New Delhi: In the race to produce an oral antiviral drug for the prevention of Covid-19 infection, Pfizer Inc has begun its trials for the drug among those who have been exposed to the virus. Other drugmakers including US-based Merck & Co Inc and Swiss pharmaceutical Roche Holding AG are trying to develop an easy-to-administer antiviral pill for Covid-19, according to Reuters.


What are trials focused on?


The mid-to-late-stage trials will be focused on testing Pfizer's drug, PF-07321332, in up to 2,660 healthy adult participants aged 18 and older. Such participants will belong to the same household and shown confirmed symptomatic Covid-19 infection.


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


One-third of patients in the trial will receive a placebo, while the remaining people will be given a dose of the drug twice a day for either five or 10 days. 


The drugmaker has also started another study of PF-07321332 in non-hospitalized, symptomatic adult patients. As of now, Gilead Sciences Inc's intravenous drug remdesivir is the only antiviral treatment approved for Covid-19 in the United States.


Merck and partner Ridgeback Biotherapeutics also 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-hospitalized patients to see if it reduces the risk of hospitalization or death.