Oseltamivir dose may be appropriate for premature infants

Acosta EP. J Infect Dis. 2010;202:563-566.

Premature infants may benefit most from a 1 mg/kg dose of oseltamivir when administered twice daily as prophylaxis, study data suggest.

Researchers from the University of Alabama at Birmingham, School of Medicine, and Women’s Hospital of Greensboro, N.C., conducted a trial in which they had a standing protocol to collect blood for pharmacokinetic analysis from infants in a neonatal ICU.

During the study, a health care worker was found to have 2009 pandemic influenza A (H1N1). The neonatologist opted to administer a 1.5 mg/kg dose of oseltamivir twice daily to the exposed infants. The prophylaxis lasted 10 days.

Twenty of 32 exposed infants were included in the analysis, according to the researchers, with a median gestational age of 27.5 weeks, median weight of 1,684 g and median chronological age at time of sample collection of 2.5 weeks. The median dose received was 1.79 mg/kg, and the median number of doses received was 11 at time of sampling.

No infant developed influenza, and no drug-related adverse events were observed during therapy.

Results also demonstrated that, although preterm infants received a fourfold lower dose of oseltamivir on average than term infants, their oseltamivir carboxylate exposures were two times higher. The researchers said these data indicate that “use of a mg/kg approach” may be more effective than an age-based dosing regimen.

“These modeled results, noncompartmental analysis, and mean raw concentrations suggest an oseltamivir dose of approximately 1.0 mg/kg/dose (twice daily) should achieve oseltamivir carboxylate exposures in premature neonates (less than 38 weeks) comparable to that in infants and young children receiving 3 mg/kg/dose twice daily,” the researchers wrote.

They noted, however, that the study data was limited, and more research is required to establish the optimal dose of oseltamivir in this population.