The antiviral activity of remdesivir, an investigational treatment for coronavirus disease 2019 (COVID-19), may potentially be reduced if it is coadministered with chloroquine or hydroxychloroquine, according to the Food and Drug Administration (FDA). 

In a press statement, the Agency warned clinicians about this potential drug interaction, which is based on in vitro data that showed an antagonistic effect of chloroquine on the intracellular metabolic activation and antiviral activity of remdesivir. As such, concomitant use of remdesivir with chloroquine or hydroxychloroquine is not recommended. 

At this time, reduced antiviral activity has not been reported in the clinical setting, but the FDA is continuing to evaluate data as it becomes available. “We understand that, as we learn more about these products, changes may be necessary based on new data – such as today’s updates for healthcare providers about a potential drug interaction and other important information about using remdesivir to treat COVID-19 patients,” said Patrizia Cavazzoni, MD, acting director of the FDA’s Center for Drug Evaluation and Research. 

Remdesivir, a nucleotide analogue with broad spectrum antiviral activity, was granted emergency use authorization (EUA) in May 2020 following preliminary results from a National Institutes of Health (NIH) study that showed the treatment was associated with a shorter time to recovery in patients hospitalized with COVID-19. As part of the EUA, a fact sheet must be made available to healthcare providers that includes prescribing information for the investigational agent. In light of the new finding, the fact sheet for remdesivir has been updated to include the potential interaction. Moreover, based on results from both the NIH trial and a Gilead-sponsored study, updates have been made to clarify dosing and administration recommendations, and additional safety data has been added.

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“As we have done throughout the pandemic, the FDA continues to evaluate all of the emergency use authorizations issued and their related materials and will continue to make changes as appropriate based on emerging science and data,” Cavazzoni added. Recently, the Agency revoked the EUA for chloroquine and hydroxychloroquine based on new information suggesting that the potential benefits of these agents in treating COVID-19 no longer outweighed the risks.

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