Adding High-Dose Chloroquine Not Advised for Severe COVID-19

High-dose versus low-dose group had higher lethality until day 13, more instances of QTc interval >500 ms

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TUESDAY, April 28, 2020 (HealthDay News) -- High-dosage chloroquine diphosphate (CQ) has potential safety hazards when used as adjunctive therapy for patients hospitalized with severe COVID-19, according to a study published online April 24 in JAMA Network Open.

Mayla Gabriela Silva Borba, M.D., from the Fundação de Medicina Tropical Dr Heitor Vieira Dourado in Brazil, and colleagues examined the safety and efficacy of two CQ dosages in a phase IIb clinical trial involving 81 adult patients hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients were allocated to receive high- or low-dosage CQ (600 mg twice daily for 10 days or 450 mg twice daily on day 1 and once daily for four days). All patients received azithromycin, and most also received oseltamivir.

The high-dosage group included more patients of older age (54.7 versus 47.4 years) and more heart disease (17.9 versus 0 percent). The researchers found that viral DNA was detected in 77.5 and 75.6 percent of 40 and 41 patients in the low- and high-dosage groups, respectively. Lethality until day 13 was 39 and 15 percent in the high- and low-dosage groups, respectively. Compared with the low-dosage group, the high-dosage group had more instances of a QTc interval greater than 500 ms (18.9 versus 11.1 percent).

"One can only conclude from this trial that high-dose chloroquine (and by close association, hydroxychloroquine) in combination and azithromycin and possibly oseltamivir, is potentially associated with increased mortality among patients with severe, suspected COVID-19," write the authors of an accompanying editorial.

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