What Is Avigan (Favipiravir)?
Avigan, a Japanese antiviral medication known generically as favipiravir, was developed in the late 1990s by a company later purchased by Fujifilm as the company transitioned from the photography industry into healthcare.
Favipiravir is designed to short circuit the reproduction capabilities of RNA viruses. “Avigan is a viral RNA polymerase inhibitor, with a new mechanism of action that inhibits viral gene replication within infected cells,” says Kana Matsumoto, a spokesperson for Fujifilm. “Due to this characteristic, the drug may potentially have an antiviral effect on the viruses classified into the same type (single-stranded RNA virus) as influenza virus.”
In the process of testing the drug against a range of viruses, scientists determined that the same properties that help favipiravir destroy viruses also makes it destructive to the rapid cell growth of fetuses. In other words, favipiravir may cause birth defects for pregnant women or those trying to conceive.
When the drug was finally approved in Japan in 2014, it was only granted for emergency use against flu epidemics. Accordingly, Japan provided favipiravir as an emergency treatment for the Ebola virus outbreak in 2016. Now favipiravir is also licensed in China, where it received approval as an investigational therapy for COVID-19.
Lessons Learned in Early Trials
The first clinical trial of favipiravir for the treatment of COVID-19 occurred in Shenzhen city in China. Of the 80 participants involved, those treated with favipiravir demonstrated better chest improvement while also testing negative for the genomic trace of COVID-19 in less time.
According to clinical trial results, favipiravir shortened the recovery time from 11 days to four days for mild and regular cases of COVID-19. A separate trial of the drug in Wuhan with 120 participants noted a shortened fever duration with favipiravir, from 4.2 days to 2.5 days.
Thanks to these promising results, Fujifilm began a Phase 3 trial of favipiravir at the beginning of April. This Phase 3 trial included about 100 patients with mild to moderate symptoms. Meanwhile, the Ministry of Health, Labor and Welfare in Japan reports that more than 2,000 people in Japan have been treated with favipiravir as part of clinical trials as of April 26.
Phase 2 clinical trials have also launched in the U.S, including at the University of Massachusetts Medical School. “We expect the drug will enhance clearance of viruses and shorten the duration of COVID-19 illness,” said Robert Finberg, chair of the school’s Department of Medicine. “Previous studies with this drug have indicated that it enhances clearance of influenza. We expect results in approximately one to two months.”
Approval Anticipated For June 2020
Though Japan’s Prime Minister Shinzo Abe hoped to approve favipiravir for the treatment of COVID-19 by May, that approval has been postponed until June or later, according to health minister Katsunobu Kato. Clinical tests must continue into the early summer before the drug’s efficacy can be confirmed.