Regulations (21 CFR 320.38 and 320.63) for Retention Samples.
The Division of Scientific Investigations (DSI) and FDA field investigators conduct inspections of clinical and analytical sites that perform bioavailability (BA) and bioequivalence (BE) testing for drug manufacturers seeking approval of a drug product. One of the most common findings from these inspections is the absence of retention samples by the testing facility where the study was conducted. The regulations regarding retention samples of test articles can be found in 21 CFR 320.38 and 320.63. The final rule on these regulations can be found in the Federal Register Notice, Vol. 58, No. 80, April 28, 1993.