Importance of activation energy in drug stability: determination of activation energy of p-nitrophenyle acetate

ABSTRACT

Drug decomposition or degradation occurs during storage because of chemical reaction of the active ingredients or additives. The knowledge of chemical kinetic is useful to evaluate the shelf life [expiry date] and Stability of drugs. Several factors affecting the reaction rates including the effect of temperature which was quantitatively determined. In this study the hydrolysis of p-nitrophenyl acetate in phosphate buffer pH 8.5 was followed spectrophotometrically by measuring the increase in absorption at 398.5 nm caused by the liberation of p-nitrophenol to determine the activation energy in kilojoules per rmol and Kilocalreis per mole using Arrhinus equation and was found to be 5.27 Kilo calreis/mol. And 22.10 Kilo Joules per mole. Moreover pseudo first-order rate constant for the hydrolysis of p-nitrophenyl acetate was observed