Scientists from Japan have identified the anti-malarial drug mefloquine as a potential candidate to treat COVID-19. Anti-malarial drugs like hydroxychloroquine and chloroquine were repurposed against COVID-19 in the early phase of the pandemic. However, several clinical trials failed to prove the expected efficacy.
The researchers studied 27 anti-parasitic/anti-protozoal drugs for screening. Using a cytopathic effect assay, mefloquine was identified as a potent anti-SARS-CoV-2 drug. Antiviral efficacy of mefloquine with other chloroquine derivatives was compared and it was revealed that mefloquine has the highest antiviral activity against SARS-CoV-2. A higher hydrophobicity of mefloquine due to t two trifluoromethyl groups may be responsible for such high antiviral efficacy.
They also conducted the time-of-addition analysis. They observed that mefloquine, when applied at the viral entry phase significantly reduced the viral RNA level. Mefloquine prevents the viral entry probably by inhibiting proteolytic cleavage of spike protein, virus-host cell membrane fusion, and virus translocation to the replication site.
Ref link: https://www.biorxiv.org/content/10.1101/2020.11.19.389726v1