Antiviral remdesivir combined with hepatitis C drugs is 10 times more effective in treating SARS-CoV-2 than remdesivir  administered on its own, a new study finds.

A collaborative team of researchers from Rensselaer Polytechnic Institute, the Icahn School of Medicine at Mount Sinai, and the University of Texas at Austin looked into the potential of repurposing available drugs as COVID-19 treatment for cases where a vaccine isn’t practical or effective. Looking into remdesivir, a COVID-19 treatment that received much media attention over the past year, the researchers found that its use as an intravenous drug is only limited to patients with more severe conditions that require hospital admission. By combining it with an orally administered hepatitis C drug, the efficacy of remdesivir is extended, making it possible for an oral drug combination to be taken by COVID-19 patients at home.

“Nearly 3 million people have died worldwide from COVID-19. There are situations where the vaccine isn’t the best option and it would be helpful to have orally available antivirals,” said Professor Gaetano Montelione, a member of the Rensselaer Center for Biotechnology and Interdisciplinary Studies (CBIS), in an intriguing press release. “Here, we see a promising synergy that, if confirmed through additional research and clinical trials, could provide a new antiviral to combat COVID-19.”

Several studies into the use of hepatitis C drugs in the treatment of COVID-19 have been underway as the world continues to grapple with ongoing challenges of the pandemic. In a previous blog, we discussed how the use of hepatitis C drugs boceprevir and narlaprevir could help reduce the rate and severity of COVID-19 infection.

In this study, the researchers discovered the synergistic effect of hepatitis drugs as part of an effort to identify existing drugs that could be used against COVID-19. Much interest in repurposing drugs for COVID-19 treatment banks on the hope of getting rapid approval of these drugs and/or combination therapy for clinical use, rather than relying upon newly developed drugs.

“Repurposed drugs have the potential to be tested and approved quickly for safe use, while more effective therapies are under development,” noted Robert Krug, virologist and professor emeritus at the University of Texas at Austin in a recent press release. Professor Krug helped initiate the collaboration, interpret the results, and write the study recently published in Cell Reports.

Remdesivir was originally developed not only to treat hepatitis C, but also the Ebola virus and other viral infections. It works by blocking viral replication. It targets a polymerase cluster, but many antivirals target viral proteases—in other words, enzymes that are required for the life cycle of the virus.

The study identified four hepatitis C drugs—simeprevir, grazoprevir, paritaprevir, and vaniprevir—that exhibited a synergistic effect when used in combination with remdesivir. The researchers found that when administering simeprevir on virus-infected cells, 10 times less remdesivir is needed to inhibit 90% of the virus than when remdesivir is used on its own. Using less remdesivir also reduces any adverse side effects from this powerful drug in treating COVID-19. Therefore, with vaccine availability for COVID-19 reaching all new heights in the U.S., and with recent findings for potentially higher efficacy for new SARS-CoV-2 treatment therapies — including one, thanks to hep C drugs — the first half of 2021 is already starting to feel rather promising.

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