The influence of pH, temperature and buffers on the degradation kinetics of cefetamet pivoxil hydrochloride in aqueous solutions

The first-order hydrolysis kinetics of cefetamet pivoxil (CP) were investigated as a function of pH, temperature and buffers. The degradation was followed by HPLC. Buffer catalysis was observed in acetate and phosphate buffers. The pH-rate profiles for hydrolysis of cefetamet pivoxil were obtained at 333, 343, 353 and 363 K. The pH-rate expression was k(pH) = k(H+)a(H+) + k(H2O)k(OH-) a(OH-), where k(H+) and k(OH-) are the second-order rate constants (mol(-1) 1 s(-1)) for hydrogen ion activity and for hydroxyl ion activity respectively, and k(H2O) is the pseudo-first-order rate constant (s(-1)) for spontaneous reaction under the influence of water. The pH-rate profile was characteristically U-shaped. Maximum stability was observed in the pH region from 3 to 5. (C) 2004 Elsevier B.V. All rights reserved.