The company and its rivals, including U.S.-based Merck & Co and Swiss pharmaceutical Roche Holding AG, have been racing to develop the first antiviral pill to be taken upon early signs of the illness.
Pfizer’s mid-to-late-stage trial in 1,140 participants would study the therapy PF-07321332 in combination with a low dose of ritonavir, which has been used with other antivirals too, the company said.
PF-07321332 is a protease inhibitor, designed to block the activity of a key enzyme that is needed for the coronavirus to replicate.
To date, Gilead Sciences’ remdesivir, administered intravenously, is the only approved antiviral treatment for COVID-19 in the United States.
Merck and partner Ridgeback Biotherapeutics’ molnupiravir, an oral ribonucleoside, is already being studied in a late-stage trial in non-hospitalized patients to see if it reduces the risk of hospitalization or death.
The companies said Sept. 1 that they had also started a late-stage prophylaxis trial of molnupiravir for the prevention of COVID-19 infection among people exposed to a household member with symptomatic COVID-19.
Pfizer said in July if the PF-07321332 trial was successful, it would file for a potential emergency use authorization in the fourth quarter.
Reuters Health Information © 2021