Moxalactam pharmacokinetics in children

We measured the serum concentrations of moxalactam in 10 children receiving antibiotic prophylaxis for surgery and in 18 children treated for documented or suspected infections. Moxalactam was administered intravenously at a dose of 50 mg/kg every 8 h. After the first dose in 28 patients, mean moxalactam concentrations 5 min, 30 min, 2 h, and 8 h after infusion were 257, 177, 82.2, and 17.5 micrograms/ml, respectively. The mean half-life (T 1/2) was 2.44 h (range: 0.55 to 7.96 h). The mean distribution volume (VD) was 0.30 liters per kg. No significant accumulation was observed with multiple doses. Prophylactic and therapeutic groups had similar serum levels, T 1/2, and VD. The five infants less than 1 year of age had a lower mean 30-min level (P less than 0.01), larger VD (P less than 0.001) and longer T 1/2 (P less than 0.025) than the children older than 1 year. A dose of 50 mg/kg produced 30-min levels in excess of 64 microgram/ml in all patients studied, but 8-h trough levels were below the minimal inhibitory concentrations breakpoint of 17 mg/ml in 32% of patients.