OBJECTIVE: We evaluated the uptake of medicines licensed as orphan drugs by the United States Food and Drug Administration (FDA) or European Medicines Agency (EMA) into the WHO Model list of essential medicines and the WHO Model list of essential medicines for children from 1977 to 2021.

METHODS: We collated and analysed data on drug characteristics, reasons for adding or rejecting medicines, and time between regulatory approval and inclusion in the lists. We compared trends in listing orphan drugs before and after revisions to the inclusion criteria of the essential medicines lists in 2001, as well as differences in trends for listing orphan and non-orphan drugs, respectively.

FINDINGS: The proportion of orphan drugs in the essential medicines lists increased from 1.9% (4/208) in 1977 to 14.6% (70/478) in 2021. While orphan drugs for communicable diseases have remained stable over time, we observed a considerable shift towards more orphan drugs for noncommunicable diseases, particularly for cancer. The median period for inclusion in the essential medicines lists after either FDA or EMA first approval was 13.5 years (range: 1-28 years). Limited clinical evidence base and uncertainty about the magnitude of net benefit were the most frequent reasons to reject proposals to add new orphan drugs to the essential medicines lists.

CONCLUSION: Despite lack of a global definition of rare diseases, the essential medicines lists have broadened their scope to include medicines for rare conditions. However, the high costs of many listed orphan drugs pose accessibility and reimbursement challenges in resource-constrained settings.

Original languageEnglish
Pages (from-to)22-31
Number of pages10
JournalBulletin of the World Health Organization
Issue number1
Early online date31 Oct 2023
Publication statusPublished - 1 Jan 2024


  • Child
  • Drug Approval
  • Drugs, Essential
  • Humans
  • Orphan Drug Production
  • Pharmaceutical Preparations
  • Rare Diseases/drug therapy
  • United States
  • World Health Organization


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