In the UK, Robin May, Professor of Infectious Disease at the University of Birmingham, explained that there is a scientific rationale for the use of hydroxychloroquine in the treatment of COVID-19, based on its mode of action in malaria.
In a statement through the Science Media Centre, he explained that, as chloroquine is a “weak base” and so helps to neutralise acids, it makes the environment “less suitable” for the malaria parasite to live in when it diffuses into red blood cells.
While the mode of action against COVID-19 is not established, Prof May said, he pointed out that many viruses enter host cells via endocytosis, as a result of which they are initially taken up into an intracellular ‘compartment that is “typically fairly acidic”.
“Chloroquine would alter the acidity of this compartment, which can interfere with the ability of viruses to escape into the host cell and start replicating.”
He continued: “Another possibility is that chloroquine may alter the ability of the virus to bind to the outside of a host cell in the first place,” adding that the drug “has subtle effects on a wide variety of immune cells…and it may be that one of these effects helps stimulate the body’s ability to fight off COVID-19.”
Crucially, the drug is also “cheap and relatively easy to manufacture” and so could easily be put into clinical trials and, eventually, treatment, May underlined.
The study by Yao et al was supported by the “13th Five-Year” National Major New Drug Projects of China, Ministry of Science and Technology of the People’s Republic of China, and Bill & Melinda Gates Foundation.
Two of its authors have patents pending for an anti-microbial infection pharmaceutical composition and its application.
Professor Pialoux has been a board member or attended meetings for Gilead, MSD, Bristol-Myers Squibb, Janssen, Abbvie, AstraZeneca.
Clin Infect Dis. 2020 Mar 9. pii: ciaa237. doi: 10.1093/cid/ciaa237
Editor’s note, 18th March 2020: This article was updated to include Prof May’s comments. On 19th March the US FDA issued a statement on chloroquine: “The FDA has been working closely with other government agencies and academic centers that are investigating the use of the drug chloroquine, which is already approved for treating malaria, lupus and rheumatoid arthritis, to determine whether it can be used to treat patients with mild-to-moderate COVID-19 to potentially reduce the duration of symptoms, as well as viral shedding, which can help prevent the spread of disease. Studies are underway to determine the efficacy in using chloroquine to treat COVID-19.”