Claim
FDA’s Orange Book assigns therapeutic equivalence (TE) codes to multisource drug products. First letter A means FDA considers the product therapeutically equivalent to other pharmaceutically equivalent products (including AB when bioequivalence issues were resolved with adequate evidence). First letter B means FDA does not currently consider it therapeutically equivalent. AB1/AB2-style three-character codes apply when multiple reference listed drugs exist under the same heading — products are TE only to others with the same three-character code.
Plain
A-rated (incl. AB) = therapeutically equivalent under Orange Book. B-rated ≠ TE. Matching AB1/AB2 matters when multiple RLDs exist. State substitution law still applies.
Citations
- FDA — Orange Book Preface (therapeutic equivalence codes) (
Orange Book Preface — A/B and AB codes) — source"A" products are those for which there are no known or suspected bioequivalence problems or for which actual or potential bioequivalence problems have been resolved with adequate in vivo and/or in vitro evidence supporting bioequivalence. ... Products meeting necessary bioequivalence requirements ... Multisource drug products ... generally will be coded AB if data and information are submitted demonstrating bioequivalence.
retrieved 2026-09-08