Solubility Determination of Active Pharmaceutical Ingredients Which Have Been Recently Added to the List of Essential Medicines in the Context of the Biopharmaceutics Classification System-Biowaiver

Quality testing of mifepristone and misoprostol in 11 countries

OBJECTIVE

Previous studies have demonstrated quality concerns with misoprostol. Mifepristone, however, has not been extensively assessed for quality. Between 2020 and 2021, Concept Foundation and the International Planned Parenthood Federation conducted a study to determine the quality of these medical abortion drugs in low- and middle-income countries (LMIC).

METHODS

The collection of batch samples of misoprostol and mifepristone was carried out by trained sampling agents in selected LMIC. Single drug packs and combipacks were sampled. A World Health Organization prequalified laboratory conducted testing method verifications and subsequent sample analysis. Tests included identification, assay, related substances, and content uniformity for misoprostol, and identification, assay, related substances, and dissolution for mifepristone.

RESULTS

Samples were collected from Burkina Faso, Cambodia, Democratic Republic of Congo, India, Kyrgyzstan, Moldova, Nepal, Nigeria, Pakistan, Uganda and Vietnam. Sixty-four pooled batch samples were tested, consisting of 31 combipacks, 26 misoprostol-only and seven mifepristone-only products. Overall, 54.7% of samples were non-compliant with one or more of the specifications, representing 51.6% of combipack products, 57.1% of misoprostol tablets analyzed and 23.7% of mifepristone tablets. One falsified misoprostol-only product was found.

CONCLUSION

The present study confirms that a significant problem still exists in relation to the quality of medical abortion drugs in LMIC. For misoprostol, our findings suggest that historical concerns around primary packaging may have been largely resolved but that manufacturing processes for both finished product and active pharmaceutical ingredient need to be improved. The present study also provides evidence of mifepristone quality issues.

Oseltamivir phosphate interaction with model membranes

Oseltamivir belongs to the neuraminidase inhibitors, developed against the influenza virus, and registered under the trademark Tamiflu. Despite its long-term acquaintance, there is limited information in the literature about its physicochemical and structural properties in a lipid-water system. We present an experimentally determined partition coefficient with structural information on the interaction of oseltamivir with the model membrane, its possible location, and its effect on the membrane thermodynamics. The hydrophobic part of the lipid bilayer is affected to a moderate extent, which was proved by slight changes in thermal and structural properties. Hereby, interaction of oseltamivir with the phospholipid bilayer induces concentration dependent decrease of lateral pressure in the bilayer acyl chain region. Oseltamivir charges the bilayer surface positively, which results in the zeta potential increase and changes in anisotropic properties studied by the polarised light microscopy. At the highest oseltamivir concentrations studied, the multilamellar structure is extensively disturbed, likely due to electrostatic repulsion between the adjacent bilayers.

Medication use in a cohort of adults with chronic intestinal failure: A prospective cross-sectional study

BACKGROUND

Oral drug therapy may be compromised in chronic intestinal failure (IF) because of alterations in absorption and transit. Only scarce literature is available on which medication patients with chronic IF take in daily life. The aim was to describe the medication use in these patients.

METHODS

A medication history was obtained from adults with chronic IF treated in our tertiary care IF center. Degree of polypharmacy, drug classes, Biopharmaceutics Classification System classes, route of administration, and formulation of drugs were analyzed.

RESULTS

From October 2019 until December 2020, 72 patients (35 patients with short bowel syndrome [SBS] and 37 patients without SBS) were included. Polypharmacy was seen in 85.7% of patients with SBS and 75.7% of patients without SBS. The top three drug classes were proton-pump inhibitors, vitamin D or acetaminophen, and antimotility medication or laxatives/benzodiazepines. Approximately 25% of the drugs were classified as Biopharmaceutics Classification System class I drugs. In patients with SBS (78%) and patients without SBS (74.9%), most medication was taken orally, requiring gastrointestinal absorption of the active substance to be pharmacologically active. Most of these medications (77% in patients with SBS and 80.8% in patients without SBS) were formulated as a capsule or tablet, requiring disintegration and dissolution in the gastrointestinal tract before absorption can take place.

CONCLUSION

Polypharmacy was observed in most patients with chronic IF. Most medication was taken orally in formulations requiring disintegration, dissolution, and gastrointestinal absorption, which could be compromised in chronic IF.

Towards Effective Antiviral Oral Therapy: Development of a Novel Self-Double Emulsifying Drug Delivery System for Improved Zanamivir Intestinal Permeability

Self-double emulsifying drug delivery systems have the potential to enhance the intestinal permeability of drugs classified under the Biopharmaceutics Classification System (BCS) class III. One such example is the antiviral agent zanamivir, exhibiting suboptimal oral absorption (with a bioavailability range of 1-5%). To address this challenge, we have developed an innovative oral formulation for zanamivir: a self-double nanoemulsifying Winsor delivery system (SDNE-WDS) consisting of the microemulsion, which subsequently yields final double nanoemulsion (W1/O/W2) upon interaction with water. Two distinct formulations were prepared: SDNE-WDS1, classified as a W/O microemulsion, and SDNE-WDS2, discovered to be a bicontinuous microemulsion. The inner microemulsions displayed a consistent radius of gyration, with an average size of 35.1 ± 2.1 nm. Following self-emulsification, the resultant zanamivir-loaded nanoemulsion droplets for zSDNE-WDS1 and zSDNE-WDS2 measured 542.1 ± 36.1 and 174.4 ± 3.4 nm, respectively. Both types of emulsions demonstrated the ability to enhance the transport of zanamivir across a parallel artificial membrane. Additionally, in situ rat intestinal perfusion studies involving drug-loaded SDNE-WDSs revealed a significantly increased permeability of zanamivir through the small intestinal wall. Notably, both SDNE-WDS formulations exhibited effective permeability (Peff) values that were 3.5-5.5-fold higher than those of the low/high permeability boundary marker metoprolol. This research emphasizes the success of SDNE-WDSs in overcoming intestinal permeability barriers and enabling the effective oral administration of zanamivir. These findings hold promise for advancing the development of efficacious oral administration of BCS class III drugs.

C2-linked alkynyl poly-ethylene glycol(PEG) adenosine conjugates as water-soluble adenosine receptor agonists

A series of 12 novel polyethylene-glycol(PEG)-alkynyl C2-adenosine(ADN) conjugates were synthesized using a robust Sonogashira coupling protocol and characterized by NMR spectroscopy and mass spectrometry analysis. The ADN-PEG conjugates showed null to moderate toxicity in murine macrophages and 12c was active against Mycobacterium aurum growth (MIC = 62.5 mg/L). The conjugates were not active against Mycobacterium bovis BCG. Conjugates 10b and 11b exhibited high water solubility with solubility values of 1.22 and 1.18 mg/ml, respectively, in phosphate buffer solutions at pH 6.8. Further, 10b and 11b induced a significant increase in cAMP accumulation in RAW264.7 cells comparable with that induced by adenosine. Analogues 10c, 11c and 12c were docked to the A₁ , A_2A , A_2B and A₃ adenosine receptors (ARs) using crystal-structures and homology models. ADN-PEG-conjugates bearing chains with up to five ethyleneoxy units could be well accommodated within the binding sites of A₁ , A_2A and A₃ ARs. Docking studies showed that compound 10b and 11b were the best A_2A receptor binders of the series, whereas 12c was the best binder for A₁ AR. In summary, introduction of hydrophilic PEG substituents at the C2 of adenine ring significantly improved water solubility and did not affect AR binding properties of the ADN-PEG conjugates.

An overview on liquisolid technique: its development and applications

With its simplicity and cost-effectiveness, the liquisolid technique offers solutions for numerous formulation problems. Among these are dissolution enhancement and sustaining drug release, and the liquisolid technique dealt with both approaches. This review focuses on the latest advances in the technique. It discusses modified additives for use as carrier materials, which secure the required large surface area for enclosing liquids. The review also covers the modern liquipellet technique derived from the extrusion/palletization technique. Also, the liquiground term is introduced, combining the advantages of co-grinding with the liquisolid concept. Furthermore, several grades of Eudragits, and hydrophilic retarding polymers are mentioned to explain modes of sustaining drug release. This review sums up the liquisolid technique development and its applications recently achieved.

Successful Dendrimer and Liposome-Based Strategies to Solubilize an Antiproliferative Pyrazole Otherwise Not Clinically Applicable

Water-soluble formulations of the pyrazole derivative 3-(4-chlorophenyl)-5-(4-nitrophenylamino)-1H-pyrazole-4-carbonitrile (CR232), which were proven to have in vitro antiproliferative effects on different cancer cell lines, were prepared by two diverse nanotechnological approaches. Importantly, without using harmful organic solvents or additives potentially toxic to humans, CR232 was firstly entrapped in a biodegradable fifth-generation dendrimer containing lysine (G5K). CR232-G5K nanoparticles (CR232-G5K NPs) were obtained with high loading (DL%) and encapsulation efficiency (EE%), which showed a complex but quantitative release profile governed by Weibull kinetics. Secondly, starting from hydrogenated soy phosphatidylcholine and cholesterol, we prepared biocompatible CR232-loaded liposomes (CR232-SUVs), which displayed DL% and EE% values increasing with the increase in the lipids/CR232 ratio initially adopted and showed a constant prolonged release profile ruled by zero-order kinetics. When relevant, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS) experiments, as well as potentiometric titrations completed the characterization of the prepared NPs. CR232-G5K NPs were 2311-fold more water-soluble than the pristine CR232, and the CR232-SUVs with the highest DL% were 1764-fold more soluble than the untreated CR232, thus establishing the success of both our strategies.

The Development and the Validation of a Novel Dissolution Method of Favipiravir Film-Coated Tablets

The aim of this study was to develop and validate a dissolution test for favipiravir release in a tablet dosage form using ultra-high performance liquid chromatography (UHPLC). The dissolution method was developed by testing the solubility of favipiravir in media with different pH values. The results demonstrated that the best dissolution was achieved in phosphate buffer with a pH of 6.8. The amount of favipiravir that was released was about 100% after 30 min. The UHPLC method presented linearity (R = 1.000) in the concentration range of 0.044–0.44 mg/mL. The recovery parameter that was achieved ranged from 102.5% to 104.2%. The system suitability, repeatability, and intermediate precision RSD% results were found to be 0.36%, 1.99%, and 2.49%, respectively. In addition to these parameters and results, an F-test was performed using the Minitab 18 Statistical Software program for the intermediate precision and repeatability results. The standard and sample solutions were found to be stable for 2 days in their respective dissolution medium. This analytical method was also found to be selective for favipiravir. In conclusion, a simple and feasible dissolution method with a short run time of 2.5 min was developed and validated successfully. The obtained results demonstrated that the dissolution test developed here is adequate for its purpose and can be applied as the dissolution method for favipiravir in film-coated tablets for release analyses.

Eplerenone nanocrystals engineered by controlled crystallization for enhanced oral bioavailability

Poor aqueous solubility of eplerenone (EPL) is a major obstacle to achieve sufficient bioavailability after oral administration. In this study, we aimed to develop and evaluate eplerenone nanocrystals (EPL-NCs) for solubility and dissolution enhancement. D-optimal combined mixture process using Design-Expert software was employed to generate different combinations for optimization. EPL-NCs were prepared by a bottom-up, controlled crystallization technique during freeze-drying. The optimized EPL-NCs were evaluated for their size, morphology, thermal behavior, crystalline structure, saturation solubility, dissolution profile, in vivo pharmacokinetics, and acute toxicity. The optimized EPL-NCs showed mean particle size of 46.8 nm. Scanning electron microscopy revealed the formation of elongated parallelepiped shaped NCs. DSC and PXRD analysis confirmed the crystalline structure and the absence of any polymorphic transition in EPL-NCs. Furthermore, EPL-NCs demonstrated a 17-fold prompt increase in the saturation solubility of EPL (8.96 vs. 155.85 µg/mL). The dissolution rate was also significantly higher as indicated by ∼95% dissolution from EPL-NCs in 10 min compared to only 29% from EPL powder. EPL-NCs improved the oral bioavailability as indicated by higher AUC, C_max, and lower T_max than EPL powder. Acute oral toxicity study showed that EPL-NCs do not pose any toxicity concern to the blood and vital organs. Consequently, NCs prepared by controlled crystallization technique present a promising strategy to improve solubility profile, dissolution velocity and bioavailability of poorly water-soluble drugs.

Preparation and Physicochemical Characterization of Water-Soluble Pyrazole-Based Nanoparticles by Dendrimer Encapsulation of an Insoluble Bioactive Pyrazole Derivative

2-(4-Bromo-3,5-diphenyl-pyrazol-1-yl)-ethanol (BBB4) was synthetized and successfully evaluated concerning numerous biological activities, except for antimicrobial and cytotoxic effects. Due to the antimicrobial effects possessed by pyrazole nucleus, which have been widely reported, and the worldwide need for new antimicrobial agents, we thought it would be interesting to test BBB4 and to evaluate its possible antibacterial effects. Nevertheless, since it is water-insoluble, the future clinical application of BBB4 will remain utopic unless water-soluble BBB4 formulations are developed. To this end, before implementing biological evaluations, BBB4 was herein re-synthetized and characterized, and a new water-soluble BBB4-based nano-formulation was developed by its physical entrapment in a biodegradable non-cytotoxic cationic dendrimer (G4K), without recovering harmful solvents as DMSO or surfactants. The obtained BBB4 nanoparticles (BBB4-G4K NPs) showed good drug loading (DL%), satisfying encapsulation efficiency (EE%), and a biphasic quantitative release profile governed by first-order kinetics after 24 h. Additionally, BBB4-G4K was characterized by ATR-FTIR spectroscopy, NMR, SEM, dynamic light scattering analysis (DLS), and potentiometric titration experiments. While, before the nanotechnological manipulation, BBB4 was completely water-insoluble, in the form of BBB4-G4K NPs, its water-solubility resulted in being 105-fold higher than that of the pristine form, thus establishing the feasibility of its clinical application.

Foams as unique drug delivery systems

Foams are multiphase systems found throughout nature. We meet them equally often in our everyday life, starting with the foam in the morning espresso, where the foam should constitute 10% of the drink or in a glass of beer and ending with the evening bath with foam. These multiphase systems consist mainly of gas, which is separated by liquid or solid lamellae. The lamellae have a very large surface area and a small thickness, which results in their low stability. The foams in pharmaceutics are known for a long time as protective or therapeutic preparations for topical use. However, the physicochemical structure of both solid and liquid foams offers multiple fields of application in the modern therapy. For instance, owing to the unique structure, foams can be also used for parenteral use in the form of implants serving as a drug carrier and at the same time, a scaffold for regenerating the tissue. Foams can also be used orally in the form of controlled drug delivery systems that are potentially useful for sustained or targeted drug delivery. The article describes the unique advantages and features of foams that make them useful in modern pharmacotherapy.

Impact of simulated lung fluid components on the solubility of inhaled drugs and predicted in vivo performance

Orally inhaled products (OIPs) are gaining increased attention, as pulmonary delivery is a preferred route for the treatment of various diseases. Yet, the field of inhalation biopharmaceutics is still in development phase. For a successful correlation between various in vitro data obtained during formulation characterization and in vivo performance, it is necessary to understand the impact of parameters such as solubility and dissolution of drugs. In this work, we used in vitro-in silico feedback-feedforward approach to gain a better insight into the biopharmaceutics behavior of inhaled Salbutamol Sulphate (SS) and Budesonide (BUD). The thorough characterization of the in vitro test media and the impact of different in vitro fluid components such as lipids and protein on the solubility of aforementioned drugs was studied. These results were subsequently used as an input into the developed in silico models to investigate potential PK parameter changes in vivo. Results revealed that media comprising lipids and albumin were the most biorelevant and impacted the solubility of BUD the most. On the contrary, no notable impact was seen in case of SS. The use of simple media such as phosphate buffer saline (PBS) might be sufficient to use in solubility studies of the highly soluble and permeable drugs. However, its use for the poorly soluble drugs is limited due to the greater potential for interactions within in vivo environment. The use of in silico tools showed that the model response varies, depending on the used media. Therefore, this work highlights the relevance of carefully selecting the media composition when investigating solubility and dissolution behavior, especially in the early phases of drug development and of poorly soluble drugs.

Crucial Role of PLGA Nanoparticles in Mitigating the Amiodarone-Induced Pulmonary Toxicity

BACKGROUND

Amiodarone (AMD) is a widely used anti-arrhythmic drug, but its administration could be associated with varying degrees of pulmonary toxicity. In attempting to circumvent this issue, AMD-loaded polymeric nanoparticles (AMD-loaded NPs) had been designed.

MATERIALS AND METHODS

AMD was loaded in NPs by the nanoprecipitation method using two stabilizers: bovine serum albumin and Kolliphor® P 188. The physicochemical properties of the AMD-loaded NPs were determined. Among the prepared NPs, two ones were selected for further investigation of spectral and thermal analysis as well as morphological properties. Additionally, in vitro release patterns were studied and kinetically analyzed at different pH values. In vitro cytotoxicity of an optimized formula (NP4) was quantified using A549 and Hep-2 cell lines. In vivo assessment of the pulmonary toxicity on Sprague Dawley rats via histopathological and immunohistochemical evaluations was applied.

RESULTS

The developed NPs achieved a size not more than 190 nm with an encapsulation efficiency of more than 88%. Satisfactory values of loading capacity and yield were also attained. The spectral and thermal analysis demonstrated homogeneous entrapment of AMD inside the polymeric matrix of NPs. Morphology revealed uniform, core-shell structured, and sphere-shaped particles with a smooth surface. Furthermore, the AMD-loaded NPs exhibited a pH-dependent and diffusion-controlled release over a significant period without an initial burst effect. NP4 demonstrated a superior cytoprotective efficiency by diminishing cell death and significantly increasing the IC50 by more than threefold above the pure AMD. Also, NP4 ameliorated AMD-induced pulmonary damage in rats. Significant downregulation of inflammatory mediators and free radicle production were noticed in the NP4-treated rats.

CONCLUSION

The AMD-loaded NPs could ameliorate the pulmonary injury induced by the pure drug moieties. Cytoprotective, anti-fibrotic, anti-inflammatory, and antioxidant properties were presented by the optimized NPs (NP4). Future studies may be built on these findings for diminishing AMD-induced off-target toxicities.

Foldable/Expandable Gastro-retentive Films Based on Starch and Chitosan as a Carrier For Prolonged Release of Resveratrol

BACKGROUND

Resveratrol exerts a number of therapeutic effects, notably anti-inflammatory, antioxidant and anti-cancer activities which are beneficial for the treatment of gastric diseases. However, the efficacy of resveratrol is severely limited due to the poor aqueous solubility and rapid metabolism following oral administration. As a result, foldable/expandable devices based on natural polymers merging with solid dispersion technology have been developed to increase the solubility, prolong the gastric residence time, and provide a controlled release therapy of resveratrol.

OBJECTIVES

This research aimed to invent foldable/expandable films based on natural polymers, including starch and chitosan, for stomach-specific delivery and prolonged release of resveratrol.

METHODS

The films were prepared by solvent casting using either rice, tapioca, corn starch or pre-gelatinized corn starch combined with chitosan in different weight to weight ratios. Glycerol was included as a plasticizer. Resveratrol solid dispersions (Res-SD) prepared by solvent evaporation and employing PVP-K30 as a hydrophilic polymer were loaded into the polymeric film, which was subsequently folded prior to insertion in a hard gelatin capsule.

RESULTS

The solid dispersions improved the solubility of resveratrol by a factor of 500. All Res-SD loaded film formulations completely unfolded in simulated gastric fluid at 37oC within 10 min. Fluid absorption by the films was influenced by the ratio of amylose and amylopectin in the starch granules, with tapioca starch formulations displaying the highest fluid uptake. Films prepared from pre-gelatinized corn starch and chitosan resulted in highly efficient delivery of resveratrol, with more than 80%of the content released over a period of 12 hrs. Furthermore, the released polyphenol exhibited cytotoxic activity against human gastric adenocarcinoma cells and anti-inflammatory effects against lipopolysaccharide-stimulated murine, macrophage-like cells.

CONCLUSIONS

These findings demonstrate the potential of foldable/expandable films based on natural polymers as a promising stomach-specific carrier for improving the treatment of gastric disorders.

Population pharmacokinetic modeling of intramuscular and oral dexamethasone and betamethasone in Indian women

Population analysis of pharmacokinetic data for five differing dosage forms and routes for dexamethasone and betamethasone in 48 healthy nonpregnant Indian women was performed that accounted for a partial and complex cross-over design. Single doses of 6 mg dexamethasone phosphate (DEX-P), betamethasone phosphate (BET-P), or 1:1 mixture of betamethasone phosphate and acetate (BET-PA) were administered orally (PO) or intramuscularly (IM). Plasma concentrations collected for two periods over 96 h were described with a two-compartment model with differing PO and IM first-order absorption inputs. Clearances and volumes were divided by the IM bioavailability [Formula: see text]. The homogeneous ages, body weights, and ethnicity of the women obviated covariate analysis. Parameter estimates were obtained by the Laplace estimation method implemented in NONMEM 7.4. Typical values for dexamethasone were clearance ([Formula: see text] of 9.29 L/h, steady-state volume ([Formula: see text] of 56.4 L, IM absorption constant [Formula: see text] of 0.460 1/h and oral absorption constant ([Formula: see text] of 0.936 1/h. Betamethasone parameters were CL/FIM of 5.95 L/h, [Formula: see text] of 72.4 L, [Formula: see text] of 0.971 1/h, and [Formula: see text] of 1.21 1/h. The PO to IM F values were close to 1.0 for both drugs. The terminal half-lives averaged about 7.5 h for DEX, 17 h for BET, and 78 h for BET from BET-PA with the latter reflecting very slow release of BET from the acetate ester. Overall, BET exhibited slower clearance, larger volume of distribution, faster absorption, and longer persistence than DEX. These data may be useful in considering exposures when substituting one form of corticosteroid for another.

New liquid oral formulations of hydroxychloroquine: a physicochemical stability study

Objectives

Hydroxychloroquine (HCQ) presents many drug properties that increase its therapeutic use. There are, indeed, different research pathways in numerous autoimmune, inflammatory, and infectious diseases, as well as in cancerology. HCQ is only marketed as HCQ sulfate in film-coated or coated tablets for oral use. No pediatric liquid form is currently available on the market. The purpose of the present study is to develop oral liquid formulations for HCQ at 50 mg/mL with two different oral vehicle suspensions, namely ORA-Plus®/ORA-Sweet® (ORA) and Syrspend® SF PH 4 (SYR).

Methods

The suspension stability was assessed in different storage conditions (4 and 25 °C). A high-pressure liquid chromatography (HPLC) stability-indicating method with UV detection was developed to determine HCQ concentrations in the different formulations, and detect potential degradation products. Physical parameters, e.g. pH and osmolality were also monitored during the period of the stability study.

Results

HCQ concentration, osmolality, and pH remained stable for 90 days at 4 and 30 °C for HCQ in 50% ORA-Plus®/50% ORA-Sweet®. For HCQ suspension in SYR, the suspension remained stable 90 days at 4 °C and 60 days at 30 °C.

Conclusions

For all preparations, no significant physical or chemical modification was noticed during the period of the study.

An in-depth analysis of novel combinatorial drug therapy via nanocarriers against HIV/AIDS infection and their clinical perspectives: a systematic review

Introduction: Conventional antiretroviral therapy against HIV infections is threatening to become outdated due to the low chemical, physical, biological, and pharmacokinetic characteristics of therapeutic molecules, followed by the high chance of emergence of drug resistance. Considering the co-encapsulation of multi-infection agents in a single nanocarrier is emerging to offer various benefits such as synergistic action, improved therapeutic efficacy, reduced drug resistance development, patient compliance, and economical therapy.Areas covered: A systematic review of nano-based combinatorial drug therapy was performed using various databases including Scopus, PubMed, Google Scholar, and Science Direct between 2000 and 2020. The search set was screened as per the inclusion and exclusion criteria, followed by 46 scientific articles and seven clinical studies selected for in-depth analysis.Expert opinion: There has been an immense effort to analyze the mechanism of HIV infection to develop a promising therapeutic approach, although the aim of complete prevention has not been succeeded yet. The key finding is to overcome the challenges associated with conventional therapy by the combinatorial drug in a single nanoformulation, which holds great potential for impact in the management of HIV infection.

Solubility Data, Solubility Parameters and Thermodynamic Behavior of an Antiviral Drug Emtricitabine in Different Pure Solvents: Molecular Understanding of Solubility and Dissolution

The solubility values, various Hansen solubility parameters (HSPs) and thermodynamic behavior of emtricitabine (ECT) in twelve different pure solvents (PS) were estimated using various experimental as well as computational methods. Experimental solubility values (x_e) of ECT in twelve different PS were obtained at T = 298.2 K to 318.2 K and p = 0.1 MPa. The x_e values of ECT were correlated by “van’t Hoff, Apelblat and Buchowski-Ksiazaczak λh models”. Various HSPs for ECT and twelve different PS were also calculated using “HSPiP software”. The x_e values of ECT were estimated maximum in polyethylene glycol-400 (PEG-400; 1.41 × 10⁻¹), followed by ethylene glycol, Transcutol-HP, propylene glycol, methanol, water, isopropanol, ethanol, 1-butanol, dimethyl sulfoxide, 2-butanol and EA (1.28 × 10⁻³) at T = 318.2 K. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of ECT. Overall, PEG-400 was found as the best/ideal solvent for solubility/miscibility of ECT compared to other solvents studied.

Quantitative Analysis of Emtricitabine in Dosage Forms Using Green RP-HPTLC and Routine NP-HPTLC Methods-A Contrast of Validation Parameters

In this research, an antiviral drug emtricitabine (ECT) was quantified using the validated green reversed-phase high-performance thin-layer chromatography (RP-HPTLC) and routine normal-phase HPTLC (NP-HPTLC) methods in the marketed oral solutions and capsules. Green RP-HPTLC-densitometry quantification was performed using the acetone/water (70:30, v/v) solvent system as the mobile phase. Routine NP-HPTLC-densitometry quantification was performed using the chloroform/methanol (85:15, v/v) solvent system as the mobile phase. The detection was performed at λmax-285 nm for both of the methods. Both densitometry methods were validated for different parameters. Most of the validation parameters including linearity, precision, accuracy, detection, and quantification limits for the green densitometry method were found to be superior compared to the routine densitometry technique. The ECT contents of commercial oral solution and commercial capsules were found to be 100.85 and 98.27%, respectively, using the green densitometry technique. The ECT contents of oral solutions and capsules were 97.16 and 95.54%, respectively, using the routine densitometry technique. Accordingly, the green densitometry technique was found to be better than the routine densitometry technique for ECT assays. Thus, the green densitometry technique can be successfully applied for the quantitation of ECT in the marketed formulations.

Biomimetic Artificial Membrane Permeability Assay over Franz Cell Apparatus Using BCS Model Drugs

A major parameter controlling the extent and rate of oral drug absorption is permeability through the lipid bilayer of intestinal epithelial cells. Here, a biomimetic artificial membrane permeability assay (Franz-PAMPA Pampa) was validated using a Franz cells apparatus. Both high and low permeability drugs (metoprolol and mannitol, respectively) were used as external standards. Biomimetic properties of Franz-PAMPA were also characterized by electron paramagnetic resonance spectroscopy (EPR). Moreover, the permeation profile for eight Biopharmaceutic Classification System (BCS) model drugs cited in the FDA guidance and another six drugs (acyclovir, cimetidine, diclofenac, ibuprofen, piroxicam, and trimethoprim) were measured across Franz-PAMPA. Apparent permeability (Papp) Franz-PAMPA values were correlated with fraction of dose absorbed in humans (Fa%) from the literature. Papp in Caco-2 cells and Corti artificial membrane were likewise compared to Fa% to assess Franz-PAMPA performance. Mannitol and metoprolol Papp values across Franz-PAMPA were lower (3.20 × 10^-7 and 1.61 × 10^-5 cm/s, respectively) than those obtained across non-impregnated membrane (2.27 × 10^-5 and 2.55 × 10^-5 cm/s, respectively), confirming lipidic barrier resistivity. Performance of the Franz cell permeation apparatus using an artificial membrane showed acceptable log-linear correlation (R² = 0.664) with Fa%, as seen for Papp in Caco-2 cells (R² = 0.805). Data support the validation of the Franz-PAMPA method for use during the drug discovery process.

"Flexible-Acceptor" General Solubility Equation for beyond Rule of 5 Drugs

This study describes a novel nonlinear variant of the well-known Yalkowsky general solubility equation (GSE). The modified equation can be trained with small molecules, mostly from the Lipinski Rule of 5 (Ro5) chemical space, to predict the intrinsic aqueous solubility, S₀, of large molecules (MW > 800 Da) from beyond the rule of 5 (bRo5) space, to an accuracy almost equal to that of a recently described random forest regression (RFR) machine learning analysis. The new approach replaces the GSE constant factors in the intercept (0.5), the octanol-water log P (-1.0), and melting point, mp (-0.01) terms with simple exponential functions incorporating the sum descriptor, Φ+B (Kier Φ molecular flexibility and Abraham H-bond acceptor potential). The constants in the modified three-variable (log P, mp, Φ+B) equation were determined by partial least-squares (PLS) refinement using a small-molecule log S₀ training set (n = 6541) of mostly druglike molecules. In this "flexible-acceptor" GSE(Φ,B) model, the coefficient of log P (normally fixed at -1.0) varies smoothly from -1.1 for rigid nonionizable molecules (Φ+B = 0) to -0.39 for typically flexible (Φ ∼ 20, B ∼ 6) large molecules. The intercept (traditionally fixed at +0.5) varies smoothly from +1.9 for completely inflexible small molecules to -2.2 for typically flexible large molecules. The mp coefficient (-0.007) remains practically constant, near the traditional value (-0.01) for most molecules, which suggests that the small-to-large molecule continuum is mainly solvation responsive, apparently with only minor changes in the crystal lattice contributions. For a test set of 32 large molecules (e.g., cyclosporine A, gramicidin A, leuprolide, nafarelin, oxytocin, vancomycin, and mostly natural-product-derived therapeutics used in infectious/viral diseases, in immunosuppression, and in oncology) the modified equation predicted the intrinsic solubility with a root-mean-square error of 1.10 log unit, compared to 3.0 by the traditional GSE, and 1.07 by RFR.

A sensitive in vitro performance assay reveals the in vivo drug release mechanisms of long-acting medroxyprogesterone acetate microparticles

Today, a growing number of subcutaneously administered depot formulations enable continuous delivery of poorly soluble compounds over a longer time period. The modified liberation is considered to be a rate-limiting step in drug absorption and thus impacts therapeutic efficacy and product safety. In the present approach, a mechanism-based pharmacokinetic model of the commercial microparticle formulation depo-subQ provera 104™ (Sauter mean diameter of 5.08 ± 1.63 µm) was established. The model was verified using human pharmacokinetic data from three different clinical trials. Further, the effects of drug release, injection site and patient population on the pharmacokinetic profile were investigated. For this purpose, the drug release was assessed using the novel dispersion releaser technology, whereby a biorelevant medium reflecting major characteristics of the subcutaneous tissue (including ion background, buffer capacity and protein concentration) was used. The established model provided an effective prediction of the key pharmacokinetic parameters, including C_max, T_max and AUC_all. Only in presence of 55% of fetal bovine serum (using a novel simulated subcutaneous interstitial fluid), the release assay was capable to discriminate between microparticles before and after storage.

Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Cephalexin Monohydrate

Literature data and results of experimental studies relevant to the decision to allow waiver of bioequivalence studies in humans for the approval of immediate release solid oral dosage forms containing cephalexin monohydrate are presented. Solubility studies were performed in accordance with the current biowaiver guidelines of the Food and Drug Administration, World Health Organization and European Medicines Agency, taking the degradation at some pH values into consideration. Together with solubility and permeability data for cephalexin monohydrate from the literature, it was demonstrated to be a Biopharmaceutics Classification System Class 1 drug. The pharmacokinetic behavior, results of bioequivalence studies published in the literature, as well as the therapeutic uses, potential toxicity and potential excipient effects on bioavailability were also assessed. Cephalexin has a wide therapeutic index and no bioequivalence problems have been reported. Dissolution studies were run under Biopharmaceutics Classification System-biowaiver conditions for the pure drug and 2 generic formulations available on the German market. Considering all relevant aspects, it was concluded that a biowaiver-based approval for products containing cephalexin monohydrate as the single active pharmaceutical ingredient is scientifically justified, provided that well-established excipients are used in usual amounts and that both test and reference dosage forms meet the guideline criteria of either "rapidly dissolving" or "very rapidly dissolving."

Solubility, Hansen Solubility Parameters and Thermodynamic Behavior of Emtricitabine in Various (Polyethylene Glycol-400 + Water) Mixtures: Computational Modeling and Thermodynamics

This study was aimed to find out the solubility, thermodynamic behavior, Hansen solubility parameters and molecular interactions of an antiviral drug emtricitabine (ECT) in various “[polyethylene glycol-400 (PEG-400) + water]” mixtures. The solubility of ECT in mole fraction was determined at “T = 298.2 to 318.2 K” and “p = 0.1 MPa” using an isothermal method. The experimental solubilities of ECT in mole fraction were validated and correlated using various computational models which includes “Van’t Hoff, Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models”. All the models performed well in terms of model correlation. The solubility of ECT was increased with the raise in temperature in all “PEG-400 + water” mixtures studied. The highest and lowest solubility values of ECT were found in pure PEG-400 (1.45 × 10⁻¹) at “T = 318.2 K” and pure water (7.95 × 10⁻³) at “T = 298.2 K”, respectively. The quantitative values of activity coefficients indicated higher interactions at molecular level in ECT and PEG-400 combination compared with ECT and water combination. “Apparent thermodynamic analysis” showed an “endothermic and entropy-driven dissolution” of ECT in all “PEG-400 + water” combinations studied. The solvation nature of ECT was found an “enthalpy-driven” in each “PEG-400 + water” mixture studied.

Chronopharmacology of glucocorticoids

Glucocorticoids influence a wide array of metabolic, anti-inflammatory, immunosuppressive, and cognitive signaling processes, playing an important role in homeostasis and preservation of normal organ function. Synthesis is regulated by the hypothalamic-pituitary-adrenal (HPA) axis of which cortisol is the primary glucocorticoid in humans. Synthetic glucocorticoids are important pharmacological agents that augment the anti-inflammatory and immunosuppressive properties of endogenous cortisol and are widely used for the treatment of asthma, Crohn's disease, and rheumatoid arthritis, amongst other chronic conditions. The homeostatic activity of cortisol is disrupted by the administration of synthetic glucocorticoids and so there is interest in developing treatment options that minimize HPA axis disturbance while maintaining the pharmacological effects. Studies suggest that optimizing drug administration time can achieve this goal. The present review provides an overview of endogenous glucocorticoid activity and recent advances in treatment options that have further improved patient safety and efficacy with an emphasis on chronopharmacology.