Pfizer begins early-stage study of oral COVID-19 drug

Pfizer Inc has started an early-stage U.S. trial of an oral COVID-19 antiviral therapy that could be prescribed to patients at the first sign of infection, the company said on Tuesday.

The drugmaker, which developed the first authorized COVID-19 vaccine in the U.S. with Germany’s BioNTech SA, said the antiviral candidate showed potent activity against SARS-CoV-2, the virus that causes COVID-19, in lab studies.

Pfizer’s candidate, named PF-07321332, is a protease inhibitor that prevents the virus from replicating in cells.

Protease inhibitors have been effective at treating other viral pathogens such as HIV and hepatitis C virus, both on their own and in combination with other antivirals, the company said.

Pfizer believes this class of molecules may provide well-tolerated treatments against COVID-19, as currently marketed therapeutics that work on the same lines have not reported safety concerns.

The company is also studying an intravenously administered antiviral candidate in an early-stage trial in hospitalized COVID-19 patients.