Comparing distributions of shelf lives for drug products with two components under different designs

To reduce the cost of stability testing in drug research and development, both bracketing and matrixing designs are recommended in the U.S. Food and Drug Administration's (FDA) guidelines for drug products with a single active ingredient (component). When the drug product contains multiple active components, the naïve approach is to take the minimum of shelf lives obtained from individual components as the labeled shelf life. The purpose of this article is to compare the distributions of the shelf life obtained as the minimum shelf life of two components for full FDA's sampling plan, matrixing, and bracketing designs. The results were obtained based on theoretical considerations and simulation studies.