Pfizer begins study of oral drug for prevention of Covid-19

Pfizer Inc (PFE.N) said on Monday it has started a large study testing its investigational oral antiviral drug for the prevention of Covid-19 infection among those who have been exposed to the virus.

The drugmaker and its rivals, including US-based Merck & Co Inc (MRK.N) and Swiss pharmaceutical Roche Holding AG (ROG.S), have been racing to develop an easy-to-administer antiviral pill for Covid-19.

The mid-to-late-stage study will test Pfizer's drug, PF-07321332, in up to 2,660 healthy adult participants aged 18 and older who live in the same household as an individual with a confirmed symptomatic Covid-19 infection.

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In the trial, PF-07321332, designed to block the activity of a key enzyme needed for the coronavirus to multiply, will be administered along with a low dose of ritonavir, an older medication widely used in combination treatments for HIV infection.

To date, Gilead Sciences Inc's (GILD.O) intravenous drug remdesivir is the only approved antiviral treatment for Covid-19 in the United States.

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Pfizer has also started another study of PF-07321332 in non-hospitalised, symptomatic adult patients.

Merck and partner Ridgeback Biotherapeutics recently launched a late-stage trial of their experimental drug molnupiravir for prevention of the Covid-19 infection.

Molnupiravir is also being studied in a late-stage trial in non-hospitalised patients to see if it reduces the risk of hospitalisation or death.