Products
Favipiravir is approved in Japan in the form of film-coated tablets (Avigan).
Structure and properties
Favipiravir (C5H4FN3O2, Mr = 157.1 g/mol) is a fluorinated pyrazine carboxamide derivative. It is a prodrug that is biotransformed in cells to the active metabolite favipiravir-RTP (favipiravir-ribofuranosyl-5′-triphosphate), a purine nucleotide analog. Favipiravir exists as a white to slightly yellow powder and is sparingly soluble in water.
Effects
Favipiravir has antiviral properties with a broad spectrum of activity against RNA viruses. The effects are based on selective inhibition of the enzyme RNA-dependent RNA polymerase (RdRP, RNA polymerase) of viruses, which plays an essential role in RNA replication. This blocks viral replication. The half-life is approximately 5 hours.
Indications
For the treatment of influenza when new or dangerous strains of the virus occur against which other drugs are not effective. Favipiravir is used as an emergency medication when directed by the government. Off-Label Use:
- For the treatment of Ebola fever.
- In 2020, favipiravir was investigated for the treatment of covid-19.
Dosage
According to the professional information. The tablets are usually taken twice daily for 5 days. Therapy should be started as soon as possible after the onset of symptoms.
Contraindications
- Hypersensitivity
- Pregnancy: favipiravir has teratogenic (fetus-damaging) properties.
- Women without adequate contraception.
- In men receiving favipiravir, the active substance may be detected in semen. The corresponding precautionary measures in the technical information must be observed.
- Children
Full precautions can be found in the drug label.
Interactions
Favipiravir is metabolized by aldehyde oxidase and xanthine oxidase. CYP450 isozymes are not involved in metabolism.
Adverse effects
The most common potential adverse effects include increased uric acid levels, diarrhea, a decrease in neutrophils, and an increase in AST and ALT.
