Search Results (53)

Background: To repurpose carbutamide (CBT), a discontinued sulfonylurea-class anti-diabetic drug, as an anti-inflammatory bowel disease (IBD) drug, CBT azo-linked with salicylic acid (CAA) was designed and synthesized as a colon-specific prodrug to co-release CBT and mesalazine (5-ASA) selectively in the large intestine. Methods: CAA exhibited reduced lipophilicity and decreased transintestinal transport compared to CBT, as shown in an ex vivo experiment using isolated rat jejunal segments. It also underwent cleavage into CBT and 5-ASA when incubated with cecal contents of rats. Additionally, oral administration of CAA and Sulfasalazine (SSZ), a colon-specific prodrug of 5-ASA currently used for IBD treatment, resulted in similar levels of 5-ASA accumulation in the rat cecal region. Results: In a dinitrobenzene sulfonic acid-triggered colitis model in rats, CAA produced a more pronounced improvement in colon injury and inflammation than SSZ. Furthermore, rectal co-administration of CBT and 5-ASA conferred enhanced protective outcomes compared to monotherapy with either agent alone, suggesting a combined anticolitic action. The two drugs also jointly suppressed valacyclovir uptake via peptide transporter 1 (PepT1) in the distal colon, supporting PepT1 as a target contributing to their combined anticolitic effect. Unlike CBT, which significantly reduced blood glucose following oral administration, equimolar administration of CAA did not alter glycemic levels, consistent with reduced systemic exposure to CBT. Conclusions: In conclusion, CAA functions as a colon-specific mutual prodrug that surpasses SSZ in anticolitic performance while minimizing hypoglycemia risk, thus facilitating the repurposing of CBT as a treatment for IBD. Full article

Background/Objectives: The drug development response to the unique pharmacology of fentanyl, which drives the current opioid epidemic, has primarily focused on increasing naloxone doses and employing longer-acting antidotes. While having lower withdrawal liability, the commonly perceived disadvantage of naloxone is its reduced effectiveness against re-narcotization or “fentanyl rebound,” due to a significant mismatch between its half-life (t_1/2) and that of fentanyl. Methods: We conducted a pharmacokinetic profile (PK) crossover study in fentanyl-sedated dogs to assess naloxone (NX) and its lipophilic prodrug (NX90) with regard to fentanyl PK and re-narcotization risk. Results: Our findings showed that naloxone redistributed fentanyl into the plasma, with correlating (R² = 0.9121) fentanyl and naloxone plasma levels when seven plasma samples per dog for each treatment (including placebo) were analyzed. This redistribution led to reductions in fentanyl’s volume of distribution at steady state (V_ss: 11.8 ± 1.7, 8.4 ± 2.4, and 8.7 ± 2.6 L/kg), mean residence time (MRT: 19.9 ± 1.8, 18.6 ± 7.2, and 16.2 ± 8.8 min), and half-life (t_1/2: 14.3 ± 1.9, 13.0 ± 4.9, and 11.2 ± 6.1 min) after the administration of a placebo, NX, and NX90, respectively. Additionally, we observed that the delay in the transient re-sedation (re-narcotization) of the dogs correlated (R² = 0.794) with naloxone’s exposure (AUC_inf). These data suggest that (i) the displacement of fentanyl into a metabolically active compartment and (ii) the delay in re-narcotization risk are both independent of naloxone’s half-life and are likely to be more effectively achieved with higher doses of naloxone. Conclusions: Combined with the lower risk of precipitating protracted withdrawal, these findings support the clinical use of higher-dose naloxone over longer-acting antidotes for reversing fentanyl-related overdoses. Full article

One of the main limitations of photodynamic therapy (PDT) is hypoxia, which is caused by increased tumour proliferation creating a hypoxic tumour microenvironment (TME), as well as oxygen consumption by PDT. Hypoxia-activated prodrugs (HAPs), such as molecules containing aliphatic or aromatic N-oxide functionalities, are non-toxic prodrugs that are activated in hypoxic regions, where they are reduced into their cytotoxic form. The (oxido)pyridylporphyrins tested in this work were synthesised as potential HAPs from their AB₃ pyridylporphyrin precursors, using m-chloroperbenzoic acid (m-CPBA) as an oxidising reagent. Their ground-state and excited-state spectroscopic properties, singlet oxygen (¹O₂) production by the photodegradation of 1,3-diphenylisobenzofurane (DPBF) and theoretical lipophilicity were determined. In vitro analyses included cellular uptake, localisation and (photo)cytotoxicity under normoxia and CoCl₂-induced hypoxia. The CoCl₂ hypoxia model was used to reveal their properties, as related to HIF-1 activation and HIF-1α accumulation. (Oxido)pyridylporphyrins showed promising properties, such as the long lifetime of the excited triplet state, a high quantum yield of intersystem crossing, and high production of ROS/¹O₂. Lower cellular uptake resulted in an overall lower phototoxicity of these N-oxide porphyrins in comparison to their N-methylated analogues, and both porphyrin series were less active on CoCl₂-treated cells. (Oxido)pyridylporphyrins showed higher selectivity for pigmented melanoma cells, and the antioxidant activity of melanin pigment seemed to have a lower impact on their PDT activity compared to their N-methylated analogues in both CoCl₂-induced hypoxia and normoxia. Their potential HAP activity will be evaluated under conditions of reduced oxygen concentration in our future studies. Full article

Background/Objectives: Levocetirizine (LCZ) is a second-generation antihistamine with minimal central nervous system effects. However, its short half-life necessitates daily dosing, potentially reducing adherence in pediatric populations. This study aimed to develop a long-acting injectable LCZ formulation by synthesizing lipophilic prodrugs and evaluating their physicochemical stability, enzymatic hydrolysis, and pharmacokinetics in vivo. Methods: Two prodrugs of LCZ, LCZ decanoate (LCZ-D) and LCZ laurate (LCZ-L), were synthesized via esterification with alkyl alcohols. The compounds were characterized using NMR, FT-IR, and DSC. Prodrugs were formulated with an oil-based vehicle (castor oil and benzyl benozate), and their hydrolysis was evaluated using porcine liver esterase (PLE) and rat plasma. Pharmacokinetic profiles were assessed in Sprague Dawley rats after oral or intramuscular administration. Stability was tested at 25 °C, 40 °C, and 60 °C for 6 weeks. Results: LCZ-D and LCZ-L exhibited first-order hydrolysis kinetics, with rates following the order of PLE (2.0 > 0.5 units/mL) > plasma > PLE (0.2 units/mL). The C_max of LCZ-D and LCZ-L were 13.95 and 5.12 ng/mL, respectively, with corresponding AUC_0–45d values of 6423.12 and 2109.22 h·ng/mL. Formulations containing excipients with lower log P values led to increased systemic exposure. All formulations maintained therapeutic plasma concentrations for over 30 days. The inclusion of the antioxidant BHT (0.03% v/v) improved oxidative stability, reducing degradation at 60 °C from 4.72% to 1.17%. Conclusions: All formulations demonstrated potential for the long-acting delivery of LCZ, maintaining therapeutic plasma levels for over 30 days. Moreover, the release behavior and systemic exposure could be effectively modulated by excipient selection. Full article

Background/Objectives: Sustained drug exposure is a key factor in the treatment of patients infected with human immunodeficiency virus (HIV) or hepatitis B virus (HBV) in order to achieve the intended virological response. Although influenced also by other parameters, adherence to the treatment scheme is the most important for adequate drug exposure. This can be assessed by therapeutic drug monitoring (TDM). Tenofovir (TFV) is a nucleotide analogue used in the treatment of both HIV and HBV. Although various analytical methods for the quantification of tenofovir prodrugs have been published, there is limited literature on methods for simultaneous TFV and its active metabolite, tenofovir diphosphate (TFVDP) direct determination. Methods: In this study, we describe a novel micro-liquid-chromatography-mass spectrometry (micro-LC-MS/MS) method for TDM of TFV and TFVDP in biological matrices (whole blood, plasma). The challenging separation of the high-polarity analytes was resolved on an amino stationary phase, eluted in HILIC (hydrophilic interaction liquid chromatography) mode. The sample preparation included a clean-up step with hexane for the removal of lipophilic compounds and then protein precipitation with organic solvent. Results: The achieved low limits of quantification in blood were 0.25 ng/mL for TFV, and 0.5 ng/mL for TFVDP. Linearity, accuracy (91.63–109.18%), precision (2.48–14.08), and stability were validated for whole blood matrix, meeting the guidelines performance criteria. Samples collected from treated patients were analyzed, with results being in accordance with the reported pharmacokinetics. Conclusions: The new method is adequate for analyzing samples in a clinical set-up. The measurement of both TFV and TFVDP improves clinical decision by an in-depth evaluation of long-term adherence, and together with viral load and resistance data helps guiding the treatment towards the intended virological suppression. Full article

A Lipophilic Prodrug Charge Masking (LPCM) strategy involves masking of hydrophilic peptide charges with alkoxycarbonyl groups, which are cleaved by esterases after intestinal absorption. This study investigates the LPCM strategy’s applicability to oxytocin (OT), a peptide with well-defined biological activity. A series of OT prodrugs with varying alkoxycarbonyl chain lengths (2 to 12 carbon atoms) were synthesized, and their permeability was assessed using parallel artificial membrane permeability assay (PAMPA) and Caco-2 cell culture models. The PAMPA results indicated that OT demonstrated poor permeability (P_app = 2.2 × 10⁻⁶ cm/s), while its prodrugs Hoc-OT, Oct-OT, and Dec-OT were characterized by significantly better permeability, with Dec-OT achieving a four-fold increase over OT. The prodrug with a 12-carbon chain (Dod-OT) exhibited poor permeability; however, its high mass retention suggests strong membrane affinity. Further evaluation, using the Caco-2 cell model, revealed a 1.8-fold higher P_app of Oct-OT compared to OT, indicating possible higher oral availability. Conversely, Hoc-OT exhibited lower permeability than OT. Our findings indicate that the LPCM strategy can effectively boost the oral bioavailability of certain peptides, paving the way for their transformation into bioavailable drugs. Full article

Pronucleotides, after entering the cell, undergo chemical or enzymatic conversion into nucleotides with a free phosphate residue, and the released nucleoside 5′-monophosphate is then phosphorylated to the biologically active form, namely nucleoside 5′-triphosphate. The active form can inhibit HIV virus replication. For the most effective therapy, it is necessary to improve the transport of prodrugs into organelles. The introduction of new functional groups into their structure increases lipophilicity and, as a result, facilitates the interaction of pronucleotide molecules with components of biological membranes. Studies of these interactions were performed using the Langmuir technique. The prototype of the biological membrane was a thin monolayer composed of phospholipid molecules, DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine). The pronucleotides were 3′-azido-3′-deoxythymidine (AZT) analogs, formed by the phosphorylation of AZT to monophosphate (AZTMP) and containing various masking moieties that could increase their lipophilicity. Our results show the influence of the pronucleotide’s chemical structure on the fluidization of the model biomembrane. Changes in monolayer morphology in the presence of prodrugs were investigated by BAM microscopy. It was found that the incorporation of new groups into the structure of the drug as well as the concentration of AZT derivatives have a significant impact on the surface properties of the formed DPPC monolayer. Full article

Low oral bioavailability is a common feature in most drugs, including antibiotics, due to low solubility in physiological media and inadequate cell permeability, which may limit their efficacy or restrict their administration in a clinical setting. Cefuroxime is usually administered in its prodrug form, cefuroxime axetil. However, its preparation requires further reaction steps and additional metabolic pathways to be converted into its active form. The combination of Active Pharmaceutical Ingredients (APIs) with biocompatible organic molecules as salts is a viable and documented method to improve the solubility and permeability of a drug. Herein, the preparations of five organic salts of cefuroxime as an anion with enhanced physicochemical characteristics have been reported. These were prepared via buffer-assisted neutralization methodology with pyridinium and imidazolium cations in quantitative yields and presented as solids at room temperature. Cell viability studies on 3T3 cells showed that only the cefuroxime salts combined with longer alkyl chain cations possess higher cytotoxicity than the original drug, and while most salts lost in vitro antibacterial activity against E. coli, P. aeruginosa and B. subtilis, one compound, [PyC₁₀Py][CFX]₂, retained the activity. Cefuroxime organic salts have a water solubility 8-to-200-times greater than the original drug at 37 °C. The most soluble compounds have a very low octanol-water partition, similar to cefuroxime, while more lipophilic salts partition predominantly to the organic phase. Full article

A series of 61 thiazolidine-2,4-diones bearing a styryl group at position 5 was synthesized in 2–5 steps and their structure was proved by elemental and spectral analyses. The compounds obtained were evaluated in vitro against the promastigote stage of the kinetoplastid parasite Leishmania infantum and the human HepG2 cell line, to determine selectivity indices and to compare their activities with those of antileishmanial reference drugs. The study of structure–activity relationships indicated the potential of some derivatives bearing a nitro group on the phenyl ring, especially when located at the meta position. Thus, among the tested series, compound 14c appeared as a hit compound with good antileishmanial activity (EC₅₀ = 7 µM) and low cytotoxicity against both the hepatic HepG2 and macrophage THP-1 human cell lines (CC₅₀ = 101 and 121 µM, respectively), leading to good selectivity indices (respectively, 14 and 17), in comparison with the reference antileishmanial drug compound miltefosine (EC₅₀ = 3.3 µM, CC₅₀ = 85 and 30 µM, SI = 26 and 9). Regarding its mechanism of action, among several possibilities, it was demonstrated that compound 14c is a prodrug bioactivated, predominantly by L. donovani nitroreductase 1, likely leading to the formation of cytotoxic metabolites that form covalent adducts in the parasite. Finally, compound 14c is lipophilic (measured CHI LogD_7.7 = 2.85) but remains soluble in water (measured PBS solubility at pH_7.4 = 16 µM), highlighting the antileishmanial potential of the nitrostyrylthiazolidine-2,4-dione scaffold. Full article

E. coli nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO₂). In this work, we determined the standard redox potential of FMN of NfsA to be −215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO₂ and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO₂ increases with their electron affinity (single-electron reduction potential, E¹₇) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on E¹₇, but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π–π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO₂ reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents. Full article

NDH-4338 is a highly lipophilic prodrug comprising indomethacin and an acetylcholinesterase inhibitor. A design of experiments approach was used to synthesize, characterize, and evaluate the wound healing efficacy of optimized NDH-4338 nanosuspensions against nitrogen mustard-induced skin injury. Nanosuspensions were prepared by sonoprecipitation in the presence of a Vitamin E TPGS aqueous stabilizer solution. Critical processing parameters and material attributes were optimized to reduce particle size and determine the effect on dissolution rate and burn healing efficacy. The antisolvent/solvent ratio (A/S), dose concentration (DC), and drug/stabilizer ratio (D/S) were the critical sonoprecipitation factors that control particle size. These factors were subjected to a Box–Behnken design and response surface analysis, and model quality was assessed. Maximize desirability and simulation experiment optimization approaches were used to determine nanosuspension parameters with the smallest size and the lowest defect rate within the 10–50 nm specification limits. Optimized and unoptimized nanosuspensions were prepared and characterized. An established depilatory double-disc mouse model was used to evaluate the healing of nitrogen mustard-induced dermal injuries. Optimized nanosuspensions (A/S = 6.2, DC = 2% w/v, D/S = 2.8) achieved a particle size of 31.46 nm with a narrow size range (PDI = 0.110) and a reduced defect rate (42.2 to 6.1%). The optimized nanosuspensions were stable and re-dispersible, and they showed a ~45% increase in cumulative drug release and significant edema reduction in mice. Optimized NDH-4338 nanosuspensions were smaller with more uniform sizes that led to improved physical stability, faster dissolution, and enhanced burn healing efficacy compared to unoptimized nanosuspensions. Full article

Arginine, due to the guanidine moiety, increases peptides’ hydrophilicity and enables interactions with charged molecules, but at the same time, its presence in a peptide chain might reduce its permeability through biological membranes. This might be resolved by temporary coverage of the peptide charge by lipophilic, enzyme-sensitive alkoxycarbonyl groups. Unfortunately, such a modification of a guanidine moiety has not been reported to date and turned out to be challenging. Here, we present a new, optimized strategy to obtain arginine building blocks with increased lipophilicity that were successfully utilized in the solid-phase peptide synthesis of novel arginine vasopressin prodrugs. Full article

SARS-CoV-2 is a highly contagious and pathogenic virus that first appeared in late December 2019 and caused a global pandemic in a short period. The virus is a single-stranded RNA virus belonging to the Coronaviridae family. Numerous treatments have been developed and tested in response to the pandemic, particularly antiviral drugs. Among them, GS441524 (GS441), a nucleoside antiviral drug, has demonstrated promising results in inhibiting SARS-CoV-2. Nevertheless, the limited oral bioavailability of GS441 restricts its application to patients with the virus. In this study, a novel prodrug of GS441 (NGP-1) with an isobutyl ester and cyclic carbonate structure was designed and synthesized. Its purity and the stability in different artificial digestive juices of NGP-1 was determined with HPLC-DAD methods. The pharmacokinetics of NGP-1 and GS441 were studied in rats via gavage administration. A new LC-MS/MS method was developed to quantitatively analyze GS441 in plasma samples. The results showed that the k_a, C_max, and MRT of converted GS441 from NGP-1 were 5.9, 3, and 2.5 times greater than those of GS441 alone. The F_rel of NGP-1 was approximately four-fold that of GS441, with an AUC_0–∞ of 9716.3 h·ng mL⁻¹. As a prodrug of GS441, NGP-1 increased its lipophilicity, absorption, and bioavailability, indicating that it holds promise in improving the clinical efficacy of anti-SARS-CoV-2 medications. Full article

Formulating low-solubility or low-permeability drugs is a challenge, particularly with the low administration volumes required in intranasal drug delivery. Nanoemulsions (NE) can solve both issues, but their production and physical stability can be challenging, particularly when a high proportion of lipids is necessary. Hence, the aim of the present work was to develop a NE with good solubilization capacity for lipophilic drugs like simvastatin and able to promote the absorption of drugs with low permeability like fosphenytoin. Compositions with high proportion of two lipids were screened and characterized. Surprisingly, one of the compositions did not require high energy methods for high droplet size homogeneity. To better understand formulation factors important for this feature, several related compositions were evaluated, and their relative cytotoxicity was screened. Optimized compositions contained a high proportion of propylene glycol monocaprylate NF, formed very homogenous NE using a low-energy phase inversion method, solubilized simvastatin at high drug strength, and promoted a faster intranasal absorption of the hydrophilic prodrug fosphenytoin. Hence, a new highly homogeneous NE obtained by a simple low-energy method was successfully developed, which is a potential alternative for industrial application for the solubilization and protection of lipophilic actives, as well as (co-)administration of hydrophilic molecules. Full article

Previously, we showed in the human umbilical vein endothelial cells (HUVECs) model that a liposome formulation of melphalan lipophilic prodrug (MlphDG) decorated with selectin ligand tetrasaccharide Sialyl Lewis X (SiaLe^X) undergoes specific uptake by activated cells and in an in vivo tumor model causes a severe antivascular effect. Here, we cultured HUVECs in a microfluidic chip and then applied the liposome formulations to study their interactions with the cells in situ under hydrodynamic conditions close to capillary blood flow using confocal fluorescent microscopy. The incorporation of 5 to 10% SiaLe^X conjugate in the bilayer of MlphDG liposomes increased their consumption exclusively by activated endotheliocytes. The increase of serum concentration from 20 to 100% in the flow resulted in lower liposome uptake by the cells. To elucidate the possible roles of plasma proteins in the liposome–cell interactions, liposome protein coronas were isolated and analyzed by shotgun proteomics and immunoblotting of selected proteins. Proteomic analysis showed that a gradual increase in SiaLe^X content correlated with the overall enrichment of the liposome-associated proteins with several apolipoproteins, including the most positively charged one, ApoC1, and serum amyloid A4, associated with inflammation, on the one hand, and a decrease in the content of bound immunoglobulins, on the other. The article discusses the potential interference of the proteins in the binding of liposomes to selectins of endothelial cells. Full article