Drugs in control samples in nonclinical safety studies: a reconsideration

Abstract In nonclinical safety studies, independent on the route of administration, it is not uncommon that the test item and even its metabolites are detected, or quantified at multiples of the LLOQ in biological samples obtained from control group animals or in day 0 predose samples. Control samples in nonclinical safety studies are usually obtained from body fluids, mostly blood/plasma, but also from tissues. In clinical studies, contamination of placebo or day 0 predose samples is very rare, which is mainly due to the much lower administered doses, the type of drug formulation and administration, and the place of preparation...