Brazilian researchers link high doses of chloroquine to deaths

Presented by Brazilian President Jair Bolsonaro as a “possible cure” to Covid-19, antimalarial drugs chloroquine and hydroxychloroquine have become one of the biggest hot-button issues surrounding the pandemic. There isn’t enough scientific evidence attesting to the drug’s effectiveness to treat Covid-19 — and a Brazilian study carried out in the Amazonian city of Manaus suggests that it may actually be harmful.

Researchers halted their trials after observing that patients who received higher doses of chloroquine showed alterations in their heart rates — presenting QT intervals over 500 milliseconds —  and higher lethality rates — 17 percent, against 13.5 percent among similar patients not using the drug. In a yet to be peer-reviewed study, the researchers say chloroquine “should not be recommended for Covid-19 treatment because of its potential safety hazards.”

From the start, physician Marcus Lacerda, who led the trials on mild patients in Manaus, called for caution. “We do research to tell whether a drug works or not. And chloroquine might not work. There is a great chance that we won’t find an antiviral drug against the coronavirus — it is hard to do so against respiratory viruses. Researchers can’t skew the data in order to prove something no matter what, turning a blind eye to negative results if [the drug] doesn’t work,” he said.

You can read a preprint of the paper here: “Chloroquine diphosphate in two different dosages as adjunctive therapy of hospitalized patients with acute respiratory distress syndrome in the context of coronavirus (SARS-CoV-2) infection: Preliminary safety results of a randomized, double-blinded, phase IIb clinical trial (CloroCovid-19 Study).”

The president and the medicine

Chloroquine is by no means the first drug Jair Bolsonaro endorsed before scientific evidence warranted him to do so. As reporter André Cabette Fábio wrote on April 9, years before Mr. Bolsonaro was considered a viable presidential candidate, the then member of Congress gained national attention in 2016 while promoting a bill to legalize an unproven cancer treatment known simply as “the cancer pill.”

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