The COVID-19 virus has caused a global emergency and has attracted the attention of healthcare professionals and the public around the world. The significant increase in the number of new cases of infection with this virus demonstrates the relevance of the search for drugs that are effective against this pathogen. The aim of this work was to evaluate the antiviral efficacy of Mefloquin® against COVID-19. The antiviral efficacy of Mefloquin® against the new pandemic virus SARS-CoV-2 was studied in in vitro experiments in Vero C1008 cell culture and in vivo on Syrian golden hamsters. The results of the study revealed that the drug Mefloquine® at a concentration of 2.0 µg ml-1, when applied after infection of cells, suppresses the reproduction of the SARS-CoV-2 virus by 1.7–1.9 lg, the inhibition rate is about 99%. When using Mefloquine, pathological changes in the lung tissue were less pronounced than in the control group. 6 days after infection, it was shown that when using Mefloquine, there was a statistically significant decrease in viral load in the lungs of infected Syrian golden hamsters, with an inhibition rate of 95.5%.
