Pharmacokinetics of midazolam in critically ill pediatric patients.

ABSTRACT

Midazolam is frequently used to produce sedation in critically ill pediatric patients. We studied the pharmacokinetics of midazolam in 22 patients (age 8 days to 16 years). The intravenous infusion rate to produce sedation ranged from 49-385 mcg/kg/hr. The blood samples were obtained at steady-state and midazolam was measured by gas chromatography with electron capture. The steady-state plasma concentrations of midazolam ranged from 49-385 ng/mL. The total clearance, apparent volume of distribution, and elimination half-life ranged from 0.1-3.1 L/kg/hr, 0.2-3.5 L/kg, and 0.3-10.9 hours, respectively. The marked interpatient variability in pharmacokinetics explains in part, the substantial variation in dosage requirements of midazolam to produce sedation in critically ill pediatric patients.