KENILWORTH, New Jersey — Merck announced a deal with five makers of generic drugs in India to produce molnupiravir, an experimental antiviral similar to the COVID-19 medicine remdesivir but in a more convenient pill form.

Late-stage testing of the drug just started in the United States, and it’s unclear when the medicine might be used in India or elsewhere. A mid-stage study gave encouraging results, suggesting the drug quickly reduced virus levels when used early after infection.

Remdesivir is widely used for certain hospitalized patients but must be given as an infusion, which limits its use.

Molnupiravir, a pill that Merck is developing with Ridgeback Biotherapeutics, has shown wide activity against many types of respiratory viruses, according to Dr. George Painter, an Emory University professor who helped discover it.

“It’s my assumption that those generic drug manufacturers who have enormous capacity either have this on hand or will make it quickly,” he said.