Abstract
Background
Drug repurposing describes the approval of an already authorized medicine for a new therapeutic indication. Rising development costs, long clinical timelines and attrition in first-in-class discovery have renewed interest in this strategy as a way to extend pharmacological value using pre-validated mechanisms. This study evaluates how repurposing has contributed to pharmaceutical innovation over four decades, examining approval patterns, therapeutic redirection and industry behavior.
Methods
A longitudinal dataset of all new molecular entities and biologic products approved by the United States regulator between 1985 and 2024 was constructed. Repurposing was defined strictly as a new therapeutic indication distinct from the original approval. All cases were verified using regulatory documentation. Descriptive analyses quantified approval volumes, therapeutic transitions, applicant trajectories and development intervals. We compared the time to repurposing when development remained within the original company versus when rights transferred externally.
Results
Here we show that 451 drugs received subsequent approval for a new therapeutic use, representing a substantial fraction of authorized medicines. Oncology and neurological disorders act as major nodes of redirection, serving both as frequent endpoints and as mechanistic sources for cross-domain translation. The mean interval between first approval and repurposing is 7.2 years, shorter than typical development timelines for newly originated drugs. Repurposing occurs more rapidly when development rights remain with the original owner, and large firms account for most approvals.
Conclusions
Repurposing has become a durable component of pharmaceutical innovation, enabling faster clinical deployment of validated mechanisms across disease domains. These findings highlight its potential to expand treatment options while reducing R&D uncertainty.
Plain language summary
Drug repurposing occurs when a medicine already approved for one disease later gains approval for a different therapeutic use. Because developing entirely new treatments is lengthy and complex, repurposing can offer a faster and more reliable route to bring effective therapies to patients. In this study, we analyzed all FDA drug approvals over the past forty years to understand how repurposing actually unfolds. We traced how medicines move across disease areas, how long these transitions take, and how often companies redirect their own products compared with external developers.
Our findings show that repurposing is a stable and meaningful part of pharmaceutical innovation, enabling established scientific knowledge to be reapplied in new ways and accelerating the arrival of new treatment options.
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Data availability
All data used in this study were generated by the authors through systematic extraction from FDA primary sources. Drugs@FDA is an online public database that provides access to FDA approval documents, product labels and regulatory histories and can be accessed at https://www.fda.gov/drugs/development-approval-process-drugs/drug-approvals-and-databases. The FDA Approved Drug Products database, commonly referred to as the Orange Book, is also publicly available online at https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm. The aggregated numerical data used to generate the figures in this article are provided in Supplementary Data 1. The complete curated dataset developed for this study is protected under an i-Depot registration and cannot be publicly disseminated due to intellectual property restrictions and ongoing research use. However, all methodological steps required to reproduce the dataset are fully described in the article and the supplementary materials, allowing reconstruction of the dataset from publicly accessible FDA sources.
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Conceptualization: S.A. and H.S.; Methodology: S.A. and X.N.; Data curation: S.A.; Formal analysis: S.A., X.N., and B.S.; Investigation: S.A.; Supervision: H.S.; Writing—riginal draft: S.A.; Writing—review and editing: S.A., X.N., B.S., and H.S.
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Akodad, S., Niu, X., Secades, B. et al. Impact of drug repurposing between 1985 and 2024 on pharmaceutical innovation. Commun Med (2026). https://doi.org/10.1038/s43856-025-01344-1
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DOI: https://doi.org/10.1038/s43856-025-01344-1
