Oseltamivir

Oseltamivir, a selective neuraminidase enzyme inhibitor, has gained worldwide attention in view of Influenza A (H1N1) pandemic. It is one of the most important drugs effective against the novel influenza virus. Oseltamivir is used for the treatment of uncomplicated acute illness due to influenza infection. Early initiation of treatment with the drug provides greater clinical benefits. The drug can also be effectively used for prophylaxis. Oseltamivir is readily absorbed from the gastrointestinal tract and is converted to the active metabolite-oseltamivir carboxylate, which has a wider distribution in the body. Oseltamivir carboxylate is eliminated in the urine with a half-life of 6-10 h. The drug is generally well-tolerated and does not have many clinically significant drug interactions. Nausea and vomiting are the commonest adverse effects associated with its use. The standard adult dose for treatment is 75 mg twice a day for five days and the dose for prophylaxis is 75 mg once daily for at least seven days following contact with an infected individual. The dose needs to be adjusted in patients with renal failure but no adjustments are required in patients with hepatic impairment. Although most of the influenza virus strains are sensitive to oseltamivir, development of drug resistance may limit the clinical utility of the drug in the future.