21 CFR §320.35
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
If a bioequivalence requirement specifies a currently available in vitro test or an in vitro bioequivalence standard comparing the drug product to a reference standard, the manufacturer shall conduct the test on a sample of each batch of the drug product to assure batch-to-batch uniformity.