Favipiravir (originally known as T-705) is an orally administered novel anti-viral compound with a unique mechanism of action that is active against a wide range of RNA-based viruses in laboratory tests. In March of 2012 the company received a $138.5 million contract from The Department of Defense’s (DOD) Joint Project Manager Transformational Medical Technologies (JPM-TMT) to further develop favipiravir against multiple influenza viruses.
Results from a Phase 2 trial showed that twice daily dosing of T-705a demonstrated statistically significant decreases in time to alleviation of each of the six influenza symptoms. In addition, subjects receiving T-705a cleared the virus statistically significantly more quickly compared to placebo. T-705a appears safe and well tolerated with no serious adverse events reported during this study.
Enrollment has recently been completed in two FAVOR favipiravir Phase 3 studies in adults with uncomplicated influenza. The two studies enrolled 2,021 patients in participating clinics and practices in the Americas, Europe, Australia, New Zealand and South Africa.
This is the “one drug, many bugs” approach.
The one-drug-one-bug paradigm of drug development is insufficient to meet the threat of emerging and re-emerging viral pathogens. This underscores the need for broad-spectrum antivirals that act on multiple viruses based on some commonality in their viral life cycle, rather than on specific viral proteins.
Broad-spectrum antivirals represent a gold-standard in the development of effective countermeasures for treating a wide range of viral diseases. Broad-spectrum antiviral drugs are preferred because they have the capacity to treat a range of viral illnesses rather than just one.
Drugs with broad-spectrum antiviral activities may significantly simplify the treatment based on the idea that different viruses utilize common host cell factors for their multiplication. Thus, if one would be able to block these interactions with a single drug, then this drug could limit several different viruses.
Favipiravir has been shown to be effective at treating cells infected with a surprisingly broad range of RNA viruses other than influenza. There are commonalities among RNA polymerases carried by other viruses, which may explain why favipiravir is effective against a broad spectrum of RNA viruses.
Favipiravir has been tested in infected cells and has been shown to be effective against virus from ten viral families as indicated on the diagram by the lightning bolts.
Mechanism of Action
Favipiravir inhibits synthesis of new viral RNA strands by the enzyme influenza RNA polymerase.
The drug is able to achieve this because cell and viral enzymes mistake favipiravir for a purine building
block of RNA and incorporate it into new growing strands, which affects production of progeny virus.
This is a different mechanism of action than what is used by influenza drugs currently on the market.
It is beneficial to have a variety of drugs available that act on different pathways in case a new strain emerges
that is resistant to approved drugs.