Chloroquine and hydroxychloroquine, either alone or in combination with the antibiotic azithromycin, show no significant antiviral activity against infections with the novel coronavirus in macaques or human lung cells, according to two new studies in the journal Nature.
Hydroxychloroquine (HCQ) and chloroquine, two drugs commonly used to treat malaria, have been studied in more than 80 registered clinical trials for their potential to treat COVID-19. They have been shown to inhibit the novel SARS-COV coronavirus -2 infection in cell cultures, the scientists said.
However, they said the effectiveness of these drugs in the treatment of patients with COVID-19 was discussed.
In one of the studies, scientists, including Roger Le Grand from the French National Institute for Health and Medical Research, examined the effects of HCQ treatment in cynomolgus macaques, a non-human primate model of SARS-CoV-2 infection in humans.
They found that regardless of when treatment started, HCQ showed no significant antiviral activity either before infection, shortly after infection, or late after infection.
According to the study, the use of the antimalarial drug in combination with azithromycin, an antibiotic, also had no significant effect on the virus concentration in the macaques.
In the other study, Stefan Pohlmann and his colleagues from the Leibniz Institute for Primate Research in Germany found that chloroquine has no antiviral activity against SARS-CoV-2 in human lung cells.
They explained that in previous experiments, the cells used to show a positive effect for chloroquine did not have an enzyme that is normally present in human lung cells and facilitates the entry of SARS-CoV-2.
The scientists who conducted this study emphasized the importance of using cell lines that mimic human lung tissue in studies evaluating the activity of drugs against SARS-CoV-2.
According to the scientists, these results do not support the use of hydroxychloroquine and chloroquine in the treatment of patients with COVID-19.
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