Investigation of the safety of oseltamivir in infants less than 1 year of age infected with influenza, 2003/2004 season in Japan

Abstract

The aim of this study was to investigate the safety of oselta mivir in Japanese patients less than 1 year of age infected with influenza A or B. The study was retrospective and surveil lance forms were used to collect safety data for all influenza -infected infants administered oseltamivir during the 2003/2004 infl uenza season in the 157 participating facilities. Seven hundred seventy one children (mean age 272 ± 74.86 days, range 15 to 366 days) were treated with oseltamivir at a mean dose of 3.84 ± 0.51 mg/kg/day (range 1.85 to 6.25 mg). The incidence of adverse events (AEs) and adverse drug reactions (ADRs) was 5.3% (41 of 771 patients) and 3.2% (25 of 771 patients), respectively. Among the 51 AEs reported in 41 patients, gastrointestinal disorders were the most frequent (2.5% (19 of 771 patients)), with diarrhoea (n = 15) and vomiting (n = 6). Gastrointestinal disorders were also the most frequently reported ADRs, with diarrhoea (n = 13) and vomiting (n = 5). Four patients with afebrile or febrile convulsions (n = 3) and respiratory failure (n = 1) with fatal outcome were probably caused by serious AEs. Influenza infection accompanying with high fever is well known to cause these events in infants. This paper has concluded effective treatment of oseltamivir administration in influenza-infe cted infants less than 1 year of age; and it does not raise any s afety concerns. Therefore, a further prospective survey to eluci date the ADRs should be carried out.