The FDA has granted emergency use authorization to Merck’s antiviral drug to treat adults with mild to moderate COVID-19 who are at risk for severe disease.
Similar to FDA authorization of another antiviral pill regimen -- ritonavir plus nirmatrelvir, or Paxlovid -- granted to Pfizer on Wednesday, molnupiravir (brand name Lagevrio) should be taken early in the course of COVID-19 illness.
Pfizer’s drug is authorized for anyone age 12 and up. But Merck’s is only for adults ages 18 and older.
Merck filed an application for emergency use authorization with the FDA in October. The company included results of its phase III study showing the treatment could lead to a 50% reduction in COVID-19 hospitalizations. Data later showed this efficacy closer to a 30% reduction. In November, an FDA advisory panel narrowly recommended the agency grant authorization by a 13-10 vote.
Animal studies found the drug may harm a fetus, so it is not recommended for pregnant people, the FDA says. It may be prescribed to a pregnant person only after their doctor determines the benefits outweigh the risks and the patient is told of those risks.
Women who may get pregnant should use a reliable method of birth control if being treated with molnupiravir and for 4 days after the final dose.
Two Weapons Against COVID
Two antiviral pills could be better than one, at least in terms of making more COVID-19 treatments available in early 2022. It is yet to be seen if the drugmakers will be able to keep up with demand, which could substantially increase with an expected surge in Omicron variant cases.
Ritonavir and molnupiravir join remdesivir (brand name Veklury) as available antivirals to treat COVID-19. Remdesivir is fully approved by the FDA but is given only through an IV to people in the hospital.
Officials point out that COVID-19 treatments in tablet form are more convenient for patients in the U.S. and across the globe, particularly where IV infusion services may be limited.
In March 2021, experts accurately predicted that the molnupiravir pill would be available by year's end.
Interestingly, in September, Merck announced the findings of laboratory studies suggesting that molnupiravir would work against variants of SARS-CoV-2 because the agent does not target the virus's spike protein.
Perhaps in part because of early promising results, the U.S. government announced in November intentions to purchase $1 billion worth of molnupiravir. That new order came on top of $1.2 billion worth of the pills the U.S. ordered in June.