Orphan Drug Act (US, Public Law 97-414) and 21 CFR Part 316

The Orphan Drug Act of 1983 is the US law that gives developers of drugs and biologics for rare diseases three incentives: a tax credit for clinical testing, exemption from certain FDA user fees, and seven years of marketing exclusivity after approval. Its rules are in 21 CFR Part 316. A disease is rare if it affects fewer than 200,000 people in the US, or if costs cannot be expected to be recovered from US sales. Prion diseases are rare enough that a therapy for them would plausibly meet the test, but no source read here shows an FDA orphan designation for a prion product. The EU, not the US, holds the CJD orphan designations found. Information only, not regulatory advice.

Key facts

  • The Orphan Drug Act was added to the FD&C Act by Public Law 97-414, enacted 4 January 1983 (96 Stat. 2050).
  • Designation brings tax credits for qualified trials, exemption from user fees and potential seven years of exclusivity; it is separate from approval and the product gets the same scientific review as any other.
  • A rare disease affects fewer than 200,000 people in the US, or affects more but offers no reasonable expectation of recovering development and US sales costs; eligibility is judged as of the request date.
  • A sponsor must request designation before filing the marketing application, and must tell FDA if it stops pursuing approval.
  • 21 CFR Part 316 has six subparts: general provisions, written recommendations, designation (316.20 to 316.30), exclusive approval (316.31 to 316.36), open protocols and availability of information.
  • A designation request needs a scientific rationale drawing on in vitro, animal and clinical data, including negative results, plus prevalence or cost-recovery documentation.
  • Prevalence is the number of US persons diagnosed when the request is submitted; the cost route needs itemised costs, seven-year projected revenue and a CPA report.
  • The exclusivity bar runs 7 years from approval and covers only the approved use; it ends early on withdrawal or revocation, holder consent or failure to assure supply.
  • A "same drug" is judged by active moiety for small molecules and by principal molecular structural features for macromolecules; a clinically superior drug is not the same drug.
  • Clinical superiority means greater effectiveness, greater safety or a major contribution to patient care.
  • The tax credit is 25 percent of qualified clinical testing expenses, cut from 50 percent for tax years beginning after 2017; it applies to human testing after designation and before approval, excludes grant-funded amounts, and must be elected each year.
  • The application fee exemption sits at FD&C Act section 736(a)(1)(F) and is lost if the application includes a non-rare indication.
  • The Consolidated Appropriations Act 2026 (Pub. L. 119-75), signed 3 February 2026, narrowed the exclusivity bar to the same approved use or indication, overriding the Catalyst v. Becerra ruling; one law firm source reports it applies whatever the designation or approval date.
  • The Orphan Products Grants Program is tied to the Act: clinical trials grants since 1983, natural history grants since 2016, and rare neurodegenerative grants since the 2021 ACT for ALS.
  • Search results show EU orphan designations for CJD (NSC500, 2017; a further 2024 listing) but no FDA designation for a prion product; this is absence in search results, not a database check.

Timeline

  1. 1983Clinical Trials Grants Program begins; orphan drug credit added to the tax code for expenses after 1982.
  2. 1983Orphan Drug Act enacted as Public Law 97-414.
  3. 1992Orphan Drug Final Rule, the base of 21 CFR Part 316.
  4. 2013Orphan Drug Final Rule amends the regulations.
  5. 2016Natural History Studies Grants Program begins.
  6. 2017Statute requires clinical superiority for later sponsors of an otherwise identical drug.
  7. 2018(tax years beginning after 2017) Credit rate falls from 50 to 25 percent.
  8. 2021ACT for ALS creates rare neurodegenerative grants.
  9. 2026Pub. L. 119-75 changes exclusivity scope to same approved use or indication.

Last checked 1 November 2026

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