FDA Authorizes First Oral COVID Antiviral Drug
The U.S. Food and Drug Administration (FDA) granted Emergency Use Authorization (EUA) to Pfizer’s Paxlovid (nirmatrelvir and ritonavir tablets) for high-risk adults and pediatric patients 12 years and older to treat COVID-19. The EUA is for patients at high risk of progression to severe COVID-19, which includes hospitalization or death.
On December 14, Pfizer reported final data from the Phase II/III EPIC-HR trial of Paxlovid, which was consistent with an interim data analysis from November. Paxlovid significantly reduced the risk of hospitalization or death by 89% compared to placebo in non-hospitalized, high-risk adults with COVID-19 within three days of symptom onset. They also studied it in patients receiving the drug within five days of symptoms, and it decreased risk of hospitalization or death for any cause by 88% compared to placebo.
Of particular importance is that this is an oral antiviral candidate. For example, Gilead Sciences’ Veklury (remdesivir), the first drug authorized and approved to treat COVID-19, is an infusion that has to be dosed within a clinic or hospital setting. Paxlovid can be taken at home. Each pack contains 30 tablets to be taken over five days.
Paxlovid is made up of two antiviral drugs, nirmatrelvir, a novel main protease inhibitor developed by Pfizer and specifically engineered to block the activity of the main protease of SARS-CoV-2. Ritonavir is an HIV drug sold under the brand name Norvir.
Pfizer says they’re prepared to begin distribution of the drug immediately. In November, the company inked a deal with the U.S. government to supply 10 million treatment courses of the antiviral cocktail, with fulfillment expected to be completed in 2022.
The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) advised on December 16 that Paxlovid could be used for adults with COVID-19 who don’t require supplemental oxygen but are at increased risk of severe disease.
“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 of Pfizer. “This breakthrough therapy, which has been shown to significantly reduce hospitalizations and deaths and can be taken at home, will change the way we treat COVID-19, and hopefully help reduce some of the significant pressures facing our healthcare and hospital systems. Pfizer stands ready to begin delivery in the U.S. immediately to help get Paxlovid into the hands of appropriate patients as quickly as possible.”
The FDA is also evaluating an antiviral pill from Merck and Ridgeback Biotherapeutics, molnupiravir, which is expected to be authorized soon. In late November, the FDA’s Antimicrobial Drugs Advisory Committee voted 13 to 10 to recommend EUA for molnupiravir. Results from clinical trials suggested molnupiravir offered a relative risk reduction of 30%. It has already been authorized in the UK. Molnupiravir is an oral form of a potent ribonucleoside analogist that inhibits the replication of SARS-CoV-2.
Of the Pfizer EUA, Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research, stated that the pill was a “major step forward,” adding that, “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.”
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