The Food and Drug Administration has granted an emergency use authorization to a drug for treating Covid-19, although there is little evidence so far to demonstrate that it works.
In a letter Saturday to Rick Bright, director of the Department of Health and Human Services’ Biomedical Advanced Research and Development Authority, FDA chief scientist Denise Hinton wrote that the agency had granted Bright’s request for an EUA for oral formulations of hydroxychloroquine sulfate and chloroquine phosphate, two closely related malaria drugs that have been tested as treatments for Covid-19.
The EUA includes certain restrictions: Patients must have a valid prescription from a doctor giving the drugs within a limited scope of authorization, and only supplies of the drugs from the Strategic National Stockpile issued to public health authorities can be used. The agency said it was issuing the EUA to facilitate the drugs’ availability for patients for whom clinical trials are unavailable or for whom participation is not feasible.
The decision comes ahead of pivotal data definitively showing whether or not the drugs are effective against Covid-19, the disease caused by the SARS-CoV-2 virus. The evidence that does exist to support the drugs’ use is rather scant.
Researchers in Marseille, France, conducted a non-randomized controlled study of 36 Covid-19 patients, giving hydroxychloroquine and the antibiotic azithromycin to 20 and using the remaining 16 as controls. Early results showed that among the 20 who received the drug, 70% were virologically cured, compared with 12.5% of those in the control arm. Follow-up data, among 80 patients, showed clinical improvement in all but two patients, both elderly, one of whom died while another remained in the intensive care unit. Patient respiratory samples showed 97.5% of patients were negative after five days.
But results from a study by Chinese researchers, published in China’s Journal of Zhejiang University, showed that patients given hydroxychloroquine did no better than those who did not receive it. For that trial, researchers enrolled 30 patients who received standard treatment and gave the drug to 15, finding that approximately equal numbers in both arms tested negative for the virus after a week, with no statistically significant difference between the two arms.
Nevertheless, President Donald Trump has enthusiastically promoted hydroxychloroquine and chloroquine despite the absence of firm evidence for their efficacy. Reports have since emerged of runs on the drugs at pharmacies, leaving patients who take them to treat autoimmune disorders unable to obtain them. Meanwhile, a couple in Phoenix was hospitalized, and the husband died, after drinking chloroquine phosphate-based fish tank cleaner.
Numerous clinical trials are listed on ClinicalTrials.gov testing chloroquine or hyroxychloroquine in Covid-19. Other drugs in development include Gilead Sciences’ remdesivir as well as Regeneron Pharmaceuticals and Sanofi’s Kevzara (sarilumab).
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