Glenmark said that this was the second clinical study after the successful Favipiravir monotherapy trial earlier this year.
The top drug regulator has also asked for an explanation on the "pricing" of the drug.
This marks company's first abbreviated new drug application (ANDA) approval out of its new North American manufacturing facility based in Monroe, North Carolina.
The Glenmark study will examine whether early administration of a combination of Favipiravir and Umifenovir enhances antiviral efficacy.
Glenmark Pharma gets DCGI nod for clinical trials of Favipiravir antiviral tablets on COVID-19 patients
Favipiravir has demonstrated activity against influenza viruses and has been approved in Japan for the treatment of novel influenza virus infections, it added.