U.S. regulators cleared the use of a Covid-19 pill from Merck and partner Ridgeback Biotherapeutics LP, the latest easy-to-use therapy that infected people can take to keep out of the hospital.
The authorization by the U.S. Food and Drug Administration permits doctors to prescribe the drug, called molnupiravir, to adults at high risk of severe disease shortly after they develop mild to moderate symptoms. There shouldn’t be an alternative authorized Covid-19 treatment that would be appropriate for the adults to take, the FDA said.
The thumbs-up comes after the FDA cleared another pill that people could take at home to try to stay out of the hospital, Paxlovid from Pfizer Inc.
Merck’s drug was found to be 30% effective in reducing the risk of hospitalization and death in a key study, while Pfizer said Paxlovid was 89% effective at reducing the risk of hospitalization and death in a key study. Both drugs were tested before the Omicron variant emerged.
The addition of the pills may bolster the fight against Omicron as it hurtles around the U.S. Researchers have said they expect the drugs to work against the new strain, though they are waiting for study results.
With a molnupiravir prescription, adults would take eight pills daily for five days, starting within five days of showing symptoms. The FDA didn’t authorize use among people who are hospitalized or under the age of 18.
The drug is expected to be available in the coming days in pharmacies, doctors’ offices, and other locations. Initial supplies will be limited, though Merck says it is ramping up manufacturing.
Citing the strong results for Pfizer’s drug, Wall Street analysts have scaled back sales estimates for molnupiravir and said they expect demand for the drug to be limited. Analysts expect Merck’s drug won’t sell nearly as much as Pfizer’s.
Until the FDA’s recent moves, there hadn’t been an antiviral like Paxlovid or molnupiravir cleared to reduce the risk of hospitalization in adults with the virus. Another kind of therapy, known as an antibody-drug, has been in use to prevent severe disease.
Yet the antibody treatments are expensive to administer, can be tough to find in rural areas, and are primarily administered at physician clinics or hospitals and given via injections or infusions.
Given the drawbacks, doctors and health authorities have been looking for a pill that people could easily take at home to try to avoid hospitalization.
Also, several of the antibody drugs don’t appear to work well against Omicron, prompting some hospitals to halt their use given the variant’s spread.
Anticipation for molnupiravir grew when the companies reported that a preliminary analysis of study results found the drug 50% effective. Yet the excitement was tempered after a final analysis found the drug efficacy was lower.
Some health experts have also raised safety concerns and whether molnupiravir might cause mutations in cells that are harmful to people. Merck and Ridgeback have said the drug is safe, and testing in humans found it didn’t cause mutations.
The FDA has said its own review of the companies’ data found no major safety concerns in late-stage testing. The FDA also found the treatment presented a low risk of mutation, known as mutagenicity.
Molnupiravir targets a different part of the virus than the spike protein that vaccines and other treatments focus on. The drug targets machinery the virus uses to replicate, rather than the spike protein, the structure that helps the virus infiltrate cells. Pfizer’s Paxlovid doesn’t target the spike protein either and works differently than other Covid-19 vaccines and drugs.
Merck has said it plans to study whether molnupiravir is effective against the variant but it has presented data showing how the drug is effective against other variants and expects similar results with Omicron.
Omicron has several mutations to the spike protein, which researchers say could help the variant evade vaccines and drugs trained on that part of the virus.
Merck, based in Kenilworth, N.J., has agreed to provide the U.S. government with 3.1 million courses of the drug for about $2.2 billion.
The company has said it expects to distribute molnupiravir shortly after the authorization, but the timing depends on how fast it can ready the packaging and prescribing information, which is determined by the FDA.
In November, an outside panel of scientific advisers to the FDA narrowly recommended the agency authorize molnupiravir.
Panel members who voted against the recommendation said they were concerned with how there wasn’t a clear explanation on why molnupiravir’s efficacy changed and that the drug’s benefit to patients may be minimal.
Some also said they were concerned the drug could cause mutations in human cells and that more study of the drug is needed to assess that possibility.
The U.K. cleared molnupiravir for use in November.
To try to make molnupiravir more readily available to people in low- and middle-income countries, Merck has licensed out the drug to the United Nations-backed Medicines Patent Pool and generic drugmakers.
Despite such efforts, some drug-access advocates and public-health experts say that molnupiravir and Pfizer’s antiviral are likely to take longer to reach poorer countries because of manufacturing and pricing obstacles.