Functionality improvement of Nimesulide by eutectic formation with nicotinamide: Exploration using temperature-composition phase diagram

Melting point depression for enhanced dissolution rate of eslicarbazepine acetate

BACKGROUND

Eslicarbazepine acetate (ESL) is antiepileptic agent which is approved for use as single therapy or in combination with other drugs. However, it suffers from poor oral bioavailability. Modulation of drug crystallinity can be utilized as an approach for enhancing drug dissolution.

OBJECTIVE

Accordingly, the aim of this study was to investigate possible eutectic system formation between eslicarbazepine with either tartaric acid or citric acid.

METHODOLOGY

Eslicarbazepine acetate was subjected to wet co-grinding with tartaric acid or citric acid at different molar ratios. The prepared formulations were assessed using Fourier-transform infrared (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry in addition to dissolution studies.

RESULTS

The characterization techniques confirmed eutectic system formation with tartaric and citric acid with the optimum molar ratio for eutexia being 1:1 for both substances. Development of eutectic systems significantly enhanced the dissolution rate of ESL. Increasing the ratio of tartaric acid higher than the optimum ratio for eutexia resulted in additional increase in drug dissolution rate. This suggested the impact of pH modification on drug dissolution rate. The enhanced dissolution rate in case of the formulations containing ESL and citric acid was accredited to combined effect of eutaxia and pH modulation. These explanations were proven from investigating the dissolution rate of the physical mixtures which were inferior in their dissolution rate compared with the prepared formulations.

CONCLUSION

co-processing of ESL with either citric acid or tartaric acid resulted in hastened dissolution rate which was accredited to combined effect of eutexia with pH modification.

RP-HPLC METHOD DEVELOPMENT, VALIDATION, AND ITS PHARMACOKINETIC APPLICABILITY IN PRECLINICAL EVALUATION OF RHEIN TREATED WITH NOVEL DIACEREIN EUTECTICS

The current study represents the bio-analytical method for the estimation of Rhein (Rh, an active metabolite of Diacerein (DIA)) in rats treated with novel DIA eutectics to investigate the pharmacokinetics of DIA. A simple protein precipitation technique was used to extract Rh and internal standard (IS), p-aminobenzoic acid, and injected into a Phenomenex Gemini C18 column. The separation was achieved by gradient elution comprising of ammonium acetate (10 mM; pH 3.0) and acetonitrile in 18 min of run time at a flow rate of 0.8 mL/min with the retention time of 11.8 min (Rh) and 5.9 min (IS). The results revealed that the proposed method was linear over the range of 200-20,000 ng/mL (r² > 0.9988) of Rh and proved to be precise and accurate. The method was fully validated as per the USFDA guideline and the pharmacokinetic study in rats was performed for Rh following oral administration of the pure DIA and newly developed eutectics. Therefore, the present method could be used to estimate DIA to illustrate the comparative pharmacokinetic analysis. This can be also applied to its related multi-component formulations for future study.

Preformulation Studies of Ezetimibe-Simvastatin Solid Dispersions in the Development of Fixed-Dose Combinations

Two active pharmaceutical ingredients (APIs) with limited solubility, simvastatin and ezetimibe, prepared as a drug-drug solid dispersion (SD) was evaluated for physicochemical, microstructural, and aqueous dissolution properties. The simvastatin-ezetimibe SD was prepared using the co-grinding method in a wide range of weight fractions and differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) were used to perform the phase composition analysis. DSC studies confirmed that simvastatin and ezetimibe form a simple eutectic phase equilibrium diagram. Analysis of Fourier transform infrared spectroscopy (FTIR) studies excluded strong interactions between the APIs. Our investigations have revealed that all studied dispersions are characterized by substantially improved ezetimibe dissolution regardless of simvastatin content, and are best when the composition oscillates near the eutectic point. Data obtained in our studies provide an opportunity for the development of well-formulated, ezetimibe-simvastatin fixed-dose combinations (for hypercholesterolemia treatment) with reduced ezetimibe dosages based on its dissolution improvement.

Thermal Behavior of the Nimesulide-Salicylic Acid Eutectic Mixtures Prepared by Mechanosynthesis and Recrystallization

Nimesulide, salicylic acid and their binary mixtures were studied by differential scanning calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR). The study of such systems is a promising and viable approach for solving the problem of poor solubility of materials in general and drug systems in particular. All areas of human activity are inextricably linked to materials, and thus, the study presented in the paper and not reported in the literature is very important and provides useful data for those working in various fields. The eutectic mixtures were obtained by mechanosynthesis and by recrystallization from ethanol over the entire 0-1 range of molar fractions. For both situations at the molar fraction of nimesulide 0.5, the mixture has a eutectic that suggests an increase in solubility at this composition. The interactions that take place between the components were determined with the help of the excess thermodynamic functions (G^E, S^E, µ^E), which highlight the deviation from the ideality of the considered binary systems.

Application of a Validated RP-HPLC Method in Solubility and Dissolution Testing for Simultaneous Estimation of Diacerein and Its Active Metabolite Rhein in Presence of Coformers in the Eutectic Tablet Formulation

The present study aimed to develop and validate a novel reversed-phase high-performance liquid chromatography method for simultaneous estimation of Diacerein (DIA) and Rhein (Rh, alkaline degradation product and active metabolite) in the presence of various coformers used to prepare eutectic oral formulation. Chromatographic separations were achieved on a Phenomenex Gemini C18 column (250 mm × 4.6 mm, 5 μm) placed in the thermostated column oven at 40°C. The mobile phase, comprising of acetonitrile and 10 mM ammonium acetate (pH 3.0), was eluted through the gradient system with 0.8 mL/min flow rate at 254 nm detection and analytical run time of 14 min. Additionally, the method was validated for specificity, linearity, precision, accuracy, selectivity, limit of quantitation, limit of detection and robustness as per International Conference on Harmonization guideline. The developed method was applied for the comparison of drug release profiles of pure DIA and from prepared eutectic formulations for the quantitation of DIA and Rh in the multicomponent adducts. The achieved method advocated their applicability in routine quality control analysis of DIA formulations without interference of degraded product and excipients.

Preparation and Characterization of Co-Processed Mannitol and Sorbitol Using NanoCrySP Technology

Particle engineering of excipients, at sub-particulate level using co-processing, can provide high functionality excipients. NanoCrySP technology has been recently explored as a novel approach for the generation of nanocrystalline solid dispersion of poorly soluble drugs, using spray drying process. The purpose of the present study was to generate co-processed mannitol and sorbitol (SD-CSM) using NanoCrySP technology having similar composition to commercial co-processed excipient (Compressol® SM, CP). The characterization of excipients was performed to evaluate their various physicomechanical properties. The sub-micron crystallite size of sorbitol in the matrix of mannitol was determined using the Williamson-Hall equation and Halder-Wagner equation. The reduction in crystallite size of sorbitol and mannitol, lower melting point, and lower heat of fusion of SD-CSM could be responsible for excellent compactibility, better tabletability, and comparable compressibility with respect to CP. This was confirmed by the compressibility-tabletability-compactibility (CTC) profile and Heckel plot analysis. Overall, SD-CSM generated using NanoCrySP technology improved functionalities of excipients over CP and would be useful for direct compression application.

Emerging Multi-Drug Eutectics: Opportunities and Challenges

Complexity and heterogeneous nature of most diseases have posed greater challenges in the modern healthcare system. Fixed-dose combination can offer an ideal way to improve patient compliance and higher therapeutic efficacy. However, biopharmaceutical issues associated with the drug combinations remain unaddressed. Multidrug eutectics (MDE) have demonstrated significant promise in improving the biopharmaceutical attributes with synergistic therapeutic action. Eutectic mixtures are the multicomponent solid forms that possess lesser melting point than the individual components at a fixed composition. Non-covalent linking of drug combinations as MDE is an innovative strategy with enhanced solubility, dissolution, and mechanical and potential therapeutic efficacy. This review provides a comprehensive overview of the design of MDE, rational selection of drugs, characterization tools, and their therapeutic potential. Besides, the futuristic perspective where MDE could make a significant impact on combination therapy is briefly outlined. Graphical Abstract.

Eutectic mixtures as an approach to enhance solubility, dissolution rate and oral bioavailability of poorly water-soluble drugs

Eutectic mixtures have been known for a long time in the pharmaceutical field. However, its potential as a system to improve the solubility and dissolution of poorly water-soluble drugs remains little explored. Studies involving the microstructural characterization and the preparation of solid dosage forms containing eutectic mixtures are also an issue to be developed. Recently, the number of studies involving the preparation of eutectic mixtures to improve the solubility and oral bioavailability of poorly soluble drugs has increased considerably, including drug-carrier and drug-drug mixtures. In this review is discussed the potential of eutectic mixtures as an alternative pharmaceutical solid system to enhance drugs solubility, dissolution rate or oral bioavailability. Different aspects like history, physico-chemical, microstructural properties, preparation methods, mechanisms involved in solubility/dissolution enhancement, techniques for solid state characterization, in vivo studies, advantages, limitations and formulation perspective are also discussed.

Sketching neoteric solvents for boosting drugs bioavailability

Emerging neoteric solvents are being the subject of growing attention due to their lower cost and environmental impact, so they are being applied in a broad spectrum of industries. Among them, the pharmaceutical sector is demanding new environmentally friendly and non-toxic solvents able to enhance drugs solubility and stability. The introduction of ionic liquids turned out to be a breakthrough in the field of Green Chemistry opening up new separation and catalysis opportunities. In this sense, the options represented by Deep Eutectic Solvents make up an attractive alternative due to the low cost of their raw material, simple synthesis, and eco-friendly character. In line with these findings, Therapeutic Deep Eutectic Solvents and Natural Deep Eutectic Solvents are new and promising alternatives to improve the bioavailability of drugs in pharmaceutical formulations. This leading article is focused on providing a general picture of the advantages and drawbacks of these new solvents as well as the main research lines and perspectives to achieve efficient drugs delivery systems.

How tenofovir disoproxil fumarate can impact on solubility and dissolution rate of efavirenz?

Efavirenz (EFZ) and tenofovir disoproxil fumarate (TDF) can be used simultaneously in the treatment of human immunodeficiency virus type1 infection. In this work the impact of TDF, a hydrophilic drug, on the solubility and dissolution rate of EFZ, a poorly water-soluble drug, was evaluated. EFZ/TDF binary mixtures in different molar ratios were prepared. Differential scanning calorimetry (DSC) results indicate the formation of a eutectic mixture, the molar ratio of 65/35 being the eutectic point. It was observed an increase in the EFZ solubility in water and acidic conditions (0.1 N HCl and biorelevant medium), in the presence of TDF. On the other hand, there was a decreasing on EFZ solubility in phosphate buffer pH 6.8, probably influenced by the lower solubility of TDF in this medium. The high solubility of TDF in water and acidic medium may have contributed to improve the solubility of EFZ, as well as the formation of a eutectic mixture, supported by X-ray powder diffraction (XRPD) and Fourier Transform infrared spectroscopy (FTIR) analyses. However, TDF solubility and dissolution rate was not significantly influenced by the presence of EFZ.