Purple Book(Purple Book)
FDA's database of biological products licensed under the Public Health Service Act, including originator biologics and biosimilars.
Usage Examples
- The biosimilar sponsor confirmed the reference product's 12-year exclusivity had expired via the Purple Book.
- The Purple Book listing showed three biosimilars already licensed against the same reference product.
- FDA granted interchangeable designation, updated in the Purple Book on approval.
What is Purple Book?
The Purple Book — officially Lists of Licensed Biological Products with Reference Product Exclusivity and Biosimilarity or Interchangeability Evaluations — is FDA's searchable database of biologics licensed under section 351(a) of the Public Health Service Act, plus biosimilars and interchangeable products licensed under section 351(k). It is the biologics counterpart to the Orange Book.
Entries identify the biological product name, BLA number, licensing date, reference product status, biosimilarity evaluations, and interchangeability designations. Reference product exclusivity periods — 12 years for originator biologics under the BPCIA — are tracked in the Purple Book.
Biosimilar sponsors rely on the Purple Book to identify the reference product, confirm exclusivity timing, and understand existing biosimilar or interchangeable designations for the same reference product. Interchangeable biologics — a higher regulatory bar than biosimilarity — can be substituted for the reference product at the pharmacy level under state law, similar to AB-rated generics.
Regulatory Context
This term appears most often in submission & approval workflows where submission quality, regulatory evidence, and audit readiness depend on consistent language. It is commonly referenced alongside PHSA SECTION 351, BPCIA.
When This Matters
- The biosimilar sponsor confirmed the reference product's 12-year exclusivity had expired via the Purple Book.
- The Purple Book listing showed three biosimilars already licensed against the same reference product.
- FDA granted interchangeable designation, updated in the Purple Book on approval.
Common Mistakes
- Treating submission readiness as a formatting-only check without lifecycle validation.
- Using outdated guidance references across modules and summaries.
- Missing cross-functional review between RA, CMC, and quality before submission.
Related Regulations
Frequently Asked Questions
Interchangeable designation requires a biosimilar to meet the biosimilarity standard plus demonstrate that it can be expected to produce the same clinical result as the reference product in any given patient, and — for multiple-dose products — that switching between the biosimilar and reference does not increase safety or efficacy risks.
The BPCIA grants 12 years of reference product exclusivity (including 4 years of data exclusivity where no biosimilar application can be submitted) from the date of first licensure. An additional 6 months of pediatric exclusivity may extend this.
Biologics are licensed under the Public Health Service Act, not the Federal Food, Drug, and Cosmetic Act. The Orange Book is the FDCA drug list. Biologics approved under early-era NDAs are still transitioning to BLA status and appear in both books during the transition.
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