Federal health officials say an experimental COVID-19 pill from Merck is effective against the virus, but they will seek outside experts on the risks of birth defects and other potential problems during pregnancy.
The Food and Drug Administration released its analysis of the pill ahead of a public meeting next week where academic and other experts will weigh its safety and effectiveness. The agency is not obliged to follow the advice of the group.
FDA scientists said their review identified several potential risks, including potential toxicity to developing fetuses and birth defects found in animal studies with the pill.
Given these risks, the FDA will ask its advisors next Tuesday whether the drug should never be given during pregnancy or whether it could be made available in certain cases.
In that scenario, the FDA said the drug would contain warnings of risks during pregnancy, but doctors would still have the option to prescribe it in certain cases where the benefits might outweigh the risks to patients.
In light of the safety concerns, the FDA said Merck had agreed that the drug would not be used in children.
Other side effects were mild and rare, with about 2 percent of patients experiencing diarrhea.
Regulators also noted that, overall, Merck has collected far less safety data on its drug than it has on other COVID-19 therapies.
“Although the clinical safety database was small, no major safety concerns were identified,” the FDA reviewers concluded.
Additionally, the FDA has raised concerns that Merck’s drug caused small changes in the coronavirus’ characteristic spike protein that it uses to enter human cells. In theory, the FDA warned, these changes could lead to dangerous new variants.
The FDA will ask its independent advisors to discuss all of these issues and then vote on whether the overall benefits of the drug outweigh its risks.
All COVID-19 drugs currently approved by the FDA require an injection or IV and can only be administered by health care professionals. If approved, Merck’s drug would be the first drug US patients could take at home to relieve symptoms and speed recovery. In the UK it is already approved for emergencies
The meeting marks the first time regulators have publicly reviewed a new drug for COVID-19, reflecting intense interest and scrutiny on a pill that could soon be used by millions of Americans.
The drug molnupiravir has been shown to reduce hospital admissions and deaths in people with mild to moderate coronavirus infections.
Merck’s drug uses a novel approach to combating COVID-19: It inserts tiny mutations into the genetic code of the coronavirus to stop the virus from multiplying.
But this genetic effect has raised concerns that the drug could, on rare occasions, cause birth defects or even trigger more virulent strains of the virus.
Pregnant women were excluded from the Merck study, and both women and men in the study were instructed to use contraception or abstain from sex.
Merck says the results of two company studies in rodents show that the drug does not cause mutations or DNA damage at the doses studied.
FDA reviewers also confirmed previously reported interim results from Merck that the pill reduced hospitalization and death rates by about half in patients with early symptoms of COVID-19 who were at increased risk due to health problems.
However, on Friday morning, Merck announced updated results from the same study showing lesser benefit from the drug. The FDA said it is still reviewing the updated data and will come back with a new evaluation of the drug’s effectiveness next Tuesday.
Among more than 1,400 adults in a company study, molnupiravir reduced the combined risk of hospitalization and death by 30 percent, less than the 50 percent originally reported due to incomplete results.
Almost 7 percent of patients who received Merck’s drug within five days of symptoms of COVID-19 ended up in hospital and one died. That compared to 10 percent of hospitalized patients who took the placebo and nine deaths.
Merck has not tested its drug in people who were vaccinated against COVID-19. However, the FDA will ask advisors to recommend which patients could benefit most from the drug based on vaccination status and underlying health issues.
While Merck’s drug is likely to be the first anti-coronavirus pill in the United States, more are set to follow.
Competing drug maker Pfizer has submitted its own antiviral for FDA review after initial study results showed it reduced the combined rate of hospitalizations and deaths by nearly 90 percent.
Pfizer’s drug is part of a decade-old family of antiviral pills known as protease inhibitors that revolutionized the treatment of HIV and hepatitis C. They work differently from the Merck pill and have not been linked to the type of mutational concerns raised with Merck’s drug.
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