Compressed oxygen in drug stability experiments

Abstract

A drug stability experiment accelerated by compressed oxygen was established. The stability of 10% ascorbic acid solution as a model was studied and the kinetic parameters were obtained with the newly established experimental method. Because ascorbic acid degrades under both anaerobic and aerobic conditions, the total rate constant ktotal can be expressed as: ktotal=kanaerobic+kaerobic, where k anaerobic and kaerobic are the rate constants of anaerobic and aerobic degradations, respectively. The kanaerobic can be expressed as kanaerobic= Aanaerobic·exp(-E a,anaerobic/RT) according to Arrhenius equation, and the k aerobic was found to be kaerobic= A aerobic·exp(-Ea,aerobic/RT)·pO2 in our study. © 2007 Pharmaceutical Society of Japan.