Favipiravir is an antiviral drug that is approved both in Japan and China for influenza treatment. It is a potent drug that selectively inhibits the RNA-dependent RNA polymerase of RNA (RdRp) viruses. Favipiravir is a pyrazine carboxamide derivative developed by Toyama Chemical of Japan to act against many RNA viruses. It’s active against many viruses such as influenza virus, yellow fever virus, foot-and-mouth disease virus, West Nile virus, and flaviviruses. Its activity against Rift Valley fever and enteroviruses has also been demonstrated. However, drug should be use in treating viral strains only when all other anti-viral drugs remain unresponsive.
Favipiravir was approved in Japan to treat influenza virus cases in 2014. A year later, it was also approved in China for the treatment of the influenza virus. In 2019, this drug was approved for clinical use in China against the dreaded SAR-CoV2, the virus that causes coronavirus disease 2019 or COVID-19.
What is COVID-19?
COVID-19 is an infectious respiratory disease that originated in Wuhan, China in December 2019. Until now, the exact cause of the virus remains unknown but the first infection was believed to be linked to a live market in Wuhan, China.
For the past 3 months, China has been battling the new strain of coronavirus responsible for thousands of death worldwide to date. The new strain of virus that causes COVID-19 is not the same as the coronaviruses that spread among humans.
The race to find a cure
As confirmed cases of coronavirus disease continue to rise globally, treatment options are urgently and desperately needed. The World Health Organization launches a global mega trial against the COVID-19 known as Solidarity. Rather than coming up with the compound from scratch that may take years to develop and test, public health agencies and researchers all around the world are looking to repurpose drugs known largely to be safe and already approved for other diseases. Researchers around the world are racing to find a cure focusing on the existing anti-malarial drugs like Chloroquine and hydroxychloroquine, anti-HIV drugs like lopinavir and ritonavir and anti-viral drugs remdesivir and Favipiravir.
How does Favipiravir work against COVID-19?
Favipiravir directly acts on the RdRp catalytic site to prevent the virus from replicating in the cells and inhibiting the infection. It works specifically by blocking the RNA polymerase of the virus. It stops the virus from replicating by crippling the RNA polymerase enzyme. Without the enzyme, the virus cannot duplicate its genetic materials inside the host cell thereby inhibiting it from infecting other cells.
The potential of Favipiravir against coronavirus
Favipiravir may potentially have an antiviral effect on the new coronavirus given the way it works on the influenza virus. With evidence from Chinese authorities, this drug shows very good clinical results for COVID-19 patients. It has a high degree of safety and is clearly an effective treatment for coronavirus disease. Based on the clinical trials conducted both in China and Japan, Favipiravir has the ability to shorten the recovery time of patients infected with the coronavirus disease, with mild to moderate symptoms from 11 days to four days. Patients given the therapy tested negative after around four days of treatment compared to those who were not treated. It also seemed to shorten the duration of fever from an average of 4.3 days to 2.5 days. Patients taking Favipiravir also showed significant improvement in chest imaging. However, in the clinical trials conducted, Favipiravir seems less effective in patients with severe symptoms.
How to take Favipiravir in treating COVID-19?
Patients under the clinical trial were given 1,600mg of Favipiravir twice a day in two separate doses with inhaled interferon on day one. On day two, the doses were reduced to 600mg two times a day with inhaled interferon.