FDA warns hydroxychloroquine may weaken effectiveness of coronavirus drug remdesivir

The Food and Drug Administration warned Monday that Covid-19 patients taking anti-malaria drug hydroxychloroquine along with antiviral drug remdesivir may weaken the effectiveness of the latter.

The FDA is revising its fact sheet for health-care providers that accompanies remdesivir to state “that co-administration of remdesivir and chloroquine phosphate or hydroxychloroquine sulfate is not recommended as it may result in reduced antiviral activity of remdesivir.”

A recently completed nonclinical study discovered the potential drug interaction, the agency said in its notice published Monday evening. 

“The agency is not aware of instances of this reduced activity occurring in the clinical setting but is continuing to evaluate all data related to remdesivir,” the FDA wrote.

Remdesivir, manufactured by Gilead Sciences, was granted emergency use authorization by the FDA to treat hospitalized patients sickened with Covid-19 in May. Hydroxychloroquine had also been granted an EUA for the coronavirus, but the designation was revoked earlier Monday after the FDA found it was unlikely to be effective.

The news of the potential drug interaction is likely to further dampen hopes that hydroxychloroquine is helpful against the coronavirus.

The drug generated excitement earlier in the year after a handful of small studies suggested it could be beneficial and President Donald Trump promoted the drug as a potential treatment for the virus.

However, several larger studies later showed the drug was not helpful and also caused heart issues in some patients. 

A recent study published in the New England Journal of Medicine found hydroxychloroquine was no better than a placebo in preventing infection of the coronavirus.

The study, the first randomized, placebo-controlled trial, which is considered the “gold standard” in science, looked at more than 800 people in the United States and Canada who had been exposed to the coronavirus.