French drugmaker Sanofi said Friday it is suspending recruitment of new patients for its clinical trials looking at anti-malaria drug hydroxychloroquine as a potential treatment for the coronavirus.
The company is also putting a hold on supplying the drug for off-label use to treat Covid-19 until safety concerns are cleared by the World Health Organization.
"Patient safety is Sanofi's primary focus," a Sanofi spokesperson said in a statement to CNBC. "In line with WHO's decision and out of caution, Sanofi has decided to temporarily suspend the recruitment of new patients in both of its clinical trials in COVID-19 patients, pending reassurance on the safety profile of HCQ."
On Monday, WHO said it temporarily suspended its trial of hydroxychloroquine while the safety data is reviewed by the Data Safety Monitoring Board. The announcement came days after a study published in medical journal The Lancet found that hospitalized Covid-19 patients treated with hydroxychloroquine had a higher risk of death than those who didn't take it.
Patients who took the drug or chloroquine, which hydroxychloroquine is derived from, were also more likely to develop irregular heart rhythms, according to the study, which looked at more than 96,000 patients from 671 hospitals across six continents.
Hydroxychloroquine is often used by doctors to treat rheumatoid arthritis and lupus. It is known to have serious side effects, including muscle weakness and heart arrhythmia.
Even though it isn't a proven treatment against the coronavirus, doctors can give the drug to patients in a common and legal practice known as "off-label" prescribing. "Off label" means the drug is being used for an ailment not yet approved by the Food and Drug Administration.
Earlier this month, President Donald Trump disclosed he was taking hydroxychloroquine daily to prevent infection from the coronavirus. White House physician Dr. Sean Conley released a memo, which said that after discussing evidence for and against hydroxychloroquine with Trump, they concluded "the potential benefit from treatment outweighed the relative risks."