US FDA authorizes Merck's at-home antiviral Covid-19 pill

The US Food and Drug Administration on Thursday authorized Merck & Co's antiviral pill for Covid-19 for certain high-risk adult patients, a day after giving the go-ahead to a similar treatment from Pfizer Inc for high-risk patients above the age of 12. 

Merck's drug, molnupiravir, developed with Ridgeback Biotherapeutics, was shown to reduce hospitalizations and deaths by around 30% in a clinical trial of high-risk individuals early in the course of the illness.

The agency authorized the oral drug for the treatment of mild-to-moderate Covid-19 in adults who are at risk for severe disease, and for whom alternative Covid-19 treatments are not accessible or clinically appropriate.

The decision follows a narrow vote in favor of authorization by a panel of advisers to the FDA on 30 November. 

Both the Merck and Pfizer pills could be promising tools for those who are sick with Covid-19, especially in the face of the fast-spreading Omicron variant, which is now dominant in the United States.

"As new variants of the virus continue to emerge, it is crucial to expand the country's arsenal of Covid-19 therapies using emergency use authorization," said Patrizia Cavazzoni, director of the FDA's Center for Drug Evaluation and Research.

The drug is not authorized for use in patients younger than 18 because molnupiravir may affect bone and cartilage growth, the FDA said. Pfizer's drug was authorized on Wednesday for people aged 12 and older.

Pfizer's antiviral regimen, Paxlovid, was nearly 90% effective in preventing hospitalizations and deaths in patients at high risk of severe illness, according to trial data.

The lower efficacy of Merck's drug compared with Pfizer's treatment could hurt future sales.

The US government's contract for 10 million courses of the Pfizer drug at a price of $530 per course compares to the deal with Merck for as many as 5 million courses of molnupiravir at a price of $700 per course.