High levels and safety of oseltamivir carboxylate plasma concentrations after nasogastric administration in critically ill children in a pediatric intensive care unit.

During the 2009 H1N1 influenza pandemics, the concentrations of oseltamivir (O) and its active metabolite (oseltamivir carboxylate [OC]) were determined in 11 children (1 month to 16 years of age) admitted to intensive care units for presumed severe H1N1 infection. They received oseltamivir phosphate (OP) nasogastrically at doses between 1.5 and 6.8 mg/kg of body weight. High OC concentrations were found, with a mean level of 678 ± 535 μg/liter. The mean OP concentration was 27 ± 52 μg/liter. No marked side effect was reported.