KINETICS OF ASPIRIN HYDROLYSIS IN AQUEOUS SOLUTION OF SURFACTANTS I- NON-IONIC SURFACTANTS

Document Type : Original Article

Authors

1 Department of Pharmaceutics, Faculty of Pharmacy, Assiut University, Assiut, Egypt

2 Department of Pharmaceutics, Faculty of Pharmacy, University of Connecticut, USA

Abstract

The kinetics of aspirin hydrolysis were studied in the presence of different concentrations of polysorbates and at a variety of pH range. The aspirin hydrolysis in the presence of polysorbates followed first-order kinetics and the observed rate constants at different pH values and in the presence of the surface-active aaents were calculated. The surfactant effect ratio (SER) was calculated and found to be decreased as the surfactant concentration was increased. The micellar rate constant, Km , for the drug in the presence of the tested surfactants at a given pH value as well-as the distribution coefficient, K, of aspirin between the micellar and the aqueous phases were estimated. From the results obtained, it could be observed that the Km and K values are markedly influenced by the pH value of the system. The study revealed that the surfactants are not only used to solubilize those poorly water soluble compounds but also to increase their stability in aqueous solutions.