Peramivir, an intravenously administered neuraminidase inhibitor, may be used concomitantly with other influenza antivirals. Two studies were conducted to assess the potential for pharmacokinetic interactions of peramivir when coadministered with oseltamivir or rimantadine. Twenty-one healthy subjects were enrolled in each randomized, open-label, crossover study, and they received 1 intravenous dose of peramivir (600 mg), 1 oral dose of oseltamivir (75 mg) or rimantadine (100 mg), or a combination of peramivir with oseltamivir or rimantadine. Assessment of the 90% confidence interval for the geometric mean ratio of peramivir and oseltamivir carboxylate or rimantadine pharmacokinetic parameters showed no effect of oseltamivir or rimantadine on the pharmacokinetics of peramivir and no effect of peramivir on the pharmacokinetics of oseltamivir carboxylate or rimantadine. The drugs were well tolerated. These results suggest no reason to expect an effect of concomitant administration of oseltamivir or rimantadine on the safety profile of peramivir in patients with influenza.