title: Equivalence tests for shelf life and average drug content in stability studies.
abstract: Stability testing is a procedure frequently used in the pharmaceutical industry to estimate the shelf life of a drug. Hereby, a standard problem of interest is whether or not to pool a given number of batches to assign a single shelf life for the combined batches. In this paper, we propose two modified methods for the pooling process. One is based on the relative average drug contents of batches at a target shelf life, which basically involves specification of thresholds in relative terms, and the other is tests for the equivalence of shelf lives (using ratios of shelf lives) at a specified lower acceptance criteria of label claim. For both approaches, marginal and simultaneous confidence intervals are established. The methods will be illustrated using two different stability data. A simulation study is conducted to investigate the coverage probability of the proposed methods.
authors.affiliation: Department of Mathematics and Statistics, South Dakota State University, Harding Hall 123, Brookings, SD 57007, USA. gemechis.djira@sdstate.edu
authors.forename: Gemechis D
authors.initials: GD
authors.lastname: Djira
authors.forename: Ludwig A
authors.initials: LA
authors.lastname: Hothorn
authors.forename: Yi
authors.initials: Y
authors.lastname: Tsong
mesh_terms: D016001:Confidence Intervals; D004355:Drug Stability; D004356:Drug Storage; D015233:Models, Statistical; D011336:Probability; D013997:Time Factors