Favipiravir: An antiviral drug
Favipiravir is an antiviral drug. It acts against many viruses like influenza viruses type 1 to type 3 and also human Rhinovirus. Recently it has been found that it also acts against novel corona virus. It has been found to be useful in treatment of Covid-19 disease in some trials. This drug was developed by Toyama chemical from Japan. Glenmark pharma has got approval from India’s drug regulator for manufacturing and marketing this drug in India where currently the Covid-19 cases are increasing day by day. This drug was found useful reducing the viral load in covid-19 disease patients in 4 days significantly. It has been found to be useful in mild to moderate disease.
How does favipiravir works?
Favipiravir is an antiviral agent. It halts the replication of novel corona virus and other virus. These viruses when infect the host and gains entry in to the cells they use the host cell machinery for their replication. During this process various enzymes are needed. Before the replication of the virus the RNA the nuclic acid material of the virus needs to be replicated. This RNA carries the code for replication. It uses host cell machinery to make its new copies. Additionally it also carries the code to produce other important structural proteins in the virus. After producing RNA copies in huge numbers the host ribosomes are used to read the code on RNA. This code directs the machinery to produce other components of the virus. Then the assembly of the RNA and components produced by the machinery is joined to form the new virus copies. One the most important enzyme during this process is RNA polymerase. This enzyme while replication of the RNA of virus, identifies necessary nuclic acids and combines it into the process to synthesize the RNA copy. Favipiravir when enters the host cell it is convcerted to its active form a phosphoribosyl form. This form is purine like in its function which is a nuclic acid. So viral RNA polymerase by mistake recognizes this activated form of favipiravir as a purine. This molecules get incorporated in the viral RNA. Thus faulty copies of RNA are produced. As we discussed earlier, that for viral replication and assembly the code, the information is present in the viral RNA. In short favipiravir damages that information. They faulty RNA copies and in turn faulty virus which is not viable and not harmful is produced. As this drug applies brake to viral replication the viral load in infected person dicreases in span of few hours.
According to press release by Glenmark pharma, the drug regulator of India has granted approval for manufacturing and marketing of this drug in India by Glenmark Pharma.Further they have clarified:
- · Manufacturing and marketing approval granted as part of accelerated approval process, considering the emergency situation of the COVID-19 outbreak in India.
- · The approval’s restricted use entails responsible medication use where every patient must have signed informed consent before treatment initiation.
- Favipiravir shows clinical improvements of up to 88% in COVID-19, with rapid reduction in viral load by 4 days.
- Clinical improvement noted across age groups 20 to >90 years, including in patients with co-morbid conditions like diabetes and heart disease suffering from mild to moderate COVID-19.
- Glenmark to market the antiviral under the brand name ‘FabiFlu®’.
- The benefit of using favipiravir is this drug can be given orally in mild to moderate cases of Covid-19 disease.
Most patients exhibiting mild to moderate symptoms can benefit from FabiFlu® use. The drug will be available as a prescription-based medication for INR 103/tablet, with recommended dose being 1800 mg twice daily on day 1, followed by 800 mg twice daily up to day 14, according to press release by Glenmark pharma.Favipiravir is approved in Japan since 2014 for the treatment of novel or re-emerging influenza virus infections. It has a unique mechanism of action: it is converted into an active phosphoribosylated form (favipiravir-RTP) in cells and recognized as a substrate by viral RNA polymerase, thereby inhibiting RNA polymerase activity.