Pfizer’s Paxlovid Becomes First Oral COVID Antiviral Drug to Receive US FDA EUA

By HospiMedica International staff writers
Posted on 24 Dec 2021

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Pfizer Inc.’s (New York, NY, USA) PAXLOVID (nirmatrelvir [PF-07321332] tablets and ritonavir tablets) has been authorized for emergency use by the US Food and Drug Administration (FDA) for the treatment of mild-to-moderate COVID-19 in adults and pediatric patients (12 years of age and older weighing at least 40 kg [88 lbs]) with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progression to severe COVID-19, including hospitalization or death.

The 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 based its decision on clinical data from the Phase 2/3 EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients) 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 to placebo, within three days of symptom onset (primary endpoint). No deaths occurred in the treatment group compared to nine deaths in the placebo group by Day 28.

Similar results were seen in those treated within five days of symptom onset (secondary endpoint), with an 88% reduction in risk and no deaths observed in the treatment group. Treatment-emergent adverse events were comparable between PAXLOVID (23%) and placebo (24%), most of which were mild in intensity. While PAXLOVID clinical trials did not include patients under the age of 18, the authorized adult dosing regimen is expected to result in comparable blood concentration levels of PAXLOVID in pediatric patients 12 years of age and older weighing at least 40 kg. Additional Phase 2/3 clinical trials are ongoing 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. In addition to the US FDA EUA, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has also issued advice that PAXLOVID can be used to treat adults with COVID-19 who do not require supplemental oxygen and who are at increased risk of progressing to 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. 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,” said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. “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.”

“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,” said Patrizia Cavazzoni, M.D., director of the FDA’s Center for Drug Evaluation and Research. “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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