Abstract
In order to predict the shelf lives of solid dosage forms whose active ingredients are susceptible to damage by moisture and heat, the stabilities of aspirin aluminum tablets packaged in a press-through pack and a glass bottle were investigated in a storehouse. The degradation was found to follow apparent zero-order kinetics. Predictions of the stabilities of aspirin aluminum tablets in these packages were carried out by an iterative calculation over a time interval through a mathematical model in which the kinetic parameters of stability were combined with the moisture permeabilities of the packages. In this study, for the purpose of improving the reliability of shelf-life prediction, the effects of moisture and heat on aspirin aluminum stability were analyzed by a multiple regression technique on the basis of the Carstensen equation. The variation of the degradation rate constants was estimated to obtain their confidence limits with a certain probability. It was found that there was a good agreement between the observed data and the predicted values of the aspirin aluminum contents in the packaged tablets, and that the confidence limits of the degradation rate constants gave reliable shelf lives with the expected probability.
