The Food and Drug Administration announcement on Merck’s molnupiravir comes one day after the agency cleared a competing drug from Pfizer.
Pfizer’s pill, Paxlovid, is likely to become the first-choice treatment against the virus, because of its superior benefits and milder side effects.
As a result, Merck’s pill is expected to have a lesser role against the pandemic than predicted just a few weeks ago. Its ability to head off severe COVID-19 is much smaller than initially announced and the drug label will warn of serious safety issues, including the potential for birth defects.
Both treatments will be free to patients in the U.S. after being purchased by the federal government.
The FDA authorized Merck’s drug for adults with a positive COVID-19 test, early symptoms and who face the highest risks of hospitalization, including older people and those with conditions like obesity and heart disease.
The agency said molnupiravir should be considered for patients “for whom alternative COVID-19 treatment options authorized by the FDA are not accessible or clinically appropriate.” It did not include that restriction for Paxlovid, which was authorized for patients 12 and older.
Molnupiravir, made by Merck and Ridgeback Biotherapeutics, also will carry a warning against use during pregnancy. Women of childbearing age should use birth control during treatment and for a few days after while men should use birth control for at least three months after their final dose, the FDA said. The federal agency also said molnupiravir should not be used in patients under age 18 because it may affect bone growth.
Dr. Nick Kartsonis, Merck’s senior vice president of clinical research, said company scientists are still studying the drug and they hope to eventually get it approved for use in children.
The restrictions were expected after an FDA advisory panel only narrowly endorsed the drug last month, warning that its use would have to be strictly tailored to patients who can benefit the most.
Kartsonis said Merck researchers are “very comfortable” with their drug’s safety profile.
He also noted that molnupiravir has been studied in more than a thousand people, and researches saw side effects like diarrhea and nausea in only a small percentage of patients.
“The drug has actually looked very well tolerated,” he said.
Pfizer’s Paxlovid also comes with limitations. Regulators say doctors have to consider how it will interact with other medicines a patient may be taking, and they’ve noted it shouldn’t be prescribed to patients with severe liver or kidney problems.
Both treatments also should be started within five days of the beginning of symptoms, a deadline that puts pressure on patients to get tested and diagnosed quickly.
The two pills work differently and Pfizer’s doesn’t carry the same risks. Additionally, Pfizer’s drug was roughly three times more effective in testing, reducing hospitalization and death by nearly 90% among high-risk patients, compared with 30% for Merck’s.
Some experts question whether there will be much of a role for the Merck drug in …….