Kinetics study of hydrochlorothiazide lactose liquid state interaction using conventional isothermal arrhenius method under basic and neutral conditions

ABSTRACT The Maillard reaction of hydrochlorothiazide (HCTZ) and lactose has been previously demonstrated in pharmaceutical formulations. In this study, the activation energy of - hydrohlorothiazide and lactose interaction in the liquid state was ascertained under basic and neutral conditions. Conventional isothermal High Performance Liquid Chromatography (HPLC) technique was employed to ascertain the kinetic parameters using Arrhenius method. Results: The activation energy obtained was 82.43 and 100.28 kJ/mol under basic and neutral conditions, respectively. Consequently, it can be inferred that Maillard reaction is significantly affected by pH, which can be used as a control factor whenever the reaction potentially occurs.

In-vitro bioequivalence study of 8 brands of metformin tablets in Iran market.

Bioequivalence studies are the commonly accepted methods displaying therapeutic equivalence between two products .This study was conducted to evaluate the bioequivalence between different formulations of metformin 500 mg and 1000 mg tablets which were marketed in Iran, and innovator brand. Considering that only in vitro bioequivalence studies can predict the in vivo bioequivalence, and to save time and cost, three essential in vitro tests including assay, weight variation and a comparative in vitro dissolution study were performed. In order to compare formulations, dissolution profiles were taken and compared through two model independent methods, difference factor (f1) and similarity factor (f2). All the tested brands released more than 80% drug in 30 minutes and contained 95-96.3% of labeled amount except b and C. The acceptance value in all cases were below 15. Therefore it is evident that test products except brand C were bioequivalent to the reference product, and could be used as a generic substitute for the innovator product. Results emphasize to need for post marketing investigation for new formulations.