A drug called favipiravir, developed by a subsidiary of Fujifilm called Fujifilm Toyama Chemical, has generated encouraging outcomes based on clinical trials in Wuhan and Shenzhen involving 340 patients. The drug has been developed to address new strains of influenza.
Chinese Clinical Trials
Zhang Xinmin, an official with China’s science and technology ministry, reported that patients in Shenzhen participating in the clinical trial reported good outcomes for the virus after a median of four days after testing positive compared to a median of 11 days for those not treated with this drug, reported The Guardian. Moreover, patient X-rays showcased improvements in lung condition for about 91% of the patients taking favipiravir versus 62% of those not taking the drug.
The Drug Developer
Fujifilm Toyama Chemical developed the drug known as Avigan—in 2014, declined to comment on these claims coming out of China. However, their share price surged this morning by as much as 14.7%.
The Drug Shows Promise
Also called Avigan, it is an antiviral drug under development by Toyama Chemical of Japan with activity against many RNA viruses. By February 2020 the drug was being assessed in China for experimental treatment of the emergent COVID-19 disease—and as reported recently, it was found to be effective in treating the infection in two clinical trials in Wuhan and Shenzhen.
Avigan has been shown to be active against influenza viruses, West Nile virus, yellow fever virus, foot and mouth disease virus, as well as flaviviruses, arenaviruses, bunya viruses and alphaviruses. The drug has also evidenced activity against enteroviruses and Rift Valley fever virus.
Moreover, the drug has demonstrated limited efficacy against Zika virus in animal studies, but ultimately has represented less promise than MK-608.
Its mechanism of action is purported to be related to the selective inhibition of viral RNA-dependent RNA polymerase. Other studies have led researchers to suggest that favipiravir induces lethal RNA transversion mutations, generating a nonviable viral phenotype. As a prodrug, it metabolizes to its active form, favipiravir-ribofuranosyl-5′-triphosphate (favipiravir-RTP), available in both oral and intravenous formulations. Favipiravir does not inhibit RNA or DNA synthesis in mammalian cells and is not toxic to them. In 2014, favipiravir was approved in Japan for stockpiling against influenza pandemics. However, favipiravir has not been shown to be effective in primary human airway cells, casting doubt on its efficacy in influenza treatment.
The drug showed some promise based on preclinical research in a mouse model or Ebola virus disease, but the efficacy of this application is unproven, While early stage reports suggest the drug could be effective in treating COVID-19.
Clinical Trials in Japan
Apparently, physicians in Japan have embraced the drug for coronavirus studies in that country. The emphasis there is on patients with mild to moderate symptoms. However, reports picked up by The Guardian report that the drug is not as effective in patients with severe symptoms. A source noted “We’ve given Avigan to 70 – 80 people, but it doesn’t seem to work that well when the virus has already multiplied.” Moreover, the UK paper reports that similar challenges have been observed in studies involving coronavirus patients using a combination of the HIV antiretrovirals lopinavir and ritonavir.
Currently, there are no approvals for the use of Favipiravir for full-scale use for COVID-19 patients as it was not developed with this condition. However, a health official informed the Mainichi that the drug could be approved by May. Key will be clinical trials results.