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# FDA Approves Smallpox Drug
- URL: https://www.fdaweb.com/fda-approves-smallpox-drug/
- Published: 2021-06-04T12:00:00.000Z
- Updated: 2026-09-14T17:01:49.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5149473

FDA has approved a Chimerix NDA for Tembexa (brincidofovir) for treating smallpox. “Although naturally occurring smallpox no longer exists, concerns about potential uses of variola virus as a bioweapon has made smallpox drug development an important component of the U.S. medical countermeasures response,” an [FDA release](https://u7061146.ct.sendgrid.net/ls/click?upn=4tNED-2FM8iDZJQyQ53jATUURzbOiTj4rjf8eQ-2FYEfOQ5THSul0bFGo4FhyR4b-2BPkN6tXfIb03jEQfD9nEWL3f9zp6qTLQ1TnQtywumfiKIWTfsqz1eo-2FJuT92HVTN-2FERDegvk6o8O-2BRg0ev6CJDN6sqUPjpwgJqqskgkR3ylXLf-2FhWSpSwNKnJ2NwurfZJCEHlOIKL-2FwRXQvfC4w-2FyQdRZAfA-2FoUrLqaXSXZ525u8JRBaWbgZnTMDAYDOOaijklDrhyhWIGSL5mczbyatq7AnzYna7zevEH-2FoVZy-2BOePq76IJjmtnTQq9h4p4paAtzoFyADcM-2BsdgZESlCxdo8B4JCZEkd8XD20nJyOfClokRKZQWt1mFlXMjHrkcsfWHUzwRMqra-2B22nJvTs2fZcyMdtkDxFRF3Uy0N35o3OAXNrzCypfyCyJIHz3hIlhTiRPbAB9CnA%5Ff0D7hj0BJ4b-2F7NuVqzPDs7FGiq8VLIwAX0sPSotqoLIZH-2BlHUpIN1Fpx16wXLzBItZQB-2B865N-2BRM-2FfR3UV9b-2BzD8pZSEDjr63FamAR-2FX-2BMXNOEC58BP6EXAw5Nxp5nMrxHbHZO3cSJB56nFfojV8euVIUPTEvLZJml4O6aOS3NT0SK4UJvULcDAMVJ9ZHpYHkpfpIi471m2TdCGKXK35jz6uuiu88Pn8nBfZGXUmGlimfQxgOIB8WYJzTnU5jGGGL4cV-2BgEXK4hSdY9WYTzEbm2yafjISMtxh3q9FHDlJr-2FOx2mbdVE-2FB6YS1OgbkEU9ZfPl2O0REkZaPgwHIFDrBQ-3D-3D&ref=fdaweb.com) says.  

Because smallpox was eradicated in 1980, Tembexa was studied in animals infected with viruses that are closely related to the variola virus. More animals treated with Tembexa survived compared to the animals treated with placebo, the agency says. “Safety information to support approval of Tembexa was derived from clinical trials of the drug for a non-smallpox indication, primarily from patients who received hematopoietic stem cell transplants,” it says. “An increased risk of death was seen in another disease (Cytomegalovirus disease — a viral infection) when Tembexa was used for a longer-than-recommended duration (longer than once a week for two weeks on days 1 and 8).”The most common side effects are diarrhea, nausea, vomiting, and abdominal pain.