Stability of Packaged Solid Dosage Forms. II. Shelf-life Prediction for Packaged Sugar-coated Tablets Liable to Moisture and Heat Damage

Shelf-life prediction for solid dosage forms that are affected by the moisture content and ambient temperature was investigated in moisture-semipermeable packages. In this study, the color change of a sugar-coated tablet containing ascorbic acid in the core was examined. The kinetics of the color change was studied on the basis of the empirical formulae described by Carstensen et al. A mathematical model, based on the kinetics of the color change and the moisture permeabilities of the packages, was derived in order to predict the shelf life of the tablets in strip pack or press-through pack under various atmospheric conditions. The mathematical model was used with an iterative calculation procedure with a time interval of several days, taking into account the fluctuations of temperature and relative humidity during storage. Reasonable agreement was found between the actual data and the predicted values. The iteration procedure using the mathematical model derived here was found to be useful for predicting the shelf life of solid dosage forms in moisture-semipermeable packages under various conditions of humidity and temperature.