FDA Purple Book: search biologics, biosimilars, interchangeables, and patents

The FDA Purple Book is the FDA’s public database of every biological product licensed under the Public Health Service (PHS) Act: 351(a) reference biologics, 351(k) biosimilars, and interchangeable biosimilars. It also lists the patents that BLA holders publish under the Biological Product Patent Transparency Act. This tool is a fast, source-linked interface over the official Purple Book data — search by product, applicant, proper name, or BLA number above.

A 351(a) application is an original (reference) biologic with a full license; a 351(k) application is a biosimilar that relies on FDA’s prior finding for a reference product. Unlike small-molecule generics — which are exact copies and live in the Orange Book — biologics are large, complex molecules, so a biosimilar is "highly similar" rather than identical. Browse the full list of FDA-approved biosimilars by reference product.

All interchangeables are biosimilars, but not all biosimilars are interchangeable. An interchangeable biosimilar meets the additional 351(k)(4) standard, allowing pharmacy-level substitution for the reference product without prescriber involvement, subject to state law. Interchangeability is a substitution status, not a measure of clinical superiority. Filter by license type above to list only biosimilars or only interchangeables.

A reference biologic carries 12 years of reference-product exclusivity from first licensure, and a biosimilar cannot be submitted until 4 years after. Each product also lists the patents exchanged in the statutory "patent dance." To look up a specific biologic, type its BLA number (e.g. "761234") into the search box — you land on its record with license type, applicant, approval and exclusivity dates, and published patents. Use the Timeline view to see which reference products lose protection soon and which biosimilars are queued behind them.