FDA Gives OK to Merck Antiviral At-Home COVID-19 Pill

Many Americans now have two oral antiviral pills that can be taken at home to treat a fresh case of COVID-19. The U.S. Food and Drug Administration on Thursday approved the emergency use of the molnupiravir pill from Merck for the treatment of mild-to-moderate COVID-19 in people who have just tested positive.

The approval comes on the heels of Wednesday's approval of the Pfizer COVID-19 antiviral pill Paxlovid. Both pills are intended only for people who are at high risk for hospitalization and death from severe COVID-19, and they are available by prescription only.

But the two pills are not interchangeable: The Pfizer drug far outperformed the Merck drug in clinical trials. While molnupiravir cut the risk for hospitalization and death in high-risk patients by 30 percent, Paxlovid did so by nearly 90 percent. Molnupiravir works by introducing errors into the genetic code of the the coronavirus, which first hampers and then prevents the virus from replicating.

COVID-19 patients would take four 200-mg capsules at a time every 12 hours for five days, for a total of 40 capsules, the FDA said. As with Paxlovid, patients should start their pill regimen as soon as possible after their COVID-19 diagnosis and within five days of symptom onset, according to the FDA. Molnupiravir is not authorized to be taken to prevent COVID-19 infection in people who have been exposed to a sick person, the FDA noted. It also cannot be taken by patients who are so sick they have been hospitalized. The FDA warned that the two antiviral pills should not be considered a substitute for vaccination.

Emergency approval of molnupiravir was supported by a clinical trial comparing 709 COVID-19 patients who got the drug to 699 patients who received a placebo. About 6.8 percent of people who got molnupiravir were hospitalized or died during a month of follow-up compared with 9.7 percent of people who received a placebo, the FDA said. That includes one patient given molnupiravir who died compared with nine placebo patients who died.

Side effects observed in the clinical trial included diarrhea, nausea, and dizziness. Molnupiravir is not authorized for patients younger than 18 years because it might affect bone and cartilage growth. It is also not recommended for use during pregnancy, because animal studies showed that the drug may cause fetal harm.