Compressed oxygen in drug stability experiments.

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 k(total) can be expressed as: k(total)=k(anaerobic) + k(aerobic), where k(anaerobic) and k(aerobic) are the rate constants of anaerobic and aerobic degradations, respectively. The k(anaerobic) can be expressed as k(anaerobic) = A(anaerobic) x exp(-E(a,anaerobic)/RT) according to Arrhenius equation, and the k(aerobic) was found to be k(aerobic) = A(aerobic) x exp(-E(a,aerobic)/RT) x p(O2) in our study.