indication

For the prevention and treatment of influenza A and B.

pharmacology

Zanamivir, an antiviral agent, is a neuraminidase inhibitor indicated for treatment of uncomplicated acute illness due to influenza A and B virus in adults and pediatric patients 7 years and older who have been symptomatic for no more than 2 days. Zanamivir has also been shown to significantly inhibit the human sialidases NEU3 and NEU2 in the micromolar range (Ki 3.7 +/-0.48 and 12.9+/-0.07 microM, respectively), which could account for some of the rare side effects of zanamivir.

mechanism of action

The proposed mechanism of action of zanamivir is via inhibition of influenza virus neuraminidase with the possibility of alteration of virus particle aggregation and release. By binding and inhibiting the neuraminidase protein, the drug renders the influenza virus unable to escape its host cell and infect others.

biotransformation

Not metabolized

absorption

Absolute bioavailability is very low following oral administration (2%). Following oral inhalation, bioavailability is 4% to 17%.

half life

2.5-5.1 hours

route of elimination

It is excreted unchanged in the urine with excretion of a single dose completed within 24 hours. Unabsorbed drug is excreted in the feces.Zanamivir is renally excreted as unchanged drug.