Molnupiravir to treat COVID-19

Molnupiravir blocks viral replication by incorporating itself into the RNA of SARS-CoV-2 causing viral death. It’s 4 capsules BID for 5 days.....

As a pharmacist, you’ll hear buzz about molnupiravir (Lagevrio), the first oral antiviral to treat COVID-19, now that it’s under FDA review. Molnupiravir blocks viral replication by incorporating itself into the RNA of SARS-CoV-2 causing viral death. It’s 4 capsules BID for 5 days and seems well tolerated.

Preliminary evidence suggests molnupiravir may reduce risk of hospitalization in about 1 in 35 outpatients age 18 and older with mild to moderate COVID-19 who are at high risk of developing severe illness. This seems similar to injectable COVID-19 monoclonal antibodies or “mabs” (Regen-COV, etc) but there aren’t direct comparisons.

Consider molnupiravir downsides. It’s too soon to say if it works against variants, such as Omicron. And there’s a theoretical concern it may lead to more viral variants since it incorporates into viral RNA. Plus animal studies suggest molnupiravir may cause birth defects. Expect FDA to clarify use in pregnancy. Be ready to identify candidates for molnupiravir. This will likely include adults with a positive COVID-19 test who are at high risk of severe illness (age 65 or older, diabetes, BMI over 25, etc).

Expect patients to be eligible regardless of vaccination status. These criteria are similar to mabs, but patients must start molnupiravir within 5 days of symptoms versus 10 days with mabs. For now, continue to refer eligible high-risk patients for COVID-19 mabs. And plan to stick with mabs instead of molnupiravir for patients under age 18, in pregnancy, or for postexposure prophylaxis.

Don’t suggest combining molnupiravir with COVID-19 mabs due to lack of data. Reinforce that patients on either med still need to self-isolate. There’s no evidence yet on whether molnupiravir or mabs prevent spread of infection. Clarify that patients don’t currently have to pay for these medications. Continue to emphasize COVID-19 vaccination, molnupiravir is not a substitute. Patients can be vaccinated as soon as they stop isolation.

References

FDA (2021). U.S. Food and Drug Administration Center for Drug Evaluation and Research FDA Briefing Document Antimicrobial Drugs Advisory Committee Meeting. [online] Available at: https://www.fda.gov/media/154418/download.
Jayk Bernal A, Gomes da Silva MM, Musungaie DB, et al. Molnupiravir for Oral Treatment of Covid-19 in Nonhospitalized Patients. N Engl J Med. 2022;386(6):509-520.
FDA (2021). U.S. Food and Drug Administration Center for Drug Evaluation and Research Addendum to FDA Briefing Document Antimicrobial Drugs Advisory Committee Meeting. [online] Available at: https://www.fda.gov/media/154419/download.