21 CFR § 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study.

---
identifier: "/us/cfr/t21/s320.29"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 320.29 - Analytical methods for an in vivo bioavailability or bioequivalence study."
title_number: 21
title_name: "Food and Drugs"
section_number: "320.29"
section_name: "Analytical methods for an in vivo bioavailability or bioequivalence study."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "D"
subchapter_name: "DRUGS FOR HUMAN USE"
part_number: "320"
part_name: "BIOAVAILABILITY AND BIOEQUIVALENCE REQUIREMENTS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 321, 351, 352, 355, 371."
cfr_part: "320"
---


# 320.29 Analytical methods for an in vivo bioavailability or bioequivalence study.

(a) The analytical method used in an in vivo bioavailability or bioequivalence study to measure the concentration of the active drug ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products, or the method used to measure an acute pharmacological effect shall be demonstrated to be accurate and of sufficient sensitivity to measure, with appropriate precision, the actual concentration of the active drug ingredient or therapeutic moiety, or its active metabolite(s), achieved in the body.

(b) When the analytical method is not sensitive enough to measure accurately the concentration of the active drug ingredient or therapeutic moiety, or its active metabolite(s), in body fluids or excretory products produced by a single dose of the test product, two or more single doses may be given together to produce higher concentration if the requirements of § 320.31 are met.

[42 FR 1648, Jan. 7, 1977, as amended at 67 FR 77674, Dec. 19, 2002]