What we currently know about using hydroxychloroquine for Covid-19
The anti-malaria drug hydroxychloroquine, sold under the brand name Plaquenil, is also prescribed as an anti-inflammatory drug for conditions like arthritis and lupus. It’s a derivative of another anti-malaria drug, chloroquine.
Hydroxychloroquine is an appealing prospect because it’s already been tested in humans and is available in a low-cost generic form. Doctors in several countries, including the
United States,
France, China, and South Korea, have reported success in treating Covid-19 patients with hydroxychloroquine, sometimes paired with the antibiotic azithromycin.
But these are anecdotes that don’t offer much insight into how effective the drug could be in a wider population.
A
laboratory study of hydroxychloroquine showed that it could prevent SARS-CoV-2, the virus behind Covid-19, from entering cells in a petri dish. While it shows a plausible mechanism for the drug, the effects on cells in a dish can be different from those in living people.
Human trials of hydroxychloroquine, by contrast, have so far yielded mixed results. A tiny study by researchers in France found that the drug could clear the infection in a few days. But the study sample included only 36 patients, and the trial wasn’t randomized, meaning the administrators were deliberately picking which patients received the treatment, potentially skewing the results.
Other studies have been even less promising. A study in China found that hydroxychloroquine was no better than standard medical treatments without the drug. This study was also small, 30 patients, but the treatment was randomized. Another study in France among 11 patients found that hydroxychloroquine was ineffective at best, with one patient dying, two transferred to an intensive care unit, and one patient who experienced a dangerous heart problem and had the hydroxychloroquine treatment stopped early.
In
Sweden, some hospitals have stopped offering the drug after some patients reported seizures and blurred vision.
The listed side effects of hydroxychloroquine are long and well-known. The Food and Drug Administration (FDA) has reported problems like irreversible retinal damage, cardiac arrhythmias, muscle weakness, and a severe drop in blood sugar. There are psychiatric effects as well, including insomnia, nightmares, hallucinations, and suicidal ideation. The drug can also have harmful interactions with medicines used to treat diabetes, epilepsy, and heart problems.
These side effects are a big reason why the World Health Organization no longer recommends hydroxychloroquine as the routine
treatment for malaria.
Some health workers have been hoarding hydroxychloroquine as a means to ward off the illness. Several
patients who need the drug for approved uses have reported trouble getting their prescriptions filled. But there’s
no evidence that the drug works as a prophylactic for Covid-19.
Some of the rules for drugs like hydroxychloroquine have now been relaxed to allow doctors to experiment with treatments for patients in dire need during the pandemic.
The FDA has granted
emergency use authorization of hydroxychloroquine and chloroquine to fight Covid-19. But expanding the use of these drugs to sick but not critical patients still warrants further testing due to the potential side effects.
High blood pressure and diabetes, for example, already make the infected more likely to suffer severely from Covid-19. So a treatment like hydroxychloroquine could worsen those underlying conditions, or could result in a dangerous interaction with the medicines used to treat those conditions.
More than 50
clinical trials for the drug are now planned or underway around the world. But while randomized controlled trials do help health workers figure out how to safely deploy drugs, they don’t guarantee the drug will work for everyone, nor will they eliminate risks completely.