Open-label study of the safety, pharmacokinetics, and effectiveness of a 2 mg/kg dose of baloxavir marboxil 2% granules in children <20 kg with influenza.

Abstract Introduction Baloxavir marboxil is an oral anti-influenza drug with demonstrated safety and efficacy in pediatric patients when a 2% granules formulation is administered at 1 mg/kg. This study assessed safety, effectiveness, and pharmacokinetics of a higher dose (2 mg/kg) of baloxavir marboxil 2% granules in pediatric patients weighing Methods This multicenter, open-label, noncontrolled study was conducted at 15 sites in Japan (January 2019–March 2020; JapicCTI-194577). Patients aged Results 45 patients, all aged ≤6 years, were enrolled. Adverse events were reported in 24 (53.3%) patients, most commonly nasopharyngitis, diarrhea, and upper respiratory tract infection. Median (95% confidence interval [CI]) TTIA was 37.8 (27.5–46.7) hours; median (95% CI) time to resolution of fever was 22.0 (20.2–28.6) hours. A >4 log decrease in mean viral titer occurred at day 2 and a subsequent temporary 1–2 log increase in patients with influenza A(H3N2) and B. Treatment-emergent PA/I38X-substituted virus was detected in 16/39 (41.0%) patients, but no prolonged TTIA or time to resolution of fever was associated with its presence. Conclusions Baloxavir granules administered at 2 mg/kg in children