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As the world waits impatiently for a COVID-19 vaccine, an exhaustive review of hydroxychloroquine and chloroquine pharmacology suggests that the doses used in COVID-19 prevention trials are safe, say University of Oxford affiliated researchers in a study published in PLoS Medicine.

Hand holding pills © 2020 MORU. Photographer: Supa-at Asarath.

“Hydroxychloroquine and chloroquine have become intensely politicised during the COVID-19 pandemic. It has been really hard for the public to separate fact from fiction“  said study co-author Assoc Prof Phaik Yeong Cheah, head of ethics and public engagement at the Mahidol Oxford Tropical Medicine Research Unit (MORU), Bangkok Thailand.

“There has been a lot of concern that hydroxychloroquine and chloroquine might be toxic, but using pharmacokinetic-pharmacodynamic information from healthy volunteers, patients with malaria and those with rheumatological diseases, as well as people who intentionally took overdoses, we show that the doses used in COVID-19 prevention and most treatment trials are very likely to be safe,” said study co-author Prof Joel Tarning, Head of Clinical Pharmacology at MORU.

Used for over 60 years to treat malaria, amoebic liver abscess and rheumatological conditions like lupus, billions of hydroxychloroquine or chloroquine treatments have been given. These drugs have recently been shown in the laboratory to kill the novel coronavirus (SARS-CoV-2), the virus that causes COVID-19. Hydroxychloroquine does not benefit patients hospitalised with COVID-19 infection, but studies have not examined whether it could work as prevention, where it has a much greater chance of being effective.

Unfortunately, because the whole subject has become so highly charged, say the scientists, large clinical trials like COPCOV – a global study to test if hydroxychloroquine and chloroquine can prevent COVID-19 in healthcare workers – are not being sufficiently promoted or supported. The prevention studies urgently need participants.

“I don’t know if hydroxychloroquine can prevent COVID-19 or not,” said study co-author Prof Sir Nick White, Co-Principal Investigator of the Oxford-led COPCOV clinical trial. “But I do know that we really need to find out, and quickly. All the negative publicity has naturally made people reluctant to enrol in studies. We could be waiting a long time for an effective vaccine.”

COPCOV now has 4 sites operating in the UK, with several more coming on line by end September It is the only non-vaccine COVID prophylaxis study badged as being of Urgent Public Health importance by the UK’s NIHR Clinical Research Network.

“We urge anyone working in UK health settings – nurses, care-assistants, doctors, therapists, dentists, dietitians, cleaners, porters, food service workers, phlebotomists, ambulance workers, radiographers – to enrol in our UK COVID-19 prevention study,” said Prof Martin Llewelyn from Brighton and Sussex Medical School, who as COPCOV UK’s Chief Investigator leads the Trial in the UK along with Prof Amanda Adler, director of the Diabetes Trials Unit within the Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM).

“We know that as used in COPCOV hydroxychloroquine is safe and there are good reasons to think it could offer valuable protection against COVID-19. It’s imperative that COPCOV finds out if it does,” said Prof Llewelyn.

Visit COPCOV UK to register and see which sites are taking part

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Paper:

COVID-19 prevention and treatment: A critical analysis of chloroquine and hydroxychloroquine clinical pharmacology. White NJ, Watson JA, Hoglund RM, Chan XHS, Cheah PY, Tarning J. PLoS Med 17(9): et003251.

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