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In medicine and pharmacology, bioequivalence, or therapeutic equivalency, is "the relative equivalency in the efficacy of different modes of treatment of a disease, most often used to compare the efficacy of different pharmaceuticals to treat a given disease."[1]

Pharmaceutical bioequivalence

In a systematic review of drugs used for cardiovascular disease, 35 of 38 randomized controlled trials found bioequivalence.[2] The same study also found that in spite of these results, 53% of published editorials on the topic "expressed a negative view of generic drug substitution".

A second study, addressed the bioequivalence of the anticoagulant warfarin, which has been only available under the trade name Coumadin in North America until recently. Warfarin has a narrow therapeutic window and requires frequent blood tests of the International Normalized Ratio (INR) to make sure patients do not have a subtherapeutic or a toxic level. A study showed that replacing Coumadin with generic warfarin was safe.[3]

United States

In the United States, the Office of Generic Drugs of Food and Drug Administration (FDA) is dedicated to "dedicated to approving safe, effective, high-quality and bio-equivalent generic drug products for use by consumers".[4] The approval process for generic drugs began in the late 1960s. Generic drug manufacturers are required to prove that their formulation exhibits bioequivalence to the innovator product.

After testing, the FDA assigns "Therapeutic Equivalence Evaluations Codes", or AB ratings.[5][6] Drugs considered therapeutically equivalent are given a rating of AB, AA, AN, AO, AP, or AT.

Generic drugs have been recalled for lack of bioequivalence.[7][8]

Independent laboratories

ConsumerLab conducts independent testing.


  1. Anonymous (2023), Bioequivalence (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. Kesselheim AS, Misono AS, Lee JL, et al (December 2008). "Clinical equivalence of generic and brand-name drugs used in cardiovascular disease: a systematic review and meta-analysis". JAMA 300 (21): 2514–26. DOI:10.1001/jama.2008.758. PMID 19050195. Research Blogging.
  3. Pereira JA, Holbrook AM, Dolovich L, Goldsmith C, Thabane L, Douketis JD, Crowther MA, Bates SM, Ginsberg JS. (2005). "Are brand-name and generic warfarin interchangeable? Multiple n-of-1 randomized, crossover trials.". Ann Pharmacother 39 (7-8): 1188-93. PMID 15914517.
  4. Anonymous. Welcome to the Office of Generic Drugs. Food and Drug Administration. Retrieved on 2009-02-01.
  5. Anonymous. Orange Book Annual Preface. Food and Drug Administration. Retrieved on 2009-02-02.
  6. (October 2002) "Generic Drugs". Med Lett Drugs Ther 44 (1141): 89–90. PMID 12405134[e] Free access
  7. ETHEX Corporation Issues Nationwide Voluntary Recall of Products. Food and Drug Administration (2009). Retrieved on 2009-01-29.
  8. ETHEX Corporation Initiated Nationwide Voluntary Recall of a Single Lot of Hydromorphone HCl 2 mg Tablets Due to Potential for Oversized Tablet (2008). Retrieved on 2009-01-29.