Nirmatrelvir/ritonavir

Nirmatrelvir/ritonavir, sold under the brand name Paxlovid, is a co-packaged medication used as a treatment for COVID‑19. It contains the antiviral medications nirmatrelvir and ritonavir and was developed by Pfizer. Nirmatrelvir inhibits SARS-CoV-2 main protease, while ritonavir is a strong CYP3A inhibitor, slowing down nirmatrelvir metabolism and therefore boosting its effect. It is taken by mouth.

In unvaccinated high-risk people with COVID‑19, nirmatrelvir/ritonavir can reduce the risk of hospitalization or death by 88% if taken within five days of symptom onset. People who take nirmatrelvir/ritonavir also test negative for COVID‑19 about two and a half days earlier than people who do not. Side effects of nirmatrelvir/ritonavir include changes in sense of taste (dysgeusia), diarrhea, high blood pressure (hypertension), and muscle pain (myalgia).

In December 2021, the United States Food and Drug Administration (FDA) granted nirmatrelvir/ritonavir emergency use authorization (EUA) to treat COVID‑19. It was approved in the United Kingdom later that month, and in the European Union and Canada in January 2022. In May 2023, it was approved in the US to treat mild to moderate COVID‑19 in adults who are at high risk for progression to severe COVID‑19, including hospitalization or death. The FDA considers the combination to be a first-in-class medication. In 2022, it was the 164th most commonly prescribed medication in the United States, with more than 3 million prescriptions.