Criteria for selecting pharmacokinetic repeat study samples

The pharmacokinetic (PK) repeat study sample, selected by the study pharmacokineticist, requires repeat bioanalysis because the concentration is incongruous with drug plasma concentration versus time profile. The inconsistency could be due to a number of reasons, including the detectable drug concentration in a predose sample or a sample from a placebo control group or a significant double peak in the terminal phase of an individual plasma concentration versus time profile that is not consistent with the profiles from other subjects in the same dose group. The justification for selecting the PK repeat sample should be clearly documented. The repeat analysis...