The Food and Drug Administration (FDA) is notifying health care providers that co-administration of remdesivir and chloroquine phosphate or hydroxychloroquine sulfate for the treatment of COVID-19 is not recommended, as it may result in reduced antiviral activity of remdesivir.

Remdesivir (Gilead Sciences Inc.) is an intravenously administered, direct acting antiviral drug that inhibits viral RNA synthesis. It is an investigational drug and is not currently approved by the FDA for any indication. On May 1, 2020, the FDA issued an Emergency Use Authorization (EUA) for remdesivir to allow remdesivir to be distributed and used by licensed health care providers to treat adults and children hospitalized with severe COVID-19. A newly completed in vitro laboratory study demonstrated an antagonistic effect of chloroquine on the intracellular metabolic activation and antiviral activity of remdesivir, which prompted the FDA’s new recommendation.

The FDA revoked the EUA for chloroquine and hydroxychloroquine for the treatment of COVID-19 on June 15, 2020, based on evidence that the drugs may not be effective for this indication.

Food and Drug Administration (FDA). Coronavirus (COVID-19) Update: FDA Warns of Newly Discovered Potential Drug Interaction That May Reduce Effectiveness of a COVID-19 Treatment Authorized for Emergency Use [news release]. June 15, 2020. Available at: click here. Accessed June 16, 2020.