Another two dozen patients have reported undesirable side effects after taking Plaquenil – the brand name of hydroxychloroquine – as well as other medicines such as the antiretroviral Kaletra, the agency's head Dominique Martin told AFP.
He said experts were trying to determine whether the drugs were linked to the side effects, with initial conclusions expected by the end of the week.
The drug safety agency (ANSM) began boosting its surveillance two weeks ago of trials of drugs against COVID-19, “in particular when they are used outside of clinical trials of chloroquine, hydroxychloroquine, azithromycin, lopinavir/ritonavir (Kaletra), tocilizumab (and) colchicine,” Martin said.
“It's perfectly normal that treatments be tried, given the circumstances, but that doesn't mean we shouldn't observe surveillance… of these substances,” Martin said.
Combining hydroxychloroquine with the antibiotic azithromycin has been in the spotlight since French researcher Didier Raoult published two studies that he said showed the treatment's effectiveness against COVID-19.
The treatment needs “particular attention”, Martin said, because using the two drugs together runs the risk of arrhythmia and could provoke a heart attack.
This was “even more the case with patients suffering from COVID-19” because of metabolic problems associated with the disease, he said.
Health Minister Olivier Véran last week opened for giving chloroquine to the most severe coronavirus cases, but only under strict supervision.
Chloroquine is a synthetic form of quinine, which has been used to treat malaria since the 1940s. Hydroxychloroquine shares a similar mechanism of action but is less toxic.