Stability analysis for drugs with multiple active ingredients

Abstract For every drug product on the market, the United States Food and Drug Administration (FDA) requires that an expiration dating period (shelf‐life) must be indicated on the immediate container label. For determination of the expiration dating period of a drug product, regulatory requirements and statistical methodology are provided in the FDA and ICH Guidelines. However, this guideline is developed for drug products with a single active ingredient. There are many drug products consisting of multiple active ingredients, especially for most traditional Chinese medicine. In this article, we propose a statistical method for determining the shelf‐life of a drug product with multiple active ingredients following similar idea as suggested by the FDA and assuming that these active ingredients are linear combinations of some factors. Stability data observed from a traditional Chinese medicine were analysed to illustrate the proposed method. Copyright © 2006 John Wiley & Sons, Ltd.