Hitesh P. Chokshi

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Miscibility of drug and polymer is one of the key parameters in amorphous formulation design. The purpose of this work is to provide a theoretical approach to evaluate miscibility between drug and polymer in amorphous solid dispersions. The model system is indomethacin and polyvinylpyrrolidone-vinyl acetate copolymer. The Flory-Huggins (F-H) interaction(More)
The present work deals with improving the solubility of vemurafenib, a practically insoluble drug, by converting it into an amorphous-solid dispersion using a solvent-controlled precipitation process. The dispersion containing vemurafenib and hypromellose acetate succinate (HPMCAS), an enteric polymer, is termed microprecipitated bulk powder (MBP), in which(More)
Biorelevant dissolution test methods for lipid formulations of RZ-50, an experimental Roche compound, were developed and compared with standard compendial methods in terms of their in vivo predictability. Release of RZ-50, a poorly soluble weakly acidic drug, from lipid suspensions filled in soft gelatin capsules was studied in compendial and biorelevant(More)
A technique of using size exclusion chromatography (SEC) with the Corona charged aerosol detector (CAD) was developed and evaluated in comparison with refractive index (RI) and evaporative light scattering detection (ELSD) for fast screening of polyethylene glycol (PEG), a polymer used in preparing pegylated pharmaceutical compounds. These detection(More)
Drug and polymer mixing status in amorphous solid dispersions, an important aspect with regard to the physical stability and in vivo performance of such systems, was evaluated in this report with two case studies. In the first case study, the mixing between the drug and the polymer in an amorphous solid dispersion was assessed at both particulate and bulk(More)
Human biorelevant media have been shown to be a useful tool in pharmaceutical development and to provide input for in silico prediction of pharmacokinetic profiles after oral dosing. Dogs, in particular Beagles, are often used as animal models for preclinical studies. Key differences in the composition of human and canine gastric and intestinal fluids are(More)
A method is presented for determining the equilibrium solubility of a drug in a solid polymer at or near room temperature, which represents a typical storage temperature. The method is based on a thermodynamic model to calculate the Gibbs energy change ΔG(SS) associated with forming a binary drug-polymer solid solution from the unmixed polymer and solid(More)
The selection of media in dissolution method development can sometimes be an arbitrary decision. The case studies in this article give a practical rationale that should help in selecting media, especially surfactants. Three cases were studied: (1) the role of surfactants versus compound stability in the dissolution medium during dissolution method(More)
The mechanism of the oxalate/hydrogen peroxide chemiluminescence reaction has been examined by magnetic resonance techniques. Investigation of the reactive intermediates involved in chemiluminescence was carried out with bis(2,6-difluorophenyl)oxalate (DFPO) using 19F NMR to probe its reactions with aqueous hydrogen peroxide. Formation and reactions of the(More)
A novel method was developed to manufacture amorphous formulations of poorly soluble compounds that cannot be processed with existing methods such as spray drying and melt extrusion. The manufacturing process and the characterization of the resulting amorphous dispersion are presented via examples of two research compounds. The novel process is utilized(More)