Clinical Briefs-By Louis Kuritzky, MD

Efficacy and Safety of the Oral Neuraminidase Inhibitor Oseltamivir in Treating Acute Influenza

Agents that have been shown to be efficacious only against type A viruses have limited treatment of influenza. The recent introduction of neuraminidase inhibitors, which are effective against influenza A and influenza B viruses, offer new breadth of antiviral activity. This study evaluated a large population (n = 629) of nonimmunized adults who were subject to spontaneous acute febrile respiratory illness. Inclusion criteria included no influenza vaccination for at least 12 months, overall good health, symptoms present for less than 36 hours, and temperature of at least 38°.

Treatment consisted of oseltamivir (Tamiflu) 75 mg or 150 mg orally twice daily vs. placebo. Participants were allowed to use acetaminophen for symptomatic relief, and their use of acetaminophen was quantified.

Overall duration of illness was reduced by more than 30% with oseltamivir treatment. Similarly, symptom scores were significantly improved with active treatment so that median severity of illness decreased by approximately 40%. Improvements in symptoms were notable as early as 24 hours after administration of the first dose. Fever was significantly reduced within 24 hours also, and persons who received oseltamivir used approximately 20% less acetaminophen for symptom relief. There were no serious clinical or laboratory side effects seen, and the withdrawal rate was the same as or less than placebo.

Oseltamivir is effective and well tolerated in treatment of acute influenza A or B.

Treanor JJ, et al. JAMA 2000;283: 1016-1024.