Stability of Packaged Solid Dosage Forms. I. Shelf-life Prediction for Packaged Tablets Liable to Moisture Damage

Deterioration of solid dosage forms due to the change of moisture content was investigated in moisture-semipermeable packages, including overwrapped packaging systems. For the purpose of predicting the shelf life in a drug-package combination, a mathematical model based on the physico-chemical properties of the drug and the moisture permeabilities of the packaging materials was derived. The mathematical model was incorporated with an iteration procedure over a time interval of several days, taking into account the fluctuations of temperature and relative humidity during prolonged storage. In this study, changes in the hardness of lactose-cornstarch tablets were investigated in strip packs and press-through packs with or without an overwrap film. The values of the hardness and the moisture content for the tablets in these moisture-semipermeable packages were studied under various atmospheric conditions, and were also predicted by means of the iteration procedure. There was reasonable agreement between the actual data and the predicted values, indicating that the iteration procedure through the mathematical model derived here is useful for the shelf-life prediction.