FDA authorizes the first at-home pills from Pfizer to treat Covid-19
The FDA on Wednesday signed off on Pfizer’s Covid-19 pills, which are meant to help keep people out of the hospital.
The news comes at a crucial moment, as the Omicron variant has taken over Delta as the prominent strain in the US, and as monoclonal antibody infusions will likely be in very short supply as two of the three currently marketed are ineffective against Omicron.
Pfizer will see early supply constraints of their pills, which are made up of nirmatrelvir tablets and ritonavir tablets, co-packaged for oral use, meaning doctors will have to be very careful on how they’re doled out. And if Merck’s pill is authorized soon too, there may be more options, although there’s also a drastic difference in efficacy between the two.
“I don’t think you would find anyone who would prefer the Merck pill to the Pfizer pill, given the data evident so far,” Walid Gellad, a professor of medicine at the University of Pittsburgh, told Endpoints News.
Merck’s pill saw its efficacy plummet between interim and final analyses in its pivotal trial — from a 50% relative reduction in hospitalizations and deaths at the interim to just 30% in the final results — meaning that more doctors will likely rely on the Pfizer pill. There are also questions about how Merck’s pill works, which led France’s experts to reject it.
Pfizer, meanwhile, recently said that its pill, known commercially as Paxlovid, proved to reduce the relative risk of hospitalization or death by 89% (within three days of symptom onset) and 88% (within five days of symptom onset) compared to placebo in a trial of more than 2,000 people.
The FDA also said in the EUA’s health care provider fact sheet that the pill should stand up against the Omicron variant, but the FDA did not review the pill before an adcomm so most of the trial data has only been released in Pfizer press releases so far. And all patients in the Pfizer trial had not received a Covid-19 vaccine.
Gellad warned that the “benefit of the pills definitely goes down in vaccinated people, and the magnitude of that reduction in benefit is still not clear. We only got preliminary data in the press release about impact on high-risk vaccinated people in the non-completed trial. There will be some benefit, but presumably not nearly the impact as on unvaccinated.”
The Pfizer pill is authorized for those over 12 years of age, weighing at least 88 pounds, with positive results of direct SARS-CoV-2 testing, and who are at high risk for progression to severe Covid, including hospitalization or death. But there are certain restrictions, with FDA saying Paxlovid is not recommended in patients with severe kidney or severe liver impairment, adding:
Because Paxlovid works, in part, by inhibiting a group of enzymes that break down certain drugs, Paxlovid is contraindicated with certain drugs that are highly dependent on those enzymes for metabolism and for which elevated concentrations of certain drugs are associated with serious and/or life-threatening reactions. Paxlovid is also contraindicated with drugs that, conversely, strongly induce those same enzymes, leading to the faster breakdown of nirmatrelvir or ritonavir, as reduced concentrations of nirmatrelvir or ritonavir may be associated with potentially losing virologic response and developing viral resistance. Paxlovid cannot be started immediately after discontinuing such medications because the effects of those medications remain after discontinuation.
But with very limited supplies initially (65,000 courses are shipping the first week of January), only a handful of states will see more than 3,000 courses of Paxlovid in that first week next month.
“An additional 200,000 courses are expected in January, ramping up steadily in the months ahead,” HHS said of Pfizer’s pill. The US has bought 10 million courses, and Pfizer said in a statement that it also raised production projections from 80 million to 120 million courses of treatment in 2022, as a result of continued investments.
The US also may have about 400,000 courses of Merck’s pill available in the next few days, if authorized, according to a Bloomberg report. But by the end of January, the US government expects to have about 3 million courses of Merck’s pill.
Also by the end of January, the US will have about 300,000 courses of the GlaxoSmithKline and Vir mAb treatment, and another 55,000 doses were shipped out this week.