Paxlovid

Paxlovid is an oral antiviral treatment for non-hospitalized patients with mild-to-moderate COVID-19 who are at high risk of progression. It consists of two co-packaged drugs, nirmatrelvir and ritonavir, and is taken as a five-day course.

Nirmatrelvir inhibits the SARS-CoV-2 main protease 3CLpro, blocking viral replication. Ritonavir acts as a pharmacokinetic booster by inhibiting CYP3A-mediated metabolism, increasing nirmatrelvir levels.

The standard dose is 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one tablet) taken together every 12 hours for five days. For patients with CrCl 30–59 mL/min, the dose is reduced to 150 mg nirmatrelvir with 100 mg ritonavir every 12 hours for five days. It is not recommended for patients with CrCl below 30 mL/min. Treatment should be started as soon as possible after symptom onset, ideally within five days.

Because ritonavir inhibits CYP3A and other metabolic pathways, Paxlovid has potential interactions with many medicines, including some statins, antiarrhythmics, anticoagulants, and immunosuppressants. A clinician should review current medications before starting treatment. Common adverse events include dysgeusia (altered taste), diarrhea, and vomiting; liver function may be monitored in some patients; rare cases of viral rebound after treatment have been reported.

Paxlovid has been approved or authorized for emergency use in multiple regions for high-risk non-hospitalized patients, and is not indicated for those who require hospitalization for severe COVID-19. Treatment is typically started early in the disease course to reduce the risk of progression.