Viagra's accidental repurposing

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GLP-1 drugs like Ozempic and Mounjaro have transformed the treatment of obesity as well as diabetes, can help treat heart disease, kidney disease, sleep apnea, and maybe even Alzheimer’s. But they are far from the only medicine with more than one use. Aspirin, colchicine, minoxidil, and Viagra were all found to treat more conditions than expected, and about a third of drugs end up with a second approved use.

In this episode, Jacob and Saloni explore the idea of drug repurposing: taking a medicine made for one disease and finding it works against others. They trace how GLP-1 drugs emerged from an adorable Gila monster, why some drugs have multiple uses, why so many of those uses go untested, and how patents, competition, prizes, and platform trials shape whether we ever find them.

Hard Drugs is a podcast from Works in Progress about medical innovation presented by Saloni Dattani and Jacob Trefethen.

You can watch or listen on YouTube, Spotify, or Apple Podcasts.

Saloni’s substack newsletter: https://www.scientificdiscovery.dev/

Jacob’s blog: https://blog.jacobtrefethen.com/ 

Acknowledgements:

• Aria Babu, editor at Works in Progress
• Graham Bessellieu, video editor
• Abhishaike Mahajan, cover art
• Atalanta Arden-Miller, art direction
• David Hackett, composer

Blogs

• Julia Rohrer (2018). The uncanny mountain: p-values between .01 and .10 are still a problem https://www.the100.ci/2018/02/15/the-uncanny-mountain-p-values-between-01-and-10-are-still-a-problem/ 
• Abhishaike Mahajan (2025). Mapping the off-target effects of every FDA-approved drug in existence (EvE Bio) https://www.owlposting.com/p/mapping-the-off-target-effects-of 

Videos

• George Davey Smith (2026). Does the shingles vaccine prevent dementia? https://www.youtube.com/watch?v=qlTnnQytOJ0 

Articles & report

• Radwan Darwish et al. (2025). History of glucagon-like peptide-1 receptor agonists. https://doi.org/10.1016/j.phrs.2025.108045 
• Brian L. Furman (2012). The development of Byetta (exenatide) from the venom of the Gila monster as an anti-diabetic agent. https://doi.org/10.1016/j.toxicon.2010.12.016 
• Eric Budish, Maya M. Durvasula, Benjamin N. Roin, Heidi L. Williams (2026). Missing markets for innovation: evidence from new uses for existing drugs. NBER Working paper. https://www.nber.org/system/files/working_papers/w34222/w34222.pdf 
• Babak Sahragardjoonegani, Reed F Beall, Aaron S Kesselheim, Aidan Hollis (2021). Repurposing existing drugs for new uses: a cohort study of the frequency of FDA-granted new indication exclusivities since 1997. https://pmc.ncbi.nlm.nih.gov/articles/PMC7780607/ 
• BMJ (2020). Covid-19: The inside story of the RECOVERY trial https://www.bmj.com/content/370/bmj.m2670 
• Stephan Guyenet (2021). The future of weight loss https://worksinprogress.co/issue/the-future-of-weight-loss/ 
• Kevin Hickey, Erin Ward (2024). The Role of Patents and Regulatory Exclusivities in Drug Pricing https://www.congress.gov/crs-product/R46679 
• Alex Kesin (2025). The three-thousand-year journey of colchicine https://worksinprogress.co/issue/the-three-thousand-year-journey-of-colchicine/ 
• Samy Suissa, Laurent Azoulay (2012). Metformin and the risk of cancer: time-related biases in observational studies https://doi.org/10.2337/dc12-0788 
• Nicholas Reville (2026). Proposing an NIH High-Leverage Trials (HILT) Program. Center for Addiction Science, Policy, and Research (CASPR) https://caspr.org/policy/papers/HILT/ 

Web

• Smithsonian’s National Zoo. Gila monster. https://nationalzoo.si.edu/animals/gila-monster