Today, the FDA authorized the emergency use of the first at-home, oral pill for the treatment of mild-to-moderate COVID-19. The pill, PAXLOVID, was designed by Pfizer for patients 12 years and older who are at high risk for progression to severe COVID-19, including hospitalization and death. While the timing might make it seem like a holiday miracle, scientists and researchers at Pfizer have been working on this treatment option since the pandemic began.
“Today’s authorization of PAXLOVID represents another tremendous example of how science will help us ultimately defeat this pandemic, which, even two years in, continues to disrupt and devastate lives across the world,” said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. “This breakthrough therapy will change the way we treat COVID-19, and hopefully help reduce some of the significant pressures facing our healthcare and hospital systems.”
The antiviral pill treatment includes nirmatrelvir, a novel main protease (Mpro) inhibitor originating in Pfizer’s laboratories, which was specifically designed to block the activity of the SARS-CoV-2 Mpro, an enzyme that the coronavirus needs to replicate.
The FDA’s EUA authorization was based on data from the Phase 2/3 EPIC-HR clinical trial, which enrolled non-hospitalized adults aged 18 and older with confirmed COVID-19 who are at increased risk of progressing to severe illness.
The data demonstrated an 89% reduction in the risk of COVID-19-related hospitalization or death from any cause in adults treated with PAXLOVID, compared with placebo, when the pill was administered within three days of symptom onset.
No deaths occurred in the treatment group compared with nine deaths in the placebo group by Day 28.
Similar results were seen in those treated within five days of symptom onset, with an 88% reduction in risk and no deaths in the treatment group.
Clinical trial data indicates the side effects were all mild, and comparable between the PAXLOVID (23%) and placebo (24%) groups.
Unlike the vaccines, PAXLOVID's efficacy is not affected by variants of concern. Rather than inhibit the spike protein, PAXLOVID works intracellularly by binding to the protease of the SARS-CoV-2 virus to inhibit viral replication. According to Pfizer, nirmatrelvir has shown consistent in vitro antiviral activity against current variants, including alpha, beta, delta, gamma, lambda and mu.
The pharmaceutical company says nirmatrelvir potently inhibited the Mpro associated with Omicron in an in vitro biochemical assay, but additional studies with this new variant are necessary and underway.
Pfizer will also continue Phase 2/3 clinical trials for PAXLOVID in adults at standard risk (i.e., low risk of hospitalization or death) of progressing to severe illness, and in those who have been exposed to the virus through household contacts.
PAXLOVID is authorized to be administered at a dose of 300 mg (two 150 mg tablets) of nirmatrelvir with one 100 mg tablet of ritonavir, given twice-daily for five days.
With the EUA in place, Pfizer says it is ready to start immediate delivery in the U.S. On November 18, the pharmaceutical giant and the U.S. government reached a $5.29 billion agreement for 10 million treatment courses of the pill, starting with immediate delivery if/when it was authorized all the way through 2022.
At the time, Pfizer projected it could produce 80 million courses through the new year; however, on the heels of the EUA, the pharma company has increased that projection to 120 million courses “as a result of continued investments to support the manufacturing and distribution of PAXLOVID.”
Pfizer has also entered into advance purchase agreements with several other countries and has initiated bilateral outreach to approximately 100 countries around the world.
Pfizer company plans to file a New Drug Application with the FDA for full regulatory approval in 2022.