Nov 30 Reuters -- A panel of expert advisers to the U.S. Food and Drug Administration will vote later on Tuesday on whether to approve Merck Co's antiviral pill to treat COVID - 19.
The U.S. drugmaker reported on Friday that the oral medicine's efficacy in reducing hospitalizations and deaths had dropped to 30% with data available from over 1,400 patients in its late-stage study. It had reported a 50% reduction using data from 775 patients a month ago.
As medicines like Merck's molnupiravir developed with Ridgeback Biotherapeutics and Pfizer's Paxlovid become important therapeutic tools that can be taken at home as soon as COVID 19 symptoms occur, analysts said they still expect the drug to be approved.
The rival oral therapies target parts of the virus that are not changed by mutations in the new Omicron variant. They could become even more vital if vaccine-induced and natural immunity are threatened by the variant.
The Merck pills are meant to be taken twice a day for five days after the onset of COVID- 19 symptoms.
The FDA's staff, in briefings posted ahead of the meeting of outside experts, did not make a recommendation on whether the drug should be authorized, but they said they would provide their assessment of the new data at the meeting.
They raised concerns over whether the drug could cause the virus to mutate, and asked the panel to discuss if a more targeted population of patients could be offered the medicine to mitigate those concerns.
In animal studies, drugs in the same class as molnupiravir have been linked to birth defects. Merck has said similar studies of molnupiravir -- for longer and at higher doses than in humans -- indicate that the drug does not affect mammalian DNA.
The Mizuho analyst Vamil Divan said that there were significant discussions on molnupiravir's mechanism of action, as well as theoretical safety concerns, especially related to potential birth defects from the drug, and whether the drug should be used in pregnant women or women of childbearing age.
More countries may sign deals for the Pfizer drug, taken with another antiviral, ritonavir, showing an 89% reduction in hospitalizations and deaths in a trial, Divan said.
Pfizer's trial, like Merck's, was stopped early due to its high success rate.