Definition · Plain-language
Orange Book
The Orange Book is the FDA publication formally titled "Approved Drug Products with Therapeutic Equivalence Evaluations", listing approved drug products together with their therapeutic-equivalence ratings.
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What the Orange Book is
The Orange Book — named for the colour of its original printed cover — is the FDA’s authoritative listing of drug products approved as safe and effective under the Federal Food, Drug, and Cosmetic Act. For each product it provides identifying information and, crucially, a therapeutic-equivalence evaluation. The publication is widely used by pharmacists, prescribers, payers and regulators to determine which products the FDA considers interchangeable, and it underpins state generic-substitution rules.
Therapeutic-equivalence (TE) codes
A central feature of the Orange Book is its therapeutic-equivalence coding. Products that the FDA considers therapeutically equivalent — pharmaceutically equivalent and bioequivalent, so that they can be expected to have the same clinical effect and safety profile when substituted — receive codes beginning with "A", such as AB. Products for which therapeutic equivalence has not been established receive codes beginning with "B". These ratings guide whether a generic product may be substituted for a reference brand product.
Patents and exclusivity
The Orange Book also lists patent and exclusivity information associated with approved drugs. Patent listings and periods of regulatory exclusivity affect when and how generic competitors can seek approval through the Abbreviated New Drug Application process, including the patent-certification framework that can trigger litigation timelines. By bringing approval status, therapeutic equivalence and intellectual-property information together in one resource, the Orange Book serves as a central reference point in the US generic-drug system.
Key facts
At a glance
- Definition: FDA list of approved drug products with equivalence evaluations.
- Full title: Approved Drug Products with Therapeutic Equivalence Evaluations.
- TE codes: "A" codes (e.g. AB) = therapeutically equivalent; "B" = not established.
- Use: Guides generic substitution for brand products.
- Also lists: Patent and exclusivity information for approved drugs.
- Publisher: US Food and Drug Administration.
Common misconceptions
What people often get wrong
Often heard: The Orange Book lists every drug, including unapproved ones.
Actually: The Orange Book lists drug products approved under the Federal Food, Drug, and Cosmetic Act. Unapproved products and biologics licensed under the Public Health Service Act are handled separately (biologics appear in the Purple Book).
Often heard: A therapeutic-equivalence rating measures which drug works best.
Actually: TE ratings indicate whether two products are pharmaceutically equivalent and bioequivalent, so they can be substituted for one another. They are a substitutability assessment, not a ranking of clinical superiority.
Often heard: An "AB" rating is a clinical recommendation to use a particular drug.
Actually: An AB rating signifies the FDA considers the products therapeutically equivalent and substitutable. It is a regulatory equivalence code, not advice on whether any individual should take a given drug.
