FDA Purple Book: Biologics, Biosimilars, and Exclusivity

The FDA Purple Book is a publicly searchable database maintained by the U.S. Food and Drug Administration that lists every biological product licensed for sale in the United States, along with each product’s exclusivity periods and, where applicable, patents disclosed during biosimilar litigation.¹ It covers products approved under both Section 351(a) of the Public Health Service Act (original biologics) and Section 351(k) (biosimilars and interchangeable products). Federal law requires the FDA to publish the list in a searchable electronic format and update it every 30 days as new products are licensed.²

What Each Entry Shows

Every product in the database carries a set of identifiers that let you pin down exactly which approval you’re looking at: the proprietary (brand) name, the nonproprietary scientific name, the Biologics License Application (BLA) number, the date of first licensure, and the license holder.¹ The licensure date does more work than it looks: it starts the clock on the exclusivity periods that determine when biosimilar competitors can enter the market.

Alongside those identifiers, each record shows any active exclusivity periods and, where applicable, patents that have been submitted through the patent exchange process between reference product sponsors and biosimilar applicants. The database covers products regulated by both of the FDA’s reviewing centers: the Center for Drug Evaluation and Research (CDER), which handles most therapeutic biologics including biosimilars, and the Center for Biologics Evaluation and Research (CBER), which covers vaccines, blood products, cellular and gene therapies, and allergenic products.¹

Reference Products, Biosimilars, and Interchangeable Products

The Biologics Price Competition and Innovation Act of 2009 created an abbreviated approval pathway so competitors don’t have to repeat the full clinical trial program the original product went through.³ The Purple Book uses three classifications to show where each product sits.

Reference Products

A reference product is the original biologic that went through the full licensing process under Section 351(a). Every biosimilar application names a specific reference product, and the Purple Book links each biosimilar back to the BLA number of its reference product so you can trace the lineage.

Biosimilars

A biosimilar is a biological product that is highly similar to a reference product despite minor differences in clinically inactive components, and that has no clinically meaningful differences in safety, purity, or potency.² Because biologics are made from living organisms rather than synthesized chemically, no two manufacturing processes produce identical molecules. The biosimilar standard demands functional equivalence, not molecular identity.

Interchangeable Products

Interchangeability is a higher bar. A product designated as interchangeable can be substituted for the reference product at the pharmacy without the prescribing doctor’s involvement.² That designation allows an interchangeable product to capture market share through automatic substitution at the point of dispensing, much like a generic drug.

Exclusivity Periods You Can Look Up

The Purple Book doesn’t just list products. It lists the legal clocks protecting them, which is often the main reason people search it.

Twelve-Year Reference Product Exclusivity

The most significant protection is the 12-year exclusivity period. The FDA cannot approve a biosimilar application until 12 years after the reference product’s date of first licensure.² There is also a 4-year bar on even submitting a biosimilar application, meaning no competitor can file its abbreviated application until four years after the reference product was first licensed.⁴ Each qualifying product’s entry shows the expiration date for this exclusivity.

The clock starts from the date of first licensure, which the statute defines narrowly. A supplemental approval for a new dosage form, delivery device, or route of administration by the same sponsor does not restart the clock. Neither does a structural modification that leaves safety, purity, or potency unchanged.⁴ That definition prevents sponsors from evergreening exclusivity through minor product tweaks.

Pediatric Exclusivity

If a sponsor conducts pediatric studies meeting the requirements of the Federal Food, Drug, and Cosmetic Act, both the 12-year and 4-year periods get an additional six months.⁴ The expiration date shown in the Purple Book already includes any pediatric extension.⁵

Orphan Drug Exclusivity

Biologics treating rare diseases can receive seven years of orphan drug exclusivity. When a product has both orphan exclusivity and the standard 12-year exclusivity, the FDA cannot license a biosimilar for the protected orphan indication until whichever period expires later.⁴ The orphan expiration date displayed in the database includes any applicable pediatric extension.⁵

First Interchangeable Exclusivity

The first biosimilar to earn an interchangeable designation for a given reference product gets its own exclusivity window, during which the FDA will not approve any other product as interchangeable with that same reference product. The end date is calculated as the earliest of several possible endpoints tied to commercial marketing and any patent litigation.² The Purple Book tracks these dates so competing manufacturers can plan around them.

How Patents Get Into the Database

Patent information enters the Purple Book in a way that surprises people used to the small-molecule system. The brand-name sponsor of a biologic has no obligation to disclose patents to the FDA upfront. Patents only appear after a biosimilar applicant files an abbreviated application and triggers the exchange informally called the patent dance.⁶

Once that exchange begins, the reference product sponsor must send its initial patent list, and any later updates, to the FDA within 30 days of providing them to the biosimilar applicant.² The FDA then publishes those patents and their expiration dates. The agency’s role is ministerial; it posts what it receives without evaluating whether the patents are valid, enforceable, or actually infringed.⁵

That structure creates a real blind spot. If no biosimilar application has been filed for a given reference product, no patents will appear, even if the sponsor holds dozens of relevant ones. Brand sponsors also have discretion over which patents they include in their initial list, so the Purple Book may not reflect the full scope of intellectual property protecting a product.

How It Differs from the Orange Book

The FDA maintains two databases, and mixing them up is easy. The Orange Book covers small-molecule drugs approved through New Drug Applications under the Federal Food, Drug, and Cosmetic Act. The Purple Book covers biological products licensed through Biologics License Applications under the Public Health Service Act.¹ A product approved as a small-molecule drug will not appear in the Purple Book.

The most consequential difference is patent listing. Orange Book sponsors must disclose their patents as part of every NDA, upfront, before any generic competitor enters the picture. Purple Book sponsors face no such obligation, and patents only appear once a biosimilar applicant files. For many biologics that haven’t yet attracted biosimilar competition, the Purple Book contains no patent information at all. A second difference: the Orange Book is barred by law from listing process patents (patents on how a drug is manufactured rather than what it is). The Purple Book has no such restriction, and process patents can and do appear when sponsors include them.

Transitioned Products Like Insulin

On March 23, 2020, a group of products that had previously been regulated as small-molecule drugs were reclassified as biologics under the Public Health Service Act. The most notable is insulin, but the transition also covered human growth hormone (somatropin), pancrelipase, certain fertility hormones, and a few others. Their existing drug approvals were automatically converted into biologics licenses, and they now appear in the Purple Book and can serve as reference products for future biosimilar applications.⁷ Competitors to these products now file under Section 351(k) as biosimilars rather than as generics.

How to Search It

The FDA’s portal at purplebooksearch.fda.gov offers two search modes. The simple search lets you type a brand name or scientific name, with an auto-populated list of matches appearing as you type.⁸ The advanced search adds filters for BLA number, applicant name, and other criteria, which helps if you want to see every product held by a specific company or look one up by application number.⁹

Results appear in a summary table you can sort by licensure date or alphabetically. Patent listings live on a separate page within the database, organized by reference product.⁶ If you need to work with the data offline, the FDA also provides a downloadable dataset that opens in spreadsheet software.¹⁰

1
U.S. Food & Drug Administration. About Purple Book
2
Office of the Law Revision Counsel. 42 USC 262 – Regulation of Biological Products
3
U.S. Food and Drug Administration. Biological Product Innovation and Competition
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U.S. Food and Drug Administration. Reference Product Exclusivity for Biological Products Filed Under Section 351(a) of the PHS Act
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U.S. Food & Drug Administration. Purple Book Database of Licensed Biological Products – FAQs
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U.S. Food & Drug Administration. Purple Book – Patent List
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U.S. Food and Drug Administration. Information for Patients About Regulatory Changes for Certain Biological Product Medications
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U.S. Food & Drug Administration. Purple Book – User Guide
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U.S. Food & Drug Administration. Purple Book – Advanced Search
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U.S. Food & Drug Administration. Purple Book Search