Repurposing Existing Drugs for New Uses: A Cohort Study of the Frequency of FDA-Granted New Indication Exclusivities Since 1997

Among 197 new drugs that subsequently experienced generic entry between 1997 and 2020, only 32% received at least one new indication added, with the probability of a new indication peaking above 4% at 7-8 years before generic entry and declining to near zero 15 years post-approval. The findings suggest that current indication-specific exclusivity periods are insufficient to incentivize drug repurposing, and policymakers should consider strengthening incentives to encourage clinical investigations for novel uses of existing drugs.