Table of Contents

Abstract: 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.

Abstract: 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.

Abstract: 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% (<8.4% for the lower limit of quantitation, LLOQ) with n = 6 and the accuracy of 98.0–106.0%; inter-day CV < 3.2% (<1.5% for LLOQ) with n = 18 and the accuracy of 100.0–103.2%. A dilution factor of 10 with blank plasma was validated for partial volume analysis. The stability tests indicated that the erlotinib in human plasma is stable for three freeze-thaw cycles (100.0–104.5% of the nominal values), or 24-h ambient storage (100.0–104.8% of the nominal values), or 227-day frozen storage at both -20 ºC (91.5–94.5% of the nominal values) and -70 ºC (93.3–93.8% of the nominal values). The results also showed no significant matrix effect (<6.3%) even with direct injection of organic extract into the LC-MS/MS system. The validated method has been successfully applied to support a clinical study.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.