New York, Aug 31 (IANS): Hydroxychloroquine (HCQ) -- approved by the US Food and Drug Administration (FDA) to treat or prevent malaria as well as some auto-immune conditions -- does not help in recovery of patients hospitalised due to Covid-19, but may cause harm, researchers have warned.

In 2021, in the US alone, there have been more than 560,000 prescriptions of hydroxychloroquine for the prevention, post-exposure, and treatment of Covid-19. In 2020, the 890,000 prescriptions for hydroxychloroquine were nine-fold greater than the previous years.

In a commentary published in The American Journal of Medicine, researchers from Florida Atlantic University, reviewed the recent major randomised, double-blind placebo-controlled trials and present an updated meta-analysis of hydroxychloroquine in post-exposure prophylaxis as well as in hospitalised patients.

In addition to a lack of significant benefit, the new evidence shows some suggestion of harm.

The prior reassuring safety profile of hydroxychloroquine is applicable to patients with lupus and rheumatoid arthritis, both of which are of greater prevalence in younger and middle-age women, whose risks of fatal heart outcomes due to hydroxychloroquine are reassuringly very low.

In contrast, the risks of hydroxychloroquine for patients with Covid-19 are significantly higher because fatal cardiovascular complications due to these drugs are so much higher in older patients and those with existing heart disease or its risk factors, both of whom are more predominant in men, researchers said.

Last year, the same researchers issued a plea for a moratorium on prescription of hydroxychloroquine in prevention or treatment pending the outcome of ongoing randomised trials.

"The updated randomised evidence provides even stronger support for the halt on prescribing hydroxychloroquine in the prevention or treatment of Covid-19," said Charles H. Hennekens, Professor in FAU's Schmidt College of Medicine.

"Premature and avoidable deaths will continue to occur if people take hydroxychloroquine and avoid the public health strategies of proven benefit, which include vaccinations and masking," he added.

A WHO-led trial, last year, evaluated four drugs -- remdesivir, hydroxychloroquine, lopinavir, and interferon -- for treatment against Covid. The results showed that the drugs had little or no effect on hospitalised patients with Covid-19. Remdesivir and HCQ did not affect the degree of respiratory failure or inflammation.