Favipiravir: A Potential Antiviral for COVID-19?

摘要

Evidence supports clinical trials to determine whether this broad antiviral drug is effective in treating COVID-19. Researchers review the evidence for testing various drugs in treating COVID-19. Among the drugs reviewed is favipiravir, also known as T-705 or Avigan, a pyrazine derivative that acts as an inhibitor of viral RNA-dependent RNA polymerase, causing chain termination and preventing RNA elongation. Favipiravir has demonstrated activity against influenza viruses, including those that are oseltamivir-resistant, and has been approved in Japan and China for the treatment of novel influenza virus infections. However, it is a mutagen and has potential for both teratogenicity and embryotoxicity in humans. It is orally available and is dosed twice daily in treating influenza. It has also been used for postexposure prophylaxis and treatment for Ebolavirus infection. It has no activity against DNA viruses. With regard to COVID-19, lay media have reported on a non-placebo, openlabel trial in Shenzhen, China, of oral favipiravir (1600 mg twice daily for 1 day, then 600 mg twice daily) plus inhaled interferon compared with a historical cohort of patients receiving lopinavir/ritonavir for 14 days (Med News Today; 2020 Mar 27). Those receiving favipiravir and interferon had median shedding of virus of 4 days, compared with 11 days in the lopinavir/ ritonavir group. Radiographic improvement was seen in 91% of favipiravir-interferon treated subjects compared with 62% of those on lopinavir/ritonavir. The results of this study have not been published in a peer-reviewed journal to date. A prospective, multicenter, open-label, randomized trial in China comparing favipiravir with umifenovir (Arbidol), a membrane-fusion inhibitor active against influenza viruses, was recently reported (MedRxiv 2020 Mar 27; [e-pub]). It demonstrated a higher clinical recovery rate at day 7 in those on favipiravir among moderately ill patients but not among mildly or severely ill patients.