visits in the United States doubled from 2004 to 2009 to 4.6 million. Consequently there is a critical need to rapidly identify the offending drug(s), so that the appropriate medical care can be administered. In an effort to meet this need we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect and identify numerous drugs in saliva at ng/mL concentrations within 10 minutes. Identification is provided by matching measured spectra to a SERS library comprised of over 150 different drugs, each of which possess a unique spectrum. Trace detection is provided by fused gold colloids trapped within a porous glass matrix that generate SERS. Speed is provided by a syringe-driven sample system that uses a solid-phase extraction capillary combined with a SERS-active capillary in series. Spectral collection is provided by a portable Raman analyzer. Here we describe successful measurement of representative illicit, prescribed, and over-the-counter drugs by SERS, and 50 ng/mL cocaine in saliva as part of a focused study. http://www.mdpi.com/1999-4923/3/3/425 Wed, 13 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-13 3 3 Article 425 439 1999-4923 Rapid Detection and Identification of Overdose Drugs in Saliva by Surface-Enhanced Raman Scattering Using Fused Gold Colloids 2011-07-13 doi: 10.3390/pharmaceutics3030425 Stuart Farquharson Chetan Shende Atanu Sengupta Hermes Huang Frank Inscore http://www.mdpi.com/1999-4923/3/3/406 Four guanidine derivatives of N4,N9-diacylated spermine have been designed, synthesized, and characterized. These guanidine-containing cationic lipids bound siRNA and formed nanoparticles. Two cationic lipids with C18 unsaturated chains, N1,N12-diamidino-N4,N9-dioleoylspermine and N1,N12-diamidino-N4-linoleoyl-N9-oleoylspermine, were more efficient in terms of GFP expression reduction compared to the other cationic lipids with shorter C12 (12:0) and very long C22 (22:1) chains. N1,N12-Diamidino-N4-linoleoyl-N9-oleoylspermine siRNA lipoplexes resulted in GFP reduction (26%) in the presence of serum, and cell viability (64%). These data are comparable to those obtained with TransIT TKO. Thus, cationic lipid guanidines based on N4,N9-diacylated spermines are good candidates for non-viral delivery of siRNA to HeLa cells using self-assembled lipoplexes. http://www.mdpi.com/1999-4923/3/3/406 Wed, 13 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-13 3 3 Article 406 424 1999-4923 Self-Assembled Lipoplexes of Short Interfering RNA (siRNA) Using Spermine-Based Fatty Acid Amide Guanidines: Effect on Gene Silencing Efficiency 2011-07-13 doi: 10.3390/pharmaceutics3030406 Abdelkader A. Metwally Ian S. Blagbrough http://www.mdpi.com/1999-4923/3/3/379 Incorporation of a pH-sensitive conformational switch into a lipid structure enables a drastic conformational flip upon protonation that disrupts the liposome membrane and causes rapid release of cargo specifically in areas of increased acidity. pH-sensitive liposomes containing the amphiphile (1) with trans-2-morpholinocyclohexanol conformational switch, a phospholipid, and a PEG-lipid conjugate were constructed and characterized. The optimized composition—1/POPC/PEG-ceramide (50/45/5)—could be stored at 4 °C and pH 7.4 for up to 1.5 years, and was stable in blood serum in vitro after 48 h at 37 °C. Liposomes loaded with ANTS/DPX or methotrexate demonstrated an unusually quick content release (in a few seconds) at pH below 5.5, which was independent of inter-liposome contact. The pH-titration curve for the liposome leakage paralleled the curve for the acid-induced conformational flip of 1 studied by 1H-NMR. Freeze-fracture electron microscopy images showed budding and division of the bilayer at pH 5.5. A plausible mechanism of pH-sensitivity involves an acid-triggered conformational flip of 1, shortening of lipid tails, and membrane perturbations, which cause the content leakage. The methotrexate-loaded liposomes demonstrated much higher cytotoxicity in HeLa cells than the free drug indicating that they can serve as viable drug delivery systems. http://www.mdpi.com/1999-4923/3/3/379 Mon, 11 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-11 3 3 Article 379 405 1999-4923 Fliposomes: pH-Sensitive Liposomes Containing a trans-2-morpholinocyclohexanol-Based Lipid That Performs a Conformational Flip and Triggers an Instant Cargo Release in Acidic Medium 2011-07-11 doi: 10.3390/pharmaceutics3030379 Nataliya M. Samoshina Xin Liu Barbora Brazdova Andreas H. Franz Vyacheslav V. Samoshin Xin Guo http://www.mdpi.com/1999-4923/3/3/354 Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2–3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness. http://www.mdpi.com/1999-4923/3/3/354 Mon, 11 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-11 3 3 Review 354 378 1999-4923 Advances in Bio-Optical Imaging for the Diagnosis of Early Oral Cancer 2011-07-11 doi: 10.3390/pharmaceutics3030354 Malini Olivo Ramaswamy Bhuvaneswari Ivan Keogh http://www.mdpi.com/1999-4923/3/3/338 The major limitation of the clinical use of replication-incompetent adenovirus (Ad) vectors is the interference by innate immune responses, including induction of inflammatory cytokines and interferons (IFN), following in vivo application of Ad vectors. Ad vector-induced production of inflammatory cytokines and IFNs also results in severe organ damage and efficient induction of acquired immune responses against Ad proteins and transgene products. Ad vector-induced innate immune responses are triggered by the recognition of Ad components by pattern recognition receptors (PRRs). In order to reduce the side effects by Ad vector-induced innate immune responses and to develop safer Ad vectors, it is crucial to clarify which PRRs and which Ad components are involved in Ad vector-induced innate immune responses. Our group previously demonstrated that myeloid differentiating factor 88 (MyD88) and toll-like receptor 9 (TLR9) play crucial roles in the Ad vector-induced inflammatory cytokine production in mouse bone marrow-derived dendritic cells. Furthermore, our group recently found that virus associated-RNAs (VA-RNAs), which are about 160 nucleotide-long non-coding small RNAs encoded in the Ad genome, are involved in IFN production through the IFN-β promoter stimulator-1 (IPS-1)-mediated signaling pathway following Ad vector transduction. The aim of this review is to highlight the Ad vector-induced innate immune responses following transduction, especially VA-RNA-mediated innate immune responses. Our findings on the mechanism of Ad vector-induced innate immune responses should make an important contribution to the development of safer Ad vectors, such as an Ad vector lacking expression of VA-RNAs. http://www.mdpi.com/1999-4923/3/3/338 Mon, 11 Jul 2011 00:00:00 CEST Pharmaceutics 2011-07-11 3 3 Review 338 353 1999-4923 Adenovirus Vector-Derived VA-RNA-Mediated Innate Immune Responses 2011-07-11 doi: 10.3390/pharmaceutics3030338 Mitsuhiro Machitani Tomoko Yamaguchi Kahori Shimizu Fuminori Sakurai Kazufumi Katayama Kenji Kawabata Hiroyuki Mizuguchi http://www.mdpi.com/1999-4923/3/2/326 Certain triple nucleoside/tide reverse transcriptase inhibitor (NRTI) regimens containing tenofovir (TDF) have been associated with rapid early treatment failure. The mechanism is unknown, but may be at the level of drug transport. We measured the lipophilicity of the drugs [3H]-lamivudine (3TC), -didanosine (ddI), -TDF and -ABC. Peripheral blood mononuclear cells (PBMCs) were used to evaluate drug–drug interactions at the level of drug transport. PBMCs were measured for the expression of P-glycoprotein (P-gp), multidrug resistance-associated protein-1 (MRP-1) and breast cancer resistance protein (BCRP) by flow cytometry. The rank order of the lipophilicity of the drugs were ABC>>>3TC³ddI>TDF. The accumulation of [3H]-3TC, -ddI and -TDF were temperature sensitive (suggesting facilitated transport), in contrast to [3H]-ABC. ABC reduced the accumulation of [3H]-3TC, and cell fractionation experiments suggested this was mainly in membrane-bound [3H]-3TC. ABC/TDF and ABC/ddI increased the accumulation of [3H]-3TC and 3TC/TDF also increased the accumulation of [3H]-TDF. In contrast, none of the NRTI/NtRTI incubations (alone or in combination) altered the accumulation of [3H]-ABC and -ddI. PBMC expression of P-gp, MRP1 and BCRP were detected, but none correlated with the accumulation of the drugs. The high failure rates seen with TDF, ABC and 3TC are not fully explained by an interaction at transporter level. http://www.mdpi.com/1999-4923/3/2/326 Wed, 22 Jun 2011 00:00:00 CEST Pharmaceutics 2011-06-22 3 2 Article 326 337 1999-4923 Interactions of Tenofovir, Lamivudine, Abacavir and Didanosine in Primary Human Cells 2011-06-22 doi: 10.3390/pharmaceutics3020326 Omar Janneh Saye H. Khoo http://www.mdpi.com/1999-4923/3/2/315 Porous silicon (PSi) is an innovative inorganic material that has been recently developed for various drug delivery systems. For example, hydrophilic and hydrophobic PSi microparticles have been utilized to improve the dissolution rate of poorly soluble drugs and to sustain peptide delivery. Previously, the well-plate method has been demonstrated to be a suitable in vitro dissolution method for hydrophilic PSi particles but it was not applicable to poorly wetting hydrophobic thermally hydrocarbonized PSi (THCPSi) particles. In this work, three different in vitro dissolution techniques, namely centrifuge, USP Apparatus 1 (basket) and well-plate methods were compared by using hydrophilic thermally carbonized PSi (TCPSi) microparticles loaded with poorly soluble ibuprofen or freely soluble antipyrine. All the methods showed a fast and complete or nearly complete release of both model compounds from the TCPSi microparticles indicating that all methods described in vitro dissolution equally. Based on these results, the centrifuge method was chosen to study the release of a peptide (ghrelin antagonist) from the THCPSi microparticles since it requires small sample amounts and achieves good particle suspendability. Sustained peptide release from the THCPSi microparticles was observed, which is in agreement with an earlier in vivo study. In conclusion, the centrifuge method was demonstrated to be a suitable tool for the evaluation of drug release from hydrophobic THCPSi particles, and the sustained peptide release from THCPSi microparticles was detected. http://www.mdpi.com/1999-4923/3/2/315 Tue, 21 Jun 2011 00:00:00 CEST Pharmaceutics 2011-06-21 3 2 Article 315 325 1999-4923 In Vitro Dissolution Methods for Hydrophilic and Hydrophobic Porous Silicon Microparticles 2011-06-21 doi: 10.3390/pharmaceutics3020315 Juha Mönkäre Joakim Riikonen Elina Rauma Jarno Salonen Vesa-Pekka Lehto Kristiina Järvinen http://www.mdpi.com/1999-4923/3/2/307 Recently, it has been demonstrated that particulate substances penetrate preferentially into the hair follicles and that the penetration depth depends on the particle size. In the present study, the influence of the vehicle of the particulate substances on the penetration depth was investigated. Four different formulations (ethanolic suspension, aqueous suspension, ethanolic gel and aqueous gel) containing peptide-loaded particles of 1 µm in diameter were prepared and applied on porcine ear skin. After penetration, punch biopsies were taken and the penetration depths of the particles were investigated by laser scanning microscopy. The deepest penetration was achieved with the gel formulations demonstrating an influence of the vehicle on the penetration depth of particulate substances. http://www.mdpi.com/1999-4923/3/2/307 Tue, 14 Jun 2011 00:00:00 CEST Pharmaceutics 2011-06-14 3 2 Article 307 314 1999-4923 Influence of the Vehicle on the Penetration of Particles into Hair Follicles 2011-06-14 doi: 10.3390/pharmaceutics3020307 Alexa Patzelt Heike Richter Lars Dähne Peter Walden Karl-Heinz Wiesmüller Ute Wank Wolfram Sterry Jürgen Lademann http://www.mdpi.com/1999-4923/3/2/275 Mild non-ionic sucrose ester surfactants can be employed to produce lipid-based drug delivery systems for dermal application. Moreover, sucrose esters of intermediate lipophilicity such as sucrose stearate S-970 possess a peculiar rheological behavior which can be employed to create highly viscous semi-solid formulations without any further additives. Interestingly, it was possible to develop both viscous macroemulsions and fluid nanoemulsions with the same chemical composition merely by slight alteration of the production process. Optical light microscopy and cryo transmission electron microscopy (TEM) revealed that the sucrose ester led to the formation of an astonishing hydrophilic network at a concentration of only 5% w/w in the macroemulsion system. A small number of more finely structured aggregates composed of surplus surfactant were likewise detected in the nanoemulsions. These discoveries offer interesting possibilities to adapt the low viscosity of fluid O/W nanoemulsions for a more convenient application. Moreover, a simple and rapid production method for skin-friendly creamy O/W emulsions with excellent visual long-term stability is presented. It could be shown by franz-cell diffusion studies and in vitro tape stripping that the microviscosity within the semi-solid formulations was apparently not influenced by their increased macroviscosity: the release of three model drugs was not impaired by the complex network-like internal structure of the macroemulsions. These results indicate that the developed semi-solid emulsions with advantageous application properties are highly suitable for the unhindered delivery of lipophilic drugs despite their comparatively large particle size and high viscosity. http://www.mdpi.com/1999-4923/3/2/275 Mon, 30 May 2011 00:00:00 CEST Pharmaceutics 2011-05-30 3 2 Article 275 306 1999-4923 Semi-solid Sucrose Stearate-Based Emulsions as Dermal Drug Delivery Systems 2011-05-30 doi: 10.3390/pharmaceutics3020275 Victoria Klang Julia C. Schwarz Nadejda Matsko Elham Rezvani Nivine El-Hagin Michael Wirth Claudia Valenta http://www.mdpi.com/1999-4923/3/2/229 Fluorescence microscopic imaging is widely used in biomedical research to study molecular and cellular processes in cell culture or tissue samples. This is motivated by the high inherent sensitivity of fluorescence techniques, the spatial resolution that compares favorably with cellular dimensions, the stability of the fluorescent labels used and the sophisticated labeling strategies that have been developed for selectively labeling target molecules. More recently, two and three-dimensional optical imaging methods have also been applied to monitor biological processes in intact biological organisms such as animals or even humans. These whole body optical imaging approaches have to cope with the fact that biological tissue is a highly scattering and absorbing medium. As a consequence, light propagation in tissue is well described by a diffusion approximation and accurate reconstruction of spatial information is demanding. While in vivo optical imaging is a highly sensitive method, the signal is strongly surface weighted, i.e., the signal detected from the same light source will become weaker the deeper it is embedded in tissue, and strongly depends on the optical properties of the surrounding tissue. Derivation of quantitative information, therefore, requires tomographic techniques such as fluorescence molecular tomography (FMT), which maps the three-dimensional distribution of a fluorescent probe or protein concentration. The combination of FMT with a structural imaging method such as X-ray computed tomography (CT) or Magnetic Resonance Imaging (MRI) will allow mapping molecular information on a high definition anatomical reference and enable the use of prior information on tissue’s optical properties to enhance both resolution and sensitivity. Today many of the fluorescent assays originally developed for studies in cellular systems have been successfully translated for experimental studies in animals. The opportunity of monitoring molecular processes non-invasively in the intact organism is highly attractive from a diagnostic point of view but even more so for the drug developer, who can use the techniques for proof-of-mechanism and proof-of-efficacy studies. This review shall elucidate the current status and potential of fluorescence tomography including recent advances in multimodality imaging approaches for preclinical and clinical drug development. http://www.mdpi.com/1999-4923/3/2/229 Tue, 26 Apr 2011 00:00:00 CEST Pharmaceutics 2011-04-26 3 2 Review 229 274 1999-4923 Fluorescence Molecular Tomography: Principles and Potential for Pharmaceutical Research 2011-04-26 doi: 10.3390/pharmaceutics3020229 Florian Stuker Jorge Ripoll Markus Rudin http://www.mdpi.com/1999-4923/3/2/186 Protein kinase D (PKD) belongs to a family of serine/threonine kinases that play an important role in basic cellular processes and are implicated in the pathogenesis of several diseases. Progress in our understanding of the biological functions of PKD has been limited due to the lack of a PKD-specific inhibitor. The benzoxoloazepinolone CID755673 was recently reported as the first potent and kinase-selective inhibitor for this enzyme. For structure-activity analysis purposes, a series of analogs was prepared and their in vitro inhibitory potency evaluated. http://www.mdpi.com/1999-4923/3/2/186 Thu, 21 Apr 2011 00:00:00 CEST Pharmaceutics 2011-04-21 3 2 Article 186 228 1999-4923 Design, Synthesis, and Biological Evaluation of PKD Inhibitors 2011-04-21 doi: 10.3390/pharmaceutics3020186 Kara M. George Marie-Céline Frantz Karla Bravo-Altamirano Courtney R. LaValle Manuj Tandon Stephanie Leimgruber Elizabeth R. Sharlow John S. Lazo Q. Jane Wang Peter Wipf http://www.mdpi.com/1999-4923/3/2/171 The field of nanotechnology has exploded in recent years with diverse arrays of applications. Cancer therapeutics have recently seen benefit from nanotechnology with the approval of some early nanoscale drug delivery systems. A diversity of novel delivery systems are currently under investigation and an array of newly developed, customized particles have reached clinical application. Drug delivery systems have traditionally relied on passive targeting via increased vascular permeability of malignant tissue, known as the enhanced permeability and retention effect (EPR). More recently, there has been an increased use of active targeting by incorporating cell specific ligands such as monoclonal antibodies, lectins, and growth factor receptors. This customizable approach has raised the possibility of drug delivery systems capable of multiple, simultaneous functions, including applications in diagnostics, imaging, and therapy which is paving the way to improved early detection methods, more effective therapy, and better survivorship for cancer patients. http://www.mdpi.com/1999-4923/3/2/171 Thu, 14 Apr 2011 00:00:00 CEST Pharmaceutics 2011-04-14 3 2 Review 171 185 1999-4923 Nanotechnology and Drug Delivery: An Update in Oncology 2011-04-14 doi: 10.3390/pharmaceutics3020171 Tait Jones Nabil Saba http://www.mdpi.com/1999-4923/3/2/141 Dynamic regulation of specific molecular processes and cellular phenotypes in live cell systems reveal unique insights into cell fate and drug pharmacology that are not gained from traditional fixed endpoint assays. Recent advances in microscopic imaging platform technology combined with the development of novel optical biosensors and sophisticated image analysis solutions have increased the scope of live cell imaging applications in drug discovery. We highlight recent literature examples where live cell imaging has uncovered novel insight into biological mechanism or drug mode-of-action. We survey distinct types of optical biosensors and associated analytical methods for monitoring molecular dynamics, in vitro and in vivo. We describe the recent expansion of live cell imaging into automated target validation and drug screening activities through the development of dedicated brightfield and fluorescence kinetic imaging platforms. We provide specific examples of how temporal profiling of phenotypic response signatures using such kinetic imaging platforms can increase the value of in vitro high-content screening. Finally, we offer a prospective view of how further application and development of live cell imaging technology and reagents can accelerate preclinical lead optimization cycles and enhance the in vitro to in vivo translation of drug candidates. http://www.mdpi.com/1999-4923/3/2/141 Mon, 04 Apr 2011 00:00:00 CEST Pharmaceutics 2011-04-04 3 2 Review 141 170 1999-4923 Live Cell in Vitro and in Vivo Imaging Applications: Accelerating Drug Discovery 2011-04-04 doi: 10.3390/pharmaceutics3020141 Beverley Isherwood Paul Timpson Ewan J McGhee Kurt I Anderson Marta Canel Alan Serrels Valerie G Brunton Neil O Carragher http://www.mdpi.com/1999-4923/3/2/125 Gene silencing by siRNA (synthetic dsRNA of 21-25 nucleotides) is a well established biological tool in gene expression studies and has a promising therapeutic potential for difficult-to-treat diseases. Five fatty acids of various chain length and oxidation state (C12:0, C18:0, C18:1, C18:2, C22:1) were conjugated to the naturally occurring polyamine, spermine, and evaluated for siRNA delivery and gene knock-down. siRNA delivery could not be related directly to gene silencing efficiency as N4,N9-dierucoyl spermine resulted in higher siRNA delivery compared to N4,N9-dioleoyl spermine. GFP silencing in HeLa cells showed that the unsaturated fatty acid amides are more efficient than saturated fatty acid amides, with N4,N9-dioleoyl spermine resulting in the most efficient gene silencing in the presence of serum. The alamarBlue cell viability assay showed that fatty acid amides of spermine have good viability (75%–85% compared to control) except N4,N9-dilauroyl spermine which resulted in low cell viability. These results prove that unsaturated fatty acid amides of spermine are efficient, non-toxic, non-viral vectors for siRNA mediated gene silencing. http://www.mdpi.com/1999-4923/3/2/125 Fri, 25 Mar 2011 00:00:00 CET Pharmaceutics 2011-03-25 3 2 Article 125 140 1999-4923 Efficient Gene Silencing by Self-Assembled Complexes of siRNA and Symmetrical Fatty Acid Amides of Spermine 2011-03-25 doi: 10.3390/pharmaceutics3020125 Abdelkader A. Metwally Charareh Pourzand Ian S. Blagbrough http://www.mdpi.com/1999-4923/3/1/107 Cell migration and invasion are processes that offer rich targets for intervention in key physiologic and pathologic phenomena such as wound healing and cancer metastasis. With the advent of high-throughput and high content imaging systems, there has been a movement towards the use of physiologically relevant cell-based assays earlier in the testing paradigm. This allows more effective identification of lead compounds and recognition of undesirable effects sooner in the drug discovery screening process. This article will review the effective use of several principle formats for studying cell motility: scratch assays, transmembrane assays, microfluidic devices and cell exclusion zone assays. http://www.mdpi.com/1999-4923/3/1/107 Fri, 11 Mar 2011 00:00:00 CET Pharmaceutics 2011-03-11 3 1 Review 107 124 1999-4923 Cell Migration and Invasion Assays as Tools for Drug Discovery 2011-03-11 doi: 10.3390/pharmaceutics3010107 Keren I. Hulkower Renee L. Herber http://www.mdpi.com/1999-4923/3/1/88 PET (Positron Emission Tomography) allows imaging of the in vivo distribution of biochemical compounds labeled with a radioactive tracer, mainly 18F-FDG (2-deoxy-2-[18F] fluoro-D-glucose). 18F only allows a relatively poor spatial resolution (2-3 mm) which does not allow imaging of small tumors or specific small size tissues, e.g. vasculature. Unfortunately, angiogenesis is a key process in various physiologic and pathologic processes and is, for instance, involved in modern anticancer approaches. Thus ability to visualize angiogenesis could allow early diagnosis and help to monitor the response of cancer to specific chemotherapies. Therefore, indirect analytical techniques are required to assess the localization of fluorinated compounds at a micrometric scale. Multimodality imaging approaches could provide accurate information on the metabolic activity of the target tissue. In this article, PIGE method (Particle Induced Gamma-ray Emission) was used to determine fluorinated tracers by the nuclear reaction of 19F(p,p′γ)19F in tissues. The feasibility of this approach was assessed on polyfluorinated model glucose compounds and novel peptide-based tracer designed for angiogenesis imaging. Our results describe the first mapping of the biodistribution of fluorinated compounds in both vascularized normal tissue and tumor tissue. http://www.mdpi.com/1999-4923/3/1/88 Wed, 09 Mar 2011 00:00:00 CET Pharmaceutics 2011-03-09 3 1 Article 88 106 1999-4923 First Quantitative Imaging of Organic Fluorine within Angiogenic Tissues by Particle Induced Gamma-Ray Emission (PIGE) Analysis: First PIGE Organic Fluorine Imaging 2011-03-09 doi: 10.3390/pharmaceutics3010088 Sébastien Lavielle Karine Gionnet Richard Ortega Guillaume Devès Victor Kilarski Katia Wehbe Andreas Bikfalvi Gérard Déléris http://www.mdpi.com/1999-4923/3/1/73 A novel abuse deterrent, prolonged release tablet formulation of Hydrocodone for once-daily dosing has been developed, based on the novel proprietary Egalet® ADPREM technology. The tablet is an injection molded polymer system consisting of an erodible matrix in which the Active Pharmaceutical Ingredient (API), such as Hydrocodone, is dispersed. The matrix is partly covered with a water-impermeable, non-erodible shell which leaves both ends of the cylindrical tablet exposed to erosion by the gastrointestinal (GI) fluid. In vivo–in vitro correlation (IVIVC) was initiated and validated with three formulations. A good internal predictability was observed for the three formulations. How the changing conditions in the GI tract influenced in vivo performance of an erosion based product was discussed. The validated IVIVC could be used to optimize the tablet formulation and to obtain a desired profile. In addition, this technique could help to establish the dissolution limits in which a certainty of bioequivalence is calculated. Based on this validated level A IVIVC, dissolution can be used as surrogate of bioequivalence for development, but also scale up post approval changes. http://www.mdpi.com/1999-4923/3/1/73 Wed, 09 Mar 2011 00:00:00 CET Pharmaceutics 2011-03-09 3 1 Article 73 87 1999-4923 Development of a New Type of Prolonged Release Hydrocodone Formulation Based on Egalet® ADPREM Technology Using In Vivo–In Vitro Correlation 2011-03-09 doi: 10.3390/pharmaceutics3010073 Pernille H. Hemmingsen Anne-Mette Haahr Christine Gunnergaard Jean-Michel Cardot http://www.mdpi.com/1999-4923/3/1/53 Many physiologic differences between children and adults may result in age-related changes in pharmacokinetics and pharmacodynamics. Factors such as gastric pH and emptying time, intestinal transit time, immaturity of secretion and activity of bile and pancreatic fluid among other factors determine the oral bioavailability of pediatric and adult populations. Anatomical, physiological and biochemical characteristics in children also affect the bioavailability of other routes of administration. Key factors explaining differences in drug distribution between the pediatric population and adults are membrane permeability, plasma protein binding and total body water. As far as drug metabolism is concerned, important differences have been found in the pediatric population compared with adults both for phase I and phase II metabolic enzymes. Immaturity of glomerular filtration, renal tubular secretion and tubular reabsorption at birth and their maturation determine the different excretion of drugs in the pediatric population compared to adults. http://www.mdpi.com/1999-4923/3/1/53 Mon, 07 Feb 2011 00:00:00 CET Pharmaceutics 2011-02-07 3 1 Review 53 72 1999-4923 Factors and Mechanisms for Pharmacokinetic Differences between Pediatric Population and Adults 2011-02-07 doi: 10.3390/pharmaceutics3010053 Eva Fernandez Raul Perez Alfredo Hernandez Pilar Tejada Marta Arteta Jose T. Ramos http://www.mdpi.com/1999-4923/3/1/34 Current first-line treatments for most cancers feature a short-list of highly potent and often target-blind interventions, including chemotherapy, radiation, and surgical excision. These treatments wreak considerable havoc upon non-cancerous tissue and organs, resulting in deleterious and sometimes fatal side effects for the patient. In response, this past decade has witnessed the robust emergence of nanoparticles and, more relevantly, nanoparticle drug delivery systems (DDS), widely touted as the panacea of cancer therapeutics. While not a cure, nanoparticle DDS can successfully negotiate the clinical payoff between drug dosage and side effects by encompassing target-specific drug delivery strategies. The expanding library of nanoparticles includes lipoproteins, liposomes, dendrimers, polymers, metal and metal oxide nano-spheres and -rods, and carbon nanotubes, so do the modes of delivery. Importantly, however, the pharmaco-dynamics and –kinetics of these nano-complexes remain an urgent issue and a serious bottleneck in the transition from bench to bedside. This review addresses the rise of nanoparticle DDS platforms for cancer and explores concepts of gene/drug delivery and cytotoxicity in pre-clinical and clinical contexts. http://www.mdpi.com/1999-4923/3/1/34 Thu, 13 Jan 2011 00:00:00 CET Pharmaceutics 2011-01-13 3 1 Review 34 52 1999-4923 Nano Delivers Big: Designing Molecular Missiles for Cancer Therapeutics 2011-01-13 doi: 10.3390/pharmaceutics3010034 Sachin Patel Ashwin A. Bhirde James F. Rusling Xiaoyuan Chen J. Silvio Gutkind Vyomesh Patel http://www.mdpi.com/1999-4923/3/1/12 Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under the curve (AUC) are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III)-hydroxide complexes with carbohydrate ligands or orally as iron(II) (ferrous) salts or iron(III) (ferric) complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia. http://www.mdpi.com/1999-4923/3/1/12 Tue, 04 Jan 2011 00:00:00 CET Pharmaceutics 2011-01-04 3 1 Review 12 33 1999-4923 The Pharmacokinetics and Pharmacodynamics of Iron Preparations 2011-01-04 doi: 10.3390/pharmaceutics3010012 Peter Geisser Susanna Burckhardt http://www.mdpi.com/1999-4923/3/1/1 We have reported that PEGylated liposomes lose their long-circulating properties when they are administered repeatedly at certain intervals to the same animal. This unexpected phenomenon is referred to as the accelerated blood clearance (ABC) phenomenon. We recently showed that the ABC phenomenon is triggered via the abundant secretion of anti-PEG IgM in response to the first dose of PEGylated liposomes. However, the details of the underlying mechanism for the induction of anti-PEG IgM production are yet to be elucidated. The present study demonstrated that the spleen is a major organ involved in the secretion of anti-PEG IgM in mice and rats. Anti-PEG IgM production was detected in nude, T-cell deficient mice, but not in SCID mice with B- and T-cell deficiencies. These observations indicate that splenic B-cells secret anti-PEG IgM without help from T-cells. Sequential injections of PEGylated liposomes into the same mice did not promote isotype switching from IgM to IgG. Accordingly, PEGylated liposomes may function as a type-2, T-cell-independent antigen (TI-2 antigen) during anti-PEG IgM production. Although the underlying mechanism that causes an anti-PEG IgM response against PEGylated liposomes is not yet clear, our findings give implications in revealing the anti-PEG IgM response against PEGylated liposome. http://www.mdpi.com/1999-4923/3/1/1 Mon, 27 Dec 2010 00:00:00 CET Pharmaceutics 2010-12-27 3 1 Article 1 11 1999-4923 Anti-PEG IgM Response against PEGylated Liposomes in Mice and Rats 2010-12-27 doi: 10.3390/pharmaceutics3010001 Masako Ichihara Taro Shimizu Ami Imoto Yuki Hashiguchi Yumi Uehara Tatsuhiro Ishida Hiroshi Kiwada http://www.mdpi.com/1999-4923/2/4/419 Particle size reduction is a simple means to enhance the dissolution rate of poorly water soluble BCS-class II and IV drugs. However, the major drawback of this process is the possible introduction of process induced disorder. Drugs with different molecular arrangements may exhibit altered properties such as solubility and dissolution rate and, therefore, process induced solid state modifications need to be monitored. The aim of this study was two-fold: firstly, to investigate the dissolution rates of milled and unmilled simvastatin; and secondly, to screen for the main milling factors, as well as factor interactions in a dry ball milling process using simvastatin as model drug, and to optimize the milling procedure with regard to the opposing responses particle size and process induced disorder by application of a central composite face centered design. Particle size was assessed by scanning electron microscopy (SEM) and image analysis. Process induced disorder was determined by partial least squares (PLS) regression modeling of respective X-ray powder diffractograms (XRPD) and Raman spectra. Valid and significant quadratic models were built. The investigated milling factors were milling frequency, milling time and ball quantity at a set drug load, out of which milling frequency was found to be the most important factor for particle size as well as process induced disorder. Milling frequency and milling time exhibited an interaction effect on the responses. The optimum milling settings using the maximum number of milling balls (60 balls with 4 mm diameter) was determined to be at a milling frequency of 21 Hz and a milling time of 36 min with a resulting primary particle size of 1.4 μm and a process induced disorder of 6.1% (assessed by Raman spectroscopy) and 8.4% (assessed by XRPD), at a set optimization limit of < 2 μm for particle size and < 10% for process induced disorder. This optimum was tested experimentally and the process induced disorder was determined to be 6.9% (± 2.2) by Raman spectroscopy and 7.8% (± 2.3) by XRPD. Subsequent intrinsic dissolution testing revealed that the process induced disorder was negligible with regard to the dissolution rate. The predicted primary particle size of 1.4 μm could be confirmed experimentally, but due to agglomeration of the primary particles a dissolution rate advantage was not shown, highlighting the importance of dissolution testing at an early stage of drug development. http://www.mdpi.com/1999-4923/2/4/419 Fri, 17 Dec 2010 00:00:00 CET Pharmaceutics 2010-12-17 2 4 Article 419 431 1999-4923 The Influence of Milling on the Dissolution Performance of Simvastatin 2010-12-17 doi: 10.3390/pharmaceutics2040419 Ulrike Zimper Jaakko Aaltonen Karen Krauel-Goellner Keith C. Gordon Clare J. Strachan Thomas Rades http://www.mdpi.com/1999-4923/2/4/389 Although pediatric doses for biotherapeutics are often based on patients' body weight (mg/kg) or body surface area (mg/m2), linear body size dose adjustment is highly empirical. Growth and maturity are also important factors that affect the absorption, distribution, metabolism and excretion (ADME) of biologics in pediatrics. The complexity of the factors involved in pediatric pharmacokinetics lends to the reconsideration of body size based dose adjustment. A proper dosing adjustment for pediatrics should also provide less intersubject variability in the pharmacokinetics and/or pharmacodynamics of the product compared with no dose adjustment. Biological proteins and peptides generally share the same pharmacokinetic principle with small molecules, but the underlying mechanism can be very different. Here, pediatric and adult pharmacokinetic parameters are compared and summarized for selected biotherapeutics. The effect of body size on the pediatric pharmacokinetics for these biological products is discussed in the current review. http://www.mdpi.com/1999-4923/2/4/389 Thu, 16 Dec 2010 00:00:00 CET Pharmaceutics 2010-12-16 2 4 Review 389 418 1999-4923 Pediatric Dosing and Body Size in Biotherapeutics 2010-12-16 doi: 10.3390/pharmaceutics2040389 Rong Shi Hartmut Derendorf http://www.mdpi.com/1999-4923/2/4/364 Pediatric aspects are nowadays integrated early in the development process of a new drug. The stronger enforcement to obtain pediatric information by the regulatory agencies in recent years resulted in an increased number of trials in children. Specific guidelines and requirements from, in particular, the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) form the regulatory framework. This review summarizes the regulatory requirements and strategies for pediatric drug development from an industry perspective. It covers pediatric study planning and conduct, considerations for first dose in children, appropriate sampling strategies, and different methods for data generation and analysis to generate knowledge about the pharmacokinetics (PK) and pharmacodynamics (PD) of a drug in children. The role of Modeling and Simulation (M&S) in pediatrics is highlighted—including the regulatory basis—and examples of the use of M&S are illustrated to support pediatric drug development. http://www.mdpi.com/1999-4923/2/4/364 Mon, 29 Nov 2010 00:00:00 CET Pharmaceutics 2010-11-29 2 4 Review 364 388 1999-4923 Drug Development for Pediatric Populations: Regulatory Aspects 2010-11-29 doi: 10.3390/pharmaceutics2040364 Jochen Zisowsky Andreas Krause Jasper Dingemanse http://www.mdpi.com/1999-4923/2/4/351 Standard compendia dissolution apparatus are the first choice for development of new dissolution methods. Nevertheless, limitations coming from the amount of material available, analytical sensitivity, lack of discrimination or biorelevance may warrant the use of non compendial methods. In this regard, the use of small volume dissolution methods offers strong advantages. The present study aims primarily to evaluate the dissolution performance of various drug products having different release mechanisms, using commercially available small volume USP2 dissolution equipment. The present series of tests indicate that the small volume dissolution is a useful tool for the characterization of immediate release drug product. Depending on the release mechanism, different speed factors are proposed to mimic common one liter vessel performance. In addition, by increasing the discriminating power of the dissolution method, it potentially improves know how about formulations and on typical events which are evaluated during pharmaceutical development such as ageing or scale–up. In this regard, small volume dissolution is a method of choice in case of screening for critical quality attributes of rapidly dissolving tablets, where it is often difficult to detect differences using standard working conditions. http://www.mdpi.com/1999-4923/2/4/351 Mon, 01 Nov 2010 00:00:00 CET Pharmaceutics 2010-11-01 2 4 Article 351 363 1999-4923 Small Volume Dissolution Testing as a Powerful Method during Pharmaceutical Development 2010-11-01 doi: 10.3390/pharmaceutics2040351 Emmanuel Scheubel Marc Lindenberg Eric Beyssac Jean-Michel Cardot http://www.mdpi.com/1999-4923/2/4/339 Several biologically relevant phospholipids were assessed as potential carriers/additives for rapidly dissolving solid formulations of piroxicam (Biopharmaceutics Classification System Class II drug). On the basis of in vitro dissolution studies, dimyristoylphosphatidylglycerol (DMPG) was ranked as the first potent dissolution rate enhancer for the model drug. Subsequently, the solid dispersions of varying piroxicam/DMPG ratios were prepared and further investigated. Within the concentration range studied (6.4-16.7 wt %), the dissolution rate of piroxicam from the solid dispersions appeared to increase as a function of the carrier weight fraction, whereas the cumulative drug concentration was not significantly affected by piroxicam/DMPG ratio, presumably due to a unique phase behavior of the aqueous dispersions of this carrier phospholipid. Solid state analysis of DMPG-based formulations reveled that they are two-component systems, with a less thermodynamically stable form of piroxicam (Form II) being dispersed within the carrier. Finally, oral bioavailability of piroxicam from the DMPG-based formulations in rats was found to be superior to that of the control, as indicated by the bioavailability parameters, cmax and especially Tmax (53 µg/mL within 2 h vs. 39 µg/mL within 5.5 h, respectively). Hence, DMPG was regarded as the most promising carrier phospholipid for enhancing oral bioavailability of piroxicam and potentially other Class II drugs. http://www.mdpi.com/1999-4923/2/4/339 Wed, 27 Oct 2010 00:00:00 CEST Pharmaceutics 2010-10-27 2 4 Article 339 350 1999-4923 Enhanced Dissolution and Oral Bioavailability of Piroxicam Formulations: Modulating Effect of Phospholipids 2010-10-27 doi: 10.3390/pharmaceutics2040339 Sabiruddin Mirza Inna Miroshnyk Muhammad J. Habib James F. Brausch Muhammad D. Hussain http://www.mdpi.com/1999-4923/2/4/321 Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age. http://www.mdpi.com/1999-4923/2/4/321 Thu, 14 Oct 2010 00:00:00 CEST Pharmaceutics 2010-10-14 2 4 Article 321 338 1999-4923 Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny 2010-10-14 doi: 10.3390/pharmaceutics2040321 Binbing Ling Caroline Aziz Chris Wojnarowicz Andrew Olkowski Jane Alcorn http://www.mdpi.com/1999-4923/2/3/313 Application of oral fast release amantadine and levodopa may induce an improvement of motor symptoms in patients with Parkinson’s disease (PD). The objective of this trial was to investigate the clinical efficacy of a fast release amantadine sulfate formulation on simple and complex movement performance and putative relations to the pharmacokinetic behavior in PD patients. We challenged two cohorts of 12 PD patients, who were taken off their regular antiparkinsonian treatment for at least 12 hours, with oral 300 mg amantadine sulfate. We scored motor symptoms and performed instrumental tasks, which ask for performance of simple or complex motion series under cued conditions. Motor symptoms and performance of complex movements significantly improved in contrast to the carrying-out of simple motions. N-methyl-D-aspartic acid antagonistic and dopaminomimetic amantadine also influences altered higher predominant prefrontal cognitive functions. Therefore, performance of complex motion series improved, whereas carrying-out of simple repetitive movements is more associated to the striatal dopamine dependent basal ganglia function. http://www.mdpi.com/1999-4923/2/3/313 Mon, 20 Sep 2010 00:00:00 CEST Pharmaceutics 2010-09-20 2 3 Article 313 320 1999-4923 Impact of Oral Fast Release Amantadine on Movement Performance in Patients with Parkinson’s Disease 2010-09-20 doi: 10.3390/pharmaceutics2030313 Siegfried Muhlack Patricia Müsch Sandra Konietzka Dirk Woitalla Horst Przuntek Thomas Müller http://www.mdpi.com/1999-4923/2/3/300 This study investigated gene expression of drug resistance factors in biopsy tissue samples from hepatocellular carcinoma (HCC) patients undergoing chemotherapy by platinum complex. Liver biopsy was performed to collect tissue from the tumor site (T) and the non-tumor site (NT) prior to the start of treatment. For drug-resistant factors, drug excretion transporters cMOAT and MDR-1, intracellular metal binding protein MT2, DNA repair enzyme ERCC-l and inter-nucleic cell transport protein MVP, were investigated. The comparison of the expression between T and NT indicated a significant decrease of MT2 and MDR-1 in T while a significant increase in ERCC-1 was noted in T. Further, expression was compared between the response cases and non-response cases using the ratios of expression in T to those in NT. The response rate was significantly low in the high expression group when the cutoff value of cMOAT and MT2 was set at 1.5 and 1.0, respectively. Furthermore, when the patients were classified into A group (cMOAT ≧ 1.5 or MT2 ≧ 1.0) and B group (cMOAT < 1.5 and MT2 < 1.0), the response rate of A group was significantly lower than B group when we combined the cutoff values of cMOAT and MT2. It is considered possible to estimate the therapeutic effect of platinum complex at a high probability by combining the expression condition of these two genes. http://www.mdpi.com/1999-4923/2/3/300 Thu, 09 Sep 2010 00:00:00 CEST Pharmaceutics 2010-09-09 2 3 Article 300 312 1999-4923 Expression of Drug-Resistant Factor Genes in Hepatocellular Carcinoma Patients Undergoing Chemotherapy with Platinum Complex by Arterial Infusion 2010-09-09 doi: 10.3390/pharmaceutics2030300 Tomoya Sakurada Masaharu Yoshikawa Masahiko Sunaga Eriko Kobayashi Nobunori Satoh Osamu Yokosuka Shiro Ueda http://www.mdpi.com/1999-4923/2/3/291 Tacrolimus is a calcineurin inhibitor immunosuppressant that has seen considerable use in both adult and pediatric solid organ transplant recipients. Though there is much pharmacokinetic data available for tacrolimus in the adult population, the literature available for children is limited. Furthermore, very little is known about the pharmacogenomic differences in the two patient groups. Based on what information is currently available, clinically significant differences may exist between the two populations in terms of absorption, distribution, metabolism and elimination. In addition, inherent physiological differences exist in the young child including: less effective plasma binding proteins, altered expression of intestinal P-glycoprotein, and increased expression of phase 1 metabolizing enzymes, therefore one would expect to see clinically significant differences when administering tacrolimus to a child. This paper examines available literature in an attempt to summarize the potential pharmacokinetic and pharmacogenomic variability that exists between the two populations. http://www.mdpi.com/1999-4923/2/3/291 Thu, 09 Sep 2010 00:00:00 CEST Pharmaceutics 2010-09-09 2 3 Review 291 299 1999-4923 Tacrolimus Pharmacokinetic and Pharmacogenomic Differences between Adults and Pediatric Solid Organ Transplant Recipients 2010-09-09 doi: 10.3390/pharmaceutics2030291 Kwaku Marfo Jerry Altshuler Amy Lu http://www.mdpi.com/1999-4923/2/3/275 Powder flow is influenced by environmental factors, such as moisture and static electricity, as well as powder related factors, such as morphology, size, size distribution, density, and surface area. Pharmaceutical solids may be exposed to water during storage in an atmosphere containing water vapor, or in a dosage form consisting of materials (e.g., excipients) that contain water and are capable of transferring in to other ingredients. The effect of moisture on powder flowability depends on the amount of water and its distribution. The aim of this work was to examine the effect of humidity on the flow properties of theophylline using information derived from solid-state analysis of the systems investigated. http://www.mdpi.com/1999-4923/2/3/275 Fri, 02 Jul 2010 00:00:00 CEST Pharmaceutics 2010-07-02 2 3 Article 275 290 1999-4923 Effect of Moisture on Powder Flow Properties of Theophylline 2010-07-02 doi: 10.3390/pharmaceutics2030275 Sandler Reiche Heinämäki Yliruusi http://www.mdpi.com/1999-4923/2/2/258 Pharmacokinetic interactions, e.g. modulation of drug transporters like P-glycoprotein at the blood-brain barrier, can be a reason for treatment non-response. This study focuses on the influence of induction of drug transporters on the disposition of the antipsychotic drugs risperidone and 9-hydroxyrisperidone. Brain and serum concentrations of risperidone and its active metabolite 9-hydroxyrisperidone, which are known P-glycoprotein substrates, were measured after drug transporter induction with rifampicin, dexamethasone or 5-pregnene-3beta-ol-20-on-16alpha-carbonitrile using high performance liquid chromatography. Disposition of risperidone and 9-hydroxyrisperidone was dramatically decreased in mouse brain and serum after drug transporter induction. The metabolism of risperidone was also affected. http://www.mdpi.com/1999-4923/2/2/258 Wed, 02 Jun 2010 00:00:00 CEST Pharmaceutics 2010-06-02 2 2 Article 258 274 1999-4923 Induction of Drug Transporters Alters Disposition of Risperidone - A Study in Mice 2010-06-02 doi: 10.3390/pharmaceutics2020258 Holthoewer Hiemke Schmitt http://www.mdpi.com/1999-4923/2/2/245 The antioxidant properties of different low molecular weight (LMW) chitosans (CS1; 22 kDa, CS2; 38 kDa, CS3; 52 kDa, CS4; 81 kDa) were examined for possible use in extended-release tablets. The criteria used were the ability of the chitosans to reduce Cu2+, and hydroxyl and superoxide radicals and N-centered radicals derived from 1,1\'-diphenyl-2-picrylhydrazyl, via the use of ESR spectrometry. CS2 showed the highest scavenging activity. CS1 and CS3, however, were much less effective and CS4 was not a viable antioxidant. The results suggest that CS2 could be useful in combating the development of oxidative stress. A series of chitosan tablets were prepared using a spray drying method and evaluated as an extended-release matrix tablet using theophylline (TPH) as a model drug. The release of TPH from the different MW chitosan tablets increased with increasing MW of the chitosan used. CS2, CS3 and CS4 showed a reasonable release activity, but CS1 showed the shortest release activity. Moreover, the CS2-TPH tablet showed the highest scavenging activity of the three chitosan tablets (CS2-CS4) using 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radicals. These results suggest that a CS2-TPH tablet could be potentially useful in an extended-release matrix tablet with a high antioxidant activity. http://www.mdpi.com/1999-4923/2/2/245 Thu, 27 May 2010 00:00:00 CEST Pharmaceutics 2010-05-27 2 2 Article 245 257 1999-4923 Useful Extend-release Chitosan Tablets with High Antioxidant Activity 2010-05-27 doi: 10.3390/pharmaceutics2020245 Yasufuku Anraku Kondo Hata Hirose Kobayashi Tomida http://www.mdpi.com/1999-4923/2/2/224 Configurational entropy is an important parameter in amorphous systems. It is involved in the thermodynamic considerations, plays an important role in the molecular mobility calculations through its appearance in the Adam-Gibbs equation and provides information on the solubility increase of an amorphous form compared to its crystalline counterpart. This paper presents a calorimetric method which enables the scientist to quickly determine the values for the configurational entropy at any temperature and obtain the maximum of information from these measurements. http://www.mdpi.com/1999-4923/2/2/224 Tue, 25 May 2010 00:00:00 CEST Pharmaceutics 2010-05-25 2 2 Article 224 244 1999-4923 The Role of Configurational Entropy in Amorphous Systems 2010-05-25 doi: 10.3390/pharmaceutics2020224 Graeser Patterson Zeitler Rades http://www.mdpi.com/1999-4923/2/2/209 Synthetic membranes used in Franz diffusion cells for topical formulation quality assessment should provide least resistance to drug diffusion. In this study, the diffusion rates of ibuprofen across thirteen membranes were determined using Franz diffusion cells. Correlation of the membrane thickness, pore size and MWCO with drug fluxes was also made. The drug diffusion results showed that the porous membranes were categorized into high-flux (8–18 mg/cm2/h) and low-flux (0.1–3 mg/cm2/h) membranes. The drug fluxes did not show strong correlations (r2 < 0.99) with membrane parameters. Synthetic membranes can give variable drug fluxes, thus investigators should be careful in choosing membrane for formulation quality assessment. http://www.mdpi.com/1999-4923/2/2/209 Tue, 18 May 2010 00:00:00 CEST Pharmaceutics 2010-05-18 2 2 Article 209 223 1999-4923 A Comparative Study of Transmembrane Diffusion and Permeation of Ibuprofen across Synthetic Membranes Using Franz Diffusion Cells 2010-05-18 doi: 10.3390/pharmaceutics2020209 Ng Rouse Sanderson Eccleston http://www.mdpi.com/1999-4923/2/2/199 The objective of this study was to demonstrate that asymmetric membrane capsules can be used to deliver a poorly water soluble drug with a pH dependent solubility, such as carvedilol, for extended periods of time by modulating solubility with acid. In this study, the effect of the concentration of pH regulating agent and osmotic agents on the release rate of the active material was investigated. For this purpose, asymmetric membrane capsules of carvedilol were prepared using cellulose acetate as a semi-permeable membrane, containing glycerol as plasticizer, and fructose and fumaric acid were used as osmotic agent and pH regulating agent, respectively. In osmotic systems, the release rate of an excipient relative to the release rate of the drug is an important factor that determines the duration of drug release. Owing to high acidic strength and low aqueous solubility, fumaric acid resulted in simultaneous release and maintained a constant micro-environmental condition for the dissolution of the weakly basic drug. Finally, it was observed that the release rate of carvedilol was influenced by the concentration of fumaric acid and fructose. The optimal formulation was found to be able to deliver carvedilol at the rate of approximate zero-order up to 20 h, independent of release media and agitation rate. http://www.mdpi.com/1999-4923/2/2/199 Tue, 18 May 2010 00:00:00 CEST Pharmaceutics 2010-05-18 2 2 Article 199 208 1999-4923 Asymmetric Membrane Capsules for Extended Delivery of the Weakly Basic Drug Carvedilol 2010-05-18 doi: 10.3390/pharmaceutics2020199 Guarve Gupta http://www.mdpi.com/1999-4923/2/2/182 An artificial neural network was used to optimize the release of salbutamol sulfate from hydrophilic matrix formulations. Model formulations to be used for training, testing and validating the neural network were manufactured with the aid of a central composite design with varying the levels of Methocel® K100M, xanthan gum, Carbopol® 974P and Surelease® as the input factors. In vitro dissolution time profiles at six different sampling times were used as target data in training the neural network for formulation optimization. A multi layer perceptron with one hidden layer was constructed using Matlab®, and the number of nodes in the hidden layer was optimized by trial and error to develop a model with the best predictive ability. The results revealed that a neural network with nine nodes was optimal for developing and optimizing formulations. Simulations undertaken with the training data revealed that the constructed model was useable. The optimized neural network was used for optimization of formulation with desirable release characteristics and the results indicated that there was agreement between the predicted formulation and the manufactured formulation. This work illustrates the possible utility of artificial neural networks for the optimization of pharmaceutical formulations with desirable performance characteristics. http://www.mdpi.com/1999-4923/2/2/182 Thu, 06 May 2010 00:00:00 CEST Pharmaceutics 2010-05-06 2 2 Article 182 198 1999-4923 Optimization of Salbutamol Sulfate Dissolution from Sustained Release Matrix Formulations Using an Artificial Neural Network 2010-05-06 doi: 10.3390/pharmaceutics2020182 Chaibva Burton Walker http://www.mdpi.com/1999-4923/2/2/171 A fully automated 96-well On-Line Solid Phase Extraction (SPE) followed by High Performance Liquid Chromatography (HPLC)-Tandem Mass Spectrometric (MS/MS) method for the determination of ABT-925 (2-{3-[4-(2-tert-Butyl-6-trifluoromethyl-pyrimidin-4-yl)-piperazin-1-yl)-propyl-sulfanyl}-3H-pyrimidin-4-one fumarate) in human plasma was developed, validated and utilized in Phase II clinical studies. 50 µL of plasma sample was fortified with internal standard (IS, d8-ABT-925) and extracted on-line with Cohesive Turbo Flow Cyclone P HTLC column. The chromatographic separation was performed on Aquasil C18 (3 μm 50 × 3 mm) HPLC column with a mobile phase consisting of 50/50/0.1 (v/v/v) ACN/H2O/formic acid. The mass spectrometric measurement was conducted under positive ion mode using multiple reaction monitoring (MRM) of m/z 457.4 → 329.4 for analyte and m/z 465.5 → 337.5 for IS.The peak area ratio (analyte/IS) was used to quantitate ABT-925. A dynamic range of 0.0102 μg/mL to 5.24 μg/mL was established after the validation. The validated method was then used for two Phase II studies. To demonstrate the method reproducibility, approximately 10% of the incurred samples from one study were repeated in singlet. The repeated values were compared to the initial values. All repeated values agreed within ±15% of the mean values. http://www.mdpi.com/1999-4923/2/2/171 Tue, 04 May 2010 00:00:00 CEST Pharmaceutics 2010-05-04 2 2 Article 171 181 1999-4923 Quantitative Determination of ABT-925 in Human Plasma by On-Line SPE and LC-MS/MS: Validation and Sample Analysis in Phase II Studies 2010-05-04 doi: 10.3390/pharmaceutics2020171 Wan Rieser El-Shourbagy http://www.mdpi.com/1999-4923/2/2/159 When compared with biological samples in other matrices (plasma, urine, etc.) that are typically seen in bioanalytical applications, whole blood samples present unique challenges in method development, because of the viscous nature of blood and complexity of its constituents. In this article, we have developed and validated a series of quantitative bioanalytical methods for the determination of a pharmaceutical compound, Compound A, and its phosphate metabolite from whole blood matrices using liquid chromatography tandem mass spectrometry. All methods employed a simple protein precipitation procedure that was automated in 96-well format. The methods were subjected to vigorous tests in precision, accuracy, matrix effect, reproducibility, and robustness. Monolithic chromatography was used to improve sample throughput in one of the methods. The results also demonstrated that proper sample preparation procedures, such as sample transfer and lysing of blood cells prior to the extraction, are key to reproducible results for pharmacokinetic parameter determination. http://www.mdpi.com/1999-4923/2/2/159 Fri, 30 Apr 2010 00:00:00 CEST Pharmaceutics 2010-04-30 2 2 Article 159 170 1999-4923 Strategies for Developing Sensitive and Automated LC-MS/MS Assays of a Pharmaceutical Compound and Its Metabolite from Whole Blood Matrix 2010-04-30 doi: 10.3390/pharmaceutics2020159 Xu Polzin Kranz Vaca Metchkarova Rieser El-Shourbagy http://www.mdpi.com/1999-4923/2/2/136 Nine diclofenac salts prepared with alkyl-hydroxy amines were analyzed for their properties to form polymorphs by DSC and HSM techniques. Thermograms of the forms prepared from water or acetone are different in most cases, suggesting frequent examples of polymorphism among these salts. Polymorph transition can be better highlighted when analysis is carried out by thermo-microscopy, which in most cases made it possible to observe the processes of melting of the metastable form and re-crystallization of the stable one. Solubility values were qualitatively related to the crystal structure of the salts and the molecular structure of the cation. http://www.mdpi.com/1999-4923/2/2/136 Tue, 27 Apr 2010 00:00:00 CEST Pharmaceutics 2010-04-27 2 2 Article 136 158 1999-4923 Diclofenac Salts. V. Examples of Polymorphism among Diclofenac Salts with Alkyl-hydroxy Amines Studied by DSC and HSM 2010-04-27 doi: 10.3390/pharmaceutics2020136 Fini Cavallari Ospitali http://www.mdpi.com/1999-4923/2/2/119 In this study, magnetic iron oxide nanoparticles coated with heparin (Hep-MION) were synthesized and the transcellular transport of the nanoparticles across epithelial cell monolayers on porous polyester membranes was investigated. An externally applied magnetic field facilitated the transport of the Hep-MION across cell monolayers. However, high Hep-MION concentrations led to an increased aggregation of nanoparticles on the cell monolayer after application of the magnetic field. Our results indicate that magnetic guidance of Hep-MION most effectively promotes transcellular transport under conditions that minimize formation of magnetically-induced nanoparticle aggregates. Across cell monolayers, the magnet’s attraction led to the greatest increase in mass transport rate in dilute dispersions and in high serum concentrations, suggesting that magnetic guidance may be useful for in vivo targeting of Hep-MION. http://www.mdpi.com/1999-4923/2/2/119 Mon, 26 Apr 2010 00:00:00 CEST Pharmaceutics 2010-04-26 2 2 Article 119 135 1999-4923 Transcellular Transport of Heparin-coated Magnetic Iron Oxide Nanoparticles (Hep-MION) Under the Influence of an Applied Magnetic Field 2010-04-26 doi: 10.3390/pharmaceutics2020119 Min Yu Yang Zhang Rosania http://www.mdpi.com/1999-4923/2/2/105 A novel bioanalytical method was developed and validated for the quantitative determination of erlotinib in human plasma by using the supported liquid extraction (SLE) sample cleanup coupled with hydrophilic interaction liquid chromatography and tandem mass spectrometric detection (HILIC-MS/MS). The SLE extract could be directly injected into the HILIC-MS/MS system for analysis without the solvent evaporation and reconstitution steps. Therefore, the method is simple and rapid. In the present method, erlotinib-d6 was used as the internal standard. The SLE extraction recovery was 101.3%. The validated linear curve range was 2 to 2,000 ng/mL based on a sample volume of 0.100-mL, with a linear correlation coefficient of > 0.999. The validation results demonstrated that the present method gave a satisfactory precision and accuracy: intra-day CV < 5.9% ( http://www.mdpi.com/1999-4923/2/2/105 Thu, 01 Apr 2010 00:00:00 CEST Pharmaceutics 2010-04-01 2 2 Article 105 118 1999-4923 Automatic Supported Liquid Extraction (SLE) Coupled with HILIC-MS/MS: An Application to Method Development and Validation of Erlotinib in Human Plasma 2010-04-01 doi: 10.3390/pharmaceutics2020105 Pan Jiang Chen http://www.mdpi.com/1999-4923/2/2/91 A relatively simple and effective method to follow the movement of pharmaceutical preparations such as vaccines in biodistribution studies is to radiolabel the components. Whilst single radiolabelling is common practice, in vaccine systems containing adjuvants the ability to follow both the adjuvant and the antigen is favourable. To this end, we have devised a dual-radiolabelling method whereby the adjuvant (liposomes) is labelled with 3H and the antigen (a subunit protein) with 125I. This model is stable and reproducible; we have shown release of the radiolabels to be negligible over periods of up to 1 week in foetal calf serum at 37 ºC. In this paper we describe the techniques which enable the radiolabelling of various components, assessing stability and processing of samples which all for their application in biodistribution studies. Furthermore we provide examples derived from our studies using this model in tuberculosis vaccine biodistribution studies. http://www.mdpi.com/1999-4923/2/2/91 Wed, 31 Mar 2010 00:00:00 CEST Pharmaceutics 2010-03-31 2 2 Article 91 104 1999-4923 Radiolabelling of Antigen and Liposomes for Vaccine Biodistribution Studies 2010-03-31 doi: 10.3390/pharmaceutics2020091 Henriksen-Lacey Bramwell Perrie http://www.mdpi.com/1999-4923/2/2/78 Foods and pharmaceuticals materials are exposed to various environmental conditions during processing and while in storage; therefore, stability and quality are key attributes of concern. The properties of foods and pharmaceutical materials that define their quality are affected by conditions such as temperature, humidity and time. Glass transition is considered a key material property to understand how these external conditions affect the stability and quality of foods and pharmaceuticals. Thus, investigating the thermo-mechanical properties of these materials as well as characterizing the glass transition temperature have a great interest not only in the food industry, but also extend to the pharmaceutical and polymer industries. The aim of this study was to design and test a new disposable powder holder that allows the use of a dynamic mechanical analysis (DMA) instrument to test and characterize loose powder samples. The disposable aluminum powder holder was designed and constructed to be used in the single cantilever configuration on a TA Instruments RSA III DMA. Three different powder samples – Felodipine, polyethylene-oxide (MW 900 kDa) and HPMC (E4M) – were used for validation. The use of this powder holder allows the detection of different thermal changes of powder samples without compacting and when large sample size is necessary for detection and/or interpretation. http://www.mdpi.com/1999-4923/2/2/78 Wed, 24 Mar 2010 00:00:00 CET Pharmaceutics 2010-03-24 2 2 Article 78 90 1999-4923 Assessment of Thermal Transitions by Dynamic Mechanical Analysis (DMA) Using a Novel Disposable Powder Holder 2010-03-24 doi: 10.3390/pharmaceutics2020078 Abiad Campanella Carvajal http://www.mdpi.com/1999-4923/2/1/61 The effect of Pgp induction in rats by pregnenolone 16α-carbonitrile (PCN) (3 days, 35 mg/kg/d, p.o.) on digoxin pharmacokinetics and intestinal transport has been assessed. After intravenous or oral digoxin dosing the arterial and hepatic portal vein (oral) AUC(0-24h) were significantly reduced by PCN pre-treatment. Biliary digoxin clearance increased 2-fold following PCN treatment. PCN significantly increased net digoxin secretion (2.05- and 4.5-fold respectively) in ileum and colon but not in duodenum or jejunum. This increased secretion correlated with increased Pgp protein expression in ileum and colon. Both intestinal and biliary excretion therefore contribute to altered digoxin disposition following PCN. http://www.mdpi.com/1999-4923/2/1/61 Mon, 15 Mar 2010 00:00:00 CET Pharmaceutics 2010-03-15 2 1 Article 61 77 1999-4923 The Effects of Pregnenolone 16α-Carbonitrile Dosing on Digoxin Pharmacokinetics and Intestinal Absorption in the Rat 2010-03-15 doi: 10.3390/pharmaceutics2010061 Lowes Haslam Fihn Hilgendorf Karlsson Simmons Ungell http://www.mdpi.com/1999-4923/2/1/50 Label claims of vitamin E succinate and polyphenolic nutraceuticals are assessed. A validated HPLC method was utilized to assess vitamin E succinate products. Three novel LC/MS methods were used to assess the polyphenols, pterostilbene, phloretin, and myricetin, in dietary supplements. The amount of vitamin E succinate varied from 0-130% of the stated label content with two products containing vitamin E acetate rather than vitamin E succinate. Expected polyphenols were found in 7 of the 8 supplement products. None of the polyphenol supplements contained content within 100-120% of label claims. The present study indicates a lack of uniformity in nutraceutical products. http://www.mdpi.com/1999-4923/2/1/50 Mon, 08 Mar 2010 00:00:00 CET Pharmaceutics 2010-03-08 2 1 Article 50 60 1999-4923 Ingredient Consistency of Commercially Available Polyphenol and Tocopherol Nutraceuticals 2010-03-08 doi: 10.3390/pharmaceutics2010050 Connie M. Remsberg Renee L. Good Neal M. Davies http://www.mdpi.com/1999-4923/2/1/30 The aim of this study was to compare three different analytical methods to detect and quantify the amount of crystalline disorder/ amorphousness in two milled model drugs. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and Raman spectroscopy were used as analytical methods and indomethacin and simvastatin were chosen as the model compounds. These compounds partly converted from crystalline to disordered forms by milling. Partial least squares regression (PLS) was used to create calibration models for the XRPD and Raman data, which were subsequently used to quantify the milling-induced crystalline disorder/ amorphousness under different process conditions. In the DSC measurements the change in heat capacity at the glass transition was used for quantification. Differently prepared amorphous indomethacin standards (prepared by either melt quench cooling or cryo milling) were compared by principal component analysis (PCA) to account for the fact that the choice of standard ultimately influences the quantification outcome. Finally, the calibration models were built using binary mixtures of crystalline and quench cooled amorphous drug materials. The results imply that the outcome with respect to crystalline disorder for milled drugs depends on the analytical method used and the calibration standard chosen as well as on the drug itself. From the data presented here, it appears that XRPD tends to give a higher percentage of crystalline disorder than Raman spectroscopy and DSC for the same samples. For the samples milled under the harshest milling conditions applied (60 min, sixty 4 mm balls, 25 Hz) a crystalline disorder/ amorphous content of 44.0% (XRPD), 10.8% (Raman spectroscopy) and 17.8% (DSC) were detected for indomethacin. For simvastatin 18.3% (XRPD), 15.5% (Raman spectroscopy) and 0% (DSC, no glass transition) crystalline disorder/ amorphousness were detected. http://www.mdpi.com/1999-4923/2/1/30 Tue, 16 Feb 2010 00:00:00 CET Pharmaceutics 2010-02-16 2 1 Article 30 49 1999-4923 Quantification of Process Induced Disorder in Milled Samples Using Different Analytical Techniques 2010-02-16 doi: 10.3390/pharmaceutics2010030 Ulrike Zimper Jaakko Aaltonen Cushla M. McGoverin Keith C. Gordon Karen Krauel-Goellner Thomas Rades http://www.mdpi.com/1999-4923/2/1/18 Levels of reactive γ-ketoaldehydes derived from arachidonate increase in diseases associated with inflammation and oxidative injury. To assess the biological importance of these γ-ketoaldehydes, we previously identified salicylamine as an effective γ-ketoaldehyde scavenger in vitro and in cells. To determine if salicylamine could be administered in vivo, we developed an LC/MS/MS assay to measure salicylamine in plasma and tissues. In mice, half-life (t1/2) was 62 minutes. Drinking water supplementation (1-10 g/L) generated tissue concentrations (10-500 μM) within the range previously shown to inhibit γ-ketoaldehydes in cells. Therefore, oral administration of salicylamine can be used to assess the contribution of γ-ketoaldehydes in animal models of disease. http://www.mdpi.com/1999-4923/2/1/18 Mon, 01 Feb 2010 00:00:00 CET Pharmaceutics 2010-02-01 2 1 Article 18 29 1999-4923 Determination of the Pharmacokinetics and Oral Bioavailability of Salicylamine, a Potent γ-Ketoaldehyde Scavenger, by LC/MS/MS 2010-02-01 doi: 10.3390/pharmaceutics2010018 Irene Zagol-Ikapitte Elena Matafonova Venkataraman Amarnath Christopher L. Bodine Olivier Boutaud Rommel G. Tirona John A. Oates L. Jackson Roberts II Sean S. Davies http://www.mdpi.com/1999-4923/2/1/1 Lyophilised orally disintegrating tablets (ODTs) have achieved a great success in overcoming dysphagia associated with conventional solid dosage forms. However, the extensive use of saccharides within the formulation limits their use in treatment of chronic illnesses. The current study demonstrates the feasibility of using combination of proline and serine to formulate zero sacharide ODTs and investigates the effect of freezing protocol on sublimation rate and tablets characteristics. The results showed that inclusion of proline and serine improved ODT properties when compared to individual counterparts. Additionally, annealing the ODTs facilitated the sublimation process and shortened the disintegration time. http://www.mdpi.com/1999-4923/2/1/1 Mon, 04 Jan 2010 00:00:00 CET Pharmaceutics 2010-01-04 2 1 Article 1 17 1999-4923 Investigation of Formulation and Process of Lyophilised Orally Disintegrating Tablet (ODT) Using Novel Amino Acid Combination 2010-01-04 doi: 10.3390/pharmaceutics2010001 Farhan AlHusban Amr M. ElShaer Jiteen H. Kansara Alan M. Smith Liam M. Grover Yvonne Perrie Afzal R. Mohammed http://www.mdpi.com/1999-4923/1/1/3 Six mixtures, containing 10, 20 and 30% w/w ibuprofen and isomalt, were compacted by a traditional or ultrasound-assisted machine and analysed by means of thermal (DSC and TGA) and micro-spectrometry (Raman and FT-IR) techniques. Ultrasound discharge causes melting of ibuprofen powder, transforming into a paste that could not assume the shape of a tablet; when in mixture with isomalt, thermal events, occurring during ultrasound compaction, change the appearance of the particles formed by milling the tablets obtained this way and SEM photos reveal a dramatic reduction of the particle size and changes due to a possible ibuprofen re-crystallization. Raman and FT-IR spectra of small portions of the surface and of the bulk, using characteristic peaks for identification, reveal that in ultrasound-compacted tablets ibuprofen partially disappears from the top face of the tablet. http://www.mdpi.com/1999-4923/1/1/3 Fri, 09 Oct 2009 00:00:00 CEST Pharmaceutics 2009-10-09 1 1 Article 3 19 1999-4923 Effect of Ultrasound on the Compaction of Ibuprofen/Isomalt Systems 2009-10-09 doi: 10.3390/pharmaceutics1010003 Adamo Fini Cristina Cavallari Francesca Ospitali http://www.mdpi.com/1999-4923/1/1/1 We know the many hurdles that face us when we look to deliver a drug, starting from the basic characteristics of the drug (its solubility, stability, absorption and biodistribution), to overcoming the physiological barriers faced in reaching the target site, and to maintaining the concentration within the therapeutic window. In addition we must also remember the patient needs in this – is it a child that needs a liquid dosage form? Is it someone having to take multiple doses in a day? Do we need a rapid onset of action in a convenient format? Will people find it convenient to take the drug in the format we are presenting to them – or are there alternative options? [...] http://www.mdpi.com/1999-4923/1/1/1 Fri, 02 Oct 2009 00:00:00 CEST Pharmaceutics 2009-10-02 1 1 Editorial 1 2 1999-4923 Pharmaceutics: A New Open-Access Journal for All Those Interested in Designing Medicines 2009-10-02 doi: 10.3390/pharmaceutics1010001 Yvonne Perrie Afzal R. Mohammed