Russia's approval of the antiviral drug Avifavir to treat COVID-19 is good news for India as it is based on an influenza medication already in advanced clinical trials here, say scientists.
Avifavir, described by its developers in Russia as perhaps the most promising anti COVID-19 drug in the world, is derived from Favipiravir.
Mumbai-based Glenmark Pharmaceuticals announced last week that Favipiravir is under phase 3 clinical trials -- the penultimate stage in drug testing -- in India.
Stating that Avifavir has shown high efficacy in treating patients with coronavirus during clinical trials, the Russian Direct Investment Fund (RDIF) on Monday said it will deliver 60,000 courses of the drug to Russian hospitals in June.
It also said Avifavir has become the first Favipiravir-based drug in the world to be approved for the treatment of COVID-19, it said. The close derivative link between Avifavir and Favipiravir is reason for hope in India too, said scientists here.
Favipiravir has anyway been in discussion and a point of interest in the recent past, said Arup Kumar Banerjee from the North Bengal Medical College and Hospital, Siliguri.
He noted that Favipiravir is available under the name of Avigan for influenza and is often recommended for viral infections such as bunyavirus, filovirus and arenavirus.
It is prescribed for severe fever with thrombocytopenia syndrome (SFTS), a viral hemorrhagic fever with high fatality rate and is effective against all strains of influenza viruses, Banerjee said.
Vaccine is important, so is antiviral. We need to develop both side by side. Today, if anybody comes up with a drug against COVID 19 irrespective of country or origin, it is a good news subject to validation of the same in large scale. Hence, the same applies to this derivative as well, he added.
Avifavir, developed by a joint venture between RDIF and ChemRar Group, is designed to disrupt the ability of the novel coronavirus to reproduce.
Avifavir is not only the first antiviral drug registered against coronavirus in Russia, but it is also perhaps the most promising anti Covid-19 drug in the world, RDIF CEO Kirill Dmitriev said in a statement.
The RDIF and the ChemRar Group last week announced that Avifavir has received a temporary registration certificate from the Russian Ministry of Health.
Avifavir is a drug that as per available information is being tested by Russia against COVID 19 and is based on Favipiravir, a drug that is known to have inhibitory function against RNA-dependent RNA polymerase (RdRP) activity of a virus, said virologist Upasana Ray.
RdRP is an essential protein encoded in the genes of RNA-containing viruses.
Favipiravir has been shown earlier to inhibit the influenza virus RNA-dependent RNA polymerase, Ray, senior scientist at CSIR-IICB in Kolkata said.
RNA polymerase is a viral enzyme that helps in replication or reproduction of the viral RNA, that is the genetic material. Hence, a drug that inhibits this activity would basically curb the functional multiplication of the virus, she explained.
Glenmark last week announced a new randomised study in India to test the combined efficacy of Favipiravir and another antiviral drug Umifenovir as a potential COVID-19 treatment strategy.
Glenmark also said that it is conducting Phase 3 clinical trials of Favipiravir as a COVID-19 therapy option with 150 patients, enrolled from nine leading government and private hospitals across the country.
So far, 30 patients have been randomised. The monotherapy phase 3 clinical trial results are expected by July or August 2020, the company said in a statement last week.
Glenmark said it is the first pharmaceutical company to receive approval from drug regulator Drug Controller General of India (DCGI) to conduct Favipiravir clinical trials against COVID-19 in India.
Favipiravir is an oral antiviral drug approved in Japan in 2014 for the treatment of novel or re-emerging influenza virus infections. It has a unique mechanism of action by which it inhibits viral replication or reproduction, it said.
Since it (Favipiravir) was earlier tested for influenza, they (researchers) could bypass initial toxicity tests etc. It was one of (hundreds) of clinical trials against SARS-COV-2. With preliminary data for the clinical trials looking positive they jumped on it, Durba Sengupta, from CSIR-National Chemical Laboratory in Pune, Maharashtra, said.
Sengupta said the drug acts on one of the main proteins that is responsible for RNA-replication.
He also injected a note of caution.
Till the clinical trial results are properly reported, it is difficult to say how effective it will be.
One has to be definitely cautious. First, it's not designed to target this particular virus, and it is RdRP, so the binding may be weaker than in influenza, Sengupta said.
Though it is unknown how the different viral strains will bind, she said it is one of the better options right now.
Another point, Sengupta noted, is that the drug's action is on the same target as the antiviral remdesivir, one of the top possible drug contenders for COVID-19.
I think several people thought that remdesvir would be quite promising - but it has been ambiguous so far. Getting robust clinical data in such short times is really tricky. It is really difficult to say without the actual clinical data and looking at the statistics, she added.
India's drug regulator has granted US pharma giant Gilead Sciences marketing authorisation for remdesivir for "restricted emergency use" on hospitalised COVID-19 patients in view of the crisis posed by the pandemic.
The approval process for remdesivir was accelerated in view of the emergency situation and the unmet need for medicines in light of the coronavirus outbreak, a source in the know of the developments told.