FDA authorizes Pfizer’s Covid treatment pill (the first oral antiviral drug cleared during the pandemic)

 

Merck’s experimental Covid-19 treatment pill, called molnupiravir

The Food and Drug Administration granted emergency authorization Wednesday to Pfizer’s Covid treatment pill, a major milestone that promises to revolutionize the fight against the virus.

The medication, which is recommended for people at a high risk of developing severe Covid-19, could be available to patients as early as this weekend. Pfizer CEO Albert Bourla told the press earlier this month the company has already shipped some of the pills to the U.S. so they can be prescribed as soon as the FDA authorization comes through. The Centers for Disease Control and Prevention is expected to quickly follow suit with its seal of approval, authorizing its distribution.

The FDA cleared the pill for patients 12 and up with mild to moderate Covid who are most likely to end up hospitalized or not survive. The agency said it should be prescribed as soon as possible after diagnosis and within five days of symptom onset.

“Today’s authorization introduces the first treatment for COVID-19 that is in the form of a pill that is taken orally — a major step forward in the fight against this global pandemic,” Dr. Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research, said in a statement. “This authorization provides a new tool to combat COVID-19 at a crucial time in the pandemic as new variants emerge and promises to make antiviral treatment more accessible to patients who are at high risk for progression to severe COVID-19.”

Pfizer’s pill is the first oral antiviral drug authorized by the FDA that is specifically designed to fight Covid. The authorization comes at a crucial turning point in the pandemic, as hospital systems across the U.S. have been battered by a wave of delta infections, and are now bracing for another wave of patients infected with the highly contagious omicron variant.

Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia and an FDA advisor, said that the development is good news, but immunizing unvaccinated people remains the ultimate goal.

“Would you be more likely to take this drug than you would to get a vaccine? I think the answer to that question is yes,” Offit said in a phone interview. “So therefore it is of value for those 40 million, 50 million people in this country who simply refuse to be vaccinated. I mean, this may keep them out of the hospital.”

The U.S. has purchased 10 million courses of Pfizer’s treatment, Paxlovid, in a $5 billion deal. President Joe Biden said in November that his administration is working to ensure that the treatments are free and accessible. Biden said last month that delivery would start by the new year and continue through 2022.

Merck has contracted with the U.S. government to supply at least 3 million courses of its pill, molnupiravir, which is still awaiting clearance, for $2.2 billion. The FDA declined to comment on Merck’s drug.

Pfizer’s treatment is administered in two 150 milligram tablets along with a 100 milligram tablet of an HIV drug, ritonavir, twice daily. The HIV drug helps slow the patient’s metabolism, which allows Paxlovid to remain active in the body at a higher concentration for a longer period.

Merck’s 800 milligram pill is taken every 12 hours for five days after symptom onset. The drug was developed with Ridgeback Biotherapeutics.

Bourla has said he expects Paxlovid to remain highly effective at treating people infected with the omicron variant. The pill targets an enzyme the virus needs to replicate. Bourla said it is very hard for the virus to mutate in a way where it doesn’t need the enzyme, called a protease.

“It’s very difficult for the virus to create a strain that can live without this protease,” Bourla told The Wall Street Journal during an interview at a conference earlier this month. “It’s not impossible. It’s very difficult.”

Molnupiravir prompts the virus to mutate and produce errors that inhibit its ability to replicate, Merck said.

“Even if the probability is very low, 1 in 10,000 or 100,000, that this drug would induce an escape mutant from which the vaccines we have do not cover, that could be catastrophic for the whole world actually,” Dr. James Hildreth, CEO of Meharry Medical College in Nashville, Tennessee, told the panel the FDA panel in November.

Panel members also grappled with whether or not pregnant women should take the pill in limited circumstances when they have severe Covid. Molnupiravir induced birth defects in animal studies. Merck never intended pregnant women to use the pill and did not include them in clinical trials.