Chloroquine Trial in COVID-19 Patients Paused Over Safety Hazards

Researchers in Brazil prematurely halted a high-dose study of chloroquine in COVID-19 patients after seeing “toxicity red flags.”

Preliminary data from the study of 81 hospitalized patients suggest that a high-dose regimen of 600 milligrams twice daily for 10 days poses safety risks to certain patients and should not be recommended for treatment, according to the researchers at the Fundação de Medicina Tropical, a government hospital in Manaus.

According to the researchers, the higher doses of the drug caused irregular heart rhythms in some patients, particularly older individuals being treated with the antibiotic azithromycin and the antiviral oseltamivir.

Eleven patients died by day six of the 10-day regimen  and the remaining patients were moved to a low-dose arm of 2.7 grams total over five days. Not enough patients have been enrolled in the low-dose arm to estimate whether chloroquine offers a clear benefit.

Researchers in other countries also have reported safety concerns over chloroquine and hydroxychloroquine. France’s drug safety agency reported 43 cases of cardiac-related adverse effects linked to hydroxychloroquine. Seven cases of sudden death were reported, including three patients who were resuscitated. As in the Brazilian study, the adverse effects were seen in particular in combination with azithromycin.

“This initial assessment shows that the risks, in particular cardiovascular, associated with these treatments are very present and potentially increased in COVID-19 patients,” the National Agency for the Safety of Medicines and Health Products said.

On the other hand, early results from a small trial in China showed promising results for hydroxychloroquine in treating COVID-19 patients. Patients receiving the anti-malaria drug had notably shorter recovery times for fever and cough, and the drug helped treat pneumonia in most patients (DID, April 2).

In South Dakota, Sanford Health, a rural nonprofit health care system, announced Monday that it is leading a trial of hydroxychloroquine in 2,000 outpatients exposed to COVID-19. — James Miessler