Trending Clinical Topic: Hydroxychloroquine

Ryan Syrek


May 22, 2020

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Concerns about potential adverse effects, studies that show limited efficacy, and guidance about treatment protocols resulted in hydroxychloroquine becoming this week's top trending clinical topic. Hydroxychloroquine, an antimalarial drug, is one of several unproven agents that have been investigated for the potential to prevent or reduce severity and duration of COVID-19 infection.

As of April 30, 155 randomized clinical trials were listed on exploring the use of hydroxychloroquine or chloroquine for COVID-19 prophylaxis in more than 85,000 healthy individuals. However, many of these trials do not include ECG assessment to either exclude people at high risk of developing a cardiac arrhythmia or to identify patients who develop a dangerous QTc interval during use of hydroxychloroquine. Two studies released on May 1 provided further evidence of the risk for serious arrhythmias.

A study from Boston of 90 patients with confirmed COVID-19 treated with hydroxychloroquine found that 23% had notable prolongation of QTc intervals. One of the patients developed torsades de pointes following treatment with a combination of hydroxychloroquine and azithromycin. The second study, which was from France, found that 37 of the 40 patients (93%) with COVID-19 treated with hydroxychloroquine had some increase in QTc interval, but none of the patients developed an identified ventricular arrhythmia.

Elsewhere, a study of 150 hospitalized adults in China found that hydroxychloroquine does not help clear the SARS-CoV-2 virus or relieve the symptoms of COVID-19. Experts caution, however, that because of confounders, the trial does not definitively answer whether the drug can benefit such patients. The findings of the Chinese researchers were echoed by results of a retrospective study of Veterans Affairs patients hospitalized with COVID-19, which showed that hydroxychloroquine with or without azithromycin did not reduce the risk of requiring mechanical ventilation. It also found an increased risk for death associated with the administration of hydroxychloroquine alone.

In late April, the US Food and Drug Administration (FDA) released a communication that stated "the FDA is aware of reports of serious heart rhythm problems in patients with COVID-19 treated with hydroxychloroquine or chloroquine, often in combination with azithromycin and other QT-prolonging medicines. We are also aware of increased use of these medicines through outpatient prescriptions." The agency reiterated that treatment with hydroxychloroquine and chloroquine in patients with COVID-19 should occur only in a hospital and when participation in a clinical trial is "not available" or "not feasible."

As a result, hospitals in the United States have begun incorporating that guidance into their treatment protocols. While some had already taken a cautious approach to the drug's use, others changed their approaches on the basis of the FDA's guidance.

As the potential role—or lack of a role—of hydroxychloroquine in the treatment and prevention of COVID-19 becomes clearer with further investigation, it is likely to remain a subject of great interest.

Read more about investigational drugs and therapies used in treating COVID-19.


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