Preparation and in vivo ocular absorption studies of disulfiram solid dispersion

Pharmaceutical assessment of polyvinylpyrrolidone (PVP): As excipient from conventional to controlled delivery systems with a spotlight on COVID-19 inhibition

Polyvinylpyrrolidone (PVP) is a water-soluble polymer obtained by polymerization of monomer N-vinylpyrrolidone. PVP is an inert, non-toxic, temperature-resistant, pH-stable, biocompatible, biodegradable polymer that helps to encapsulate and cater both hydrophilic and lipophilic drugs. These advantages enable PVP a versatile excipient in the formulation development of broad conventional to novel controlled delivery systems. PVP has tunable properties and can be used as a brace component for gene delivery, orthopedic implants, and tissue engineering applications. Based on different molecular weights and modified forms, PVP can lead to exceptional beneficial features with varying chemical properties. Graft copolymerization and other techniques assist PVP to conjugate with poorly soluble drugs that can inflate bioavailability and even introduces the desired swelling tract for their control or sustained release. The present review provides chemistry, mechanical, physicochemical properties, evaluation parameters, dewy preparation methods of PVP derivatives intended for designing conventional to controlled systems for drug, gene, and cosmetic delivery. The past and growing interest in PVP establishes it as a promising polymer to enhance the trait and performance of current generation pharmaceutical dosage forms. Furthermore, the scrutiny explores existing patents, marketed products, new and futuristic approaches of PVP that have been identified and scope for future development, characterization, and its use. The exploration spotlights the importance and role of PVP in the design of Povidone-iodine (PVP-I) and clinical trials to assess therapeutic efficacy against the COVID-19 in the current pandemic scenario.

Design and evaluation of topical solid dispersion composite of voriconazole for the treatment of ocular keratitis

Aim: The objective of present investigation was to increases solubility of voriconazole by using solid dispersion techniques and the development of solid dispersion-based voriconazole ophthalmic solutions. Materials & methods: The saturation solubility of solid dispersion containing polyvinylpyrrolidone K90 (PVPK-90) was found to increase the solubility of voriconazole compare other carrier like polyethylene glycol and Polyvinylpyrrolidone K 30 (PVPK-30). Solid dispersion of voriconazole was characterized by saturation solubility, Fourier-transform infrared spectroscopy and Differential scanning calorimetry study. Results & conclusion: The Fourier-transform infrared spectroscopy and Differential scanning calorimetry studies of voriconazole-based solid dispersion confirmed the complete changes in original polymorphic form of voriconazole. The antifungal assay showed that the maximum zone of inhibition was produced from optimized ophthalmic formulation containing sodium alginate as compared with other formulations and marketed eye drops.

Disulfiram thermosensitive in-situ gel based on solid dispersion for cataract

To improve the corneal permeability and water-solubility of disulfiram (DSF), which is an ocular drug for cataract, P188 was selected as a matrix to prepare solid dispersion of DSF (DSF_SD) by hot melt method. The DSF_SD was characterized by DSC, XRD, and IR, and the results suggested that DSF was amorphous in DSF_SD. The DSF_SD was added to borate buffer solution (BBS) contained 20% poloxamer P407 and 1.2% poloxamer P188 to form in-situ gel. In vitro and in vivo experiments revealed that DSF_SD combined with in-situ gel (DSF_SD/in-situ gel) increased the residence time and the amount of DSF penetrated through the corneal. The pharmacodynamics studies exhibited DSF_SD/in-situ gel delayed the development of selenium-induced cataract at some content. These results investigated that DSF_SD/in-situ gel as a drug delivery system can improve DSF ocular permeability.

Pharmaceutical Approach to HIV Protease Inhibitor Atazanavir for Bioavailability Enhancement Based on Solid Dispersion System

Atazanavir (ATV) is a low oral bioavailability (BA) compound and, clinically, is generally coadministrated with ritonavir (RTV), which boosts the oral BA of ATV by inhibiting cytochrome P450 (CYP) 3A, and P-glycoprotein (Pgp) via the same metabolic pathway. However, depending on pharmacokinetic interaction, RTV-boosted ATV has great potential for other comedication. In this study we demonstrated the pharmaceutical approach to BA improvement of ATV without RTV in rats, based on the solid dispersion system using sodium lauryl sulfate (SLS) as a carrier and Gelucire 50/13 as an absorption enhancer. ATV solid dispersions in SLS were prepared by a conventional solvent method and, at ratios of ATV to SLS of 1 : 2 and 1 : 3, were demonstrated to form an amorphous state in powder X-ray diffraction (PXRD) analysis and exhibited 2.26- and 2.36-fold improvement in a dissolution test in comparison to bulk ATV, respectively. After oral administration to rats, ATV solid dispersion in SLS at a ratio of 1 : 2 showed a 3.5-fold increase in BA compared with bulk ATV. Moreover, the addition of Gelucire 50/13 to ATV solid dispersion, at a total ratio of Gelucire 50/13, ATV and SLS 1 : 1 : 2 gave 7.0- and 4.7-fold increase in Cmax and BA compared with bulk ATV, respectively, when the relative BA to RTV-boosted ATV reached 93%. The results in this study proved that a pharmaceutical approach could improve the bioavailability of ATV without pharmacokinetic interaction with RTV.

Bioavailability enhancement of a COX-2 inhibitor, BMS-347070, from a nanocrystalline dispersion prepared by spray-drying

Spray drying drug with excipients is usually associated with the preparation of microcrystalline or amorphous drug in order to improve bioavailability. It was found that BMS-347070, when spray-dried with Pluronic F127 from acetone or methylene chloride, was dispersed as nanosized crystalline drug within the water-soluble Pluronic matrix. The reduction in drug particle/crystallite size, coupled with wetting by the Pluronic, resulted in a fast-onset formulation with bioavailability comparable to that of a solubilized and a NanoCrystal formulation. For this system, it is theorized that the polyethylene oxide segments of Pluronic crystallize and that the polypropylene oxide segments remain amorphous, providing a size-restricted domain in which the COX-2 drug crystallizes. This results in improved bioavailability while limiting the potential risk of conversion of an amorphous drug to its crystalline state.

Radiation protection by diethyldithiocarbamate: protection of membrane and DNA in vitro and in vivo against gamma-radiation

Diethyldithiocarbamate (DDTC) is studied for its antioxidant and radioprotective abilities. DDTC at a concentration of 0.5 mM reduced DPPH radical. DDTC reduced the damage to deoxyribose resulting from hydroxyl radicals generated by Fenton reaction, indicating that the radioprotective abilities of this compound could be due to the free radical scavenging. DDTC protected rat liver microsomal membranes in vitro from peroxidative damage in lipids (measured as TBARS) resulting from 50 Gy gamma-radiation. It also protected plasmid pBR322 DNA from radiation-induced strand breaks. An oral administration of DDTC to mice before whole body gamma-radiation exposure (4 Gy) resulted in a reduction of radiation-induced lipid peroxides in the liver homogenates. An administration of DDTC to mice before gamma-radiation reduced the radiation-induced DNA damage as studied by single cell gel-electrophoresis (comet assay). The comet parameters such as tail length, tail moment, and percent of DNA in tail were found to increase in the blood leukocytes of mice exposed to 4 Gy gamma-radiation. When DDTC was administered to mice before the radiation exposure, the increase in the comet parameters as a result of radiation was prevented, indicating a protection of cellular DNA. The present study has implication for the potential use of DDTC as a radioprotector.

Delay of cataract development in hereditary cataract UPL rats by disulfiram and aminoguanidine

The UPL rat is a newly developed hereditary cataract model. We previously found that the administration of disulfiram, a dimer of diethyldithiocarbamate that possesses antioxidant activity, and aminoguanidine, which is known to inhibit inducible nitric oxide synthase, inhibits cataract development in selenite-induced cataract rats. In this study, we investigated the anti-cataract effects and mechanism of disulfiram and aminoguanidine on UPL rats. The opacities of UPL rat lenses, as documented by the anterior eye segment analysis system, EAS-1000 (Nidek, Aichi, Japan), increased from 39 days, and apparently mature cataracts were observed at 53 days. Accompanied with the increase in lens opacity, glutathione concentrations in UPL rat lenses decreased. The Na(+) to K(+) and water-insoluble to water-soluble protein ratios, as well as the Ca(2+) contents in UPL rat lenses increased with the development of cataracts. Oral administration of disulfiram and aminoguanidine delayed the lens opacification as well as the changes in glutathione, Na(+) to K(+) ratio, water-insoluble to soluble protein ratio, and Ca(2+) content in UPL rat lenses. The opacity and Ca(2+) content of UPL rat lenses were closely associated. The present study demonstrates that disulfiram and aminoguanidine have potency of the delay of cataract development in UPL rats, probably caused by inhibiting the rise in Ca(2+) levels.