Comparing treatment variances in repeated measures bioavailability trials

In repeated measures bioavailability/bioequivalence studies involving two formulations, the underlying measurements, such as the area under the plasma concentration-time curve (AUC) and the maximum plasma concentration (Cmax), typically have a block compound-symmetric covariance matrix. To test the equality of the variances in such a covariance matrix, we derive in this paper an exact test and four asymptotic tests. We compare these tests using simulation to determine those that have good performance in terms of controlling the type I error rate as well as providing good power. We provide an example to demonstrate the proposed method.