Millions of people have succumbed to the disease caused by the SARS-CoV-2 virus responsible for the covid-19 pandemic. As the disease is still affecting thousands every month, scientists are looking for various treatment parameters to reduce the risk of death from covid-19 disease.
Although the vaccination program is running successfully all around the world, the efficacy of the vaccines is questionable in controlling the outbreak. In the meanwhile, doctors are trying to find the effect of various antiviral medications like Favipiravir in controlling the severity of symptoms caused by the SARS-CoV-2 virus.
After Favipiravir (ฟาวิพิราเวียร์, term in Thai), another antiviral drug, Molnupiravir has shown satisfactory results in the phase 3 trials reducing the risk of death by 50% in mild-moderate cases. This drug is sold by S.M. Pharmaceutical Company Limited in Bangkok. They are a premium organization selling the original formulation of Acetylcysteine which is used as a paracetamol antidote and in treating thick mucus in patients suffering from chronic respiratory diseases like COPD and bronchitis.
How does Favipiravir work?
Upon administration, this drug undergoes phosphoribosylation to get converted into the active form of the drug which then produces the following effects in the human body:
- By acting as a substrate for the RdRp enzyme, it inhibits the process of viral protein synthesis.
- Also, it prevents any further extension of the viral RNA by getting incorporated in it.
Thus, it is a broad-spectrum antiviral drug that has also shown virucidal activity against the influenza virus in in-vitro studies.
It is used for the treatment of many forms of influenza virus, Ebola virus, and other RNA viruses like yellow fever virus.
Role of Favipiravir in treating infection caused by SARS-CoV-2
In theory, this drug can be effective against the virus as it binds to the RdRp enzyme of SARS-CoV-2 thus inhibiting its multiplication. Because the active form of the drug acts as a mutagen, it can flee the repair machinery of coronavirus. Thus, viral replication and transcription are both inhibited.
However, the dosage at which this effect can be achieved is unclear but it is still given at a dose of 1800mg twice daily for the first day and 800mg twice daily for subsequent days (2-14 days course).
According to a study conducted in China, patients with moderate Covid-19 disease showed improvement in clinical symptoms by day 7 of taking Favipiravir. The viral clearance time reduced in these patients to 4-9 days which is commonly observed as 8-14 days otherwise. Chest CT reports of these also showed faster improvements than the control group.
Some of the side effects that this drug can cause are:
- Decrease in the count of neutrophils.
- Embryotoxicity, and hence, its use is prohibited in pregnant women.
The use of the drug is also contraindicated in patients suffering from hepatic or renal impairment and those with a personal medical history of gout.
Favipiravir is being commonly given to many covid-19 patients with mild to moderate disease across the world and is the first oral drug that has got approval for this purpose. With a good safety profile, broad-spectrum activity, and absence of resistance, this drug is a promising candidate for treating coronavirus patients.