Enisamium is an inhibitor of the SARS-CoV-2 RNA polymerase and shows improvement of recovery in COVID-19 patients in an interim analysis of a clinical trial

Olha Holubovska, Denisa Bojkova, Stefano Elli, Marco Bechtel, David Boltz, Miguel Muzzio, Xinjian Peng, Frederico Sala, Cesare Cosentino, Alla Mironenko, Jens Milde, Yuriy Lebed, Holger Stammer, Andrew Goy, Marco Guerrini, Lutz Mueller, Jindrich Cinatl, Victor Margitich, and Aartijan J.W. te Velthius

Pandemic SARS-CoV-2 causes a mild to severe respiratory disease called Coronavirus Disease 2019 (COVID-19). Control of SARS-CoV-2 spread will depend on vaccine-induced or naturally acquired protective herd immunity. Until then, antiviral strategies are needed to manage COVID-19, but approved antiviral treatments, such as remdesivir, can only be delivered intravenously. Enisamium (laboratory code FAV00A, trade name Amizon®) is an orally active inhibitor of influenza A and B viruses in cell culture and clinically approved in countries of the Commonwealth of Independent States. Here we show that enisamium can inhibit SARS-CoV-2 infections in NHBE and Caco-2 cells. In vitro, the previously identified enisamium metabolite VR17-04 directly inhibits the activity of the SARS-CoV-2 RNA polymerase. Docking and molecular dynamics simulations suggest that VR17-04 prevents GTP and UTP incorporation. To confirm enisamium’s antiviral properties, we conducted a double-blind, randomized, placebo-controlled trial in adult, hospitalized COVID-19 patients, which needed medical care either with or without supplementary oxygen. Patients received either enisamium (500 mg per dose) or placebo for 7 days. A pre-planned interim analysis showed in the subgroup of patients needing supplementary oxygen (n = 77) in the enisamium group a mean recovery time of 11.1 days, compared to 13.9 days for the placebo group (log-rank test; p=0.0259). No significant difference was found for all patients (n = 373) or those only needing medical care (n = 296). These results thus suggest that enisamium is an inhibitor of SARS-CoV-2 RNA synthesis and that enisamium treatment shortens the time to recovery for COVID-19 patients needing oxygen.


SARS-CoV-2 virus, COVID-19, infection, viral replication, EpiAirway (AIR-100), HCoV-NL63, alpha-coronavirus, Infectious disease research, viral infection

Materials Tested

enisamium (FAV00A, Amizon), SARS-CoV-2 virus, HCoV-NL63

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