Comparison of pharmacokinetics and pharmacodynamics of rocuronium infusion in adults and children

ABSTRACT

This study compared the pharmacokinetics and pharmacokinetic-dynamic relationship of rocuronium in children and adults, we studied 10 children [4-8 years] and 10 adults [20-40 years] ASA I and II underwent surgical operation in Kasr-El-Aini hospital. After induction with thiopentone [2-6 mg/kg], fentanyl 5-10 Hg/kg, infusion of rocuronium 0.09 mg/kg/min. in children group and 0.1 mg/kg/min. in the adults group. The infusion was given over +/- 5 minutes. The patients were monitored with the EMG of the adductor pollicis muscle. When neuromuscular block reached 85% endotracheal intubation, and then mechanical ventilation was started Maintenance of anesthesia with isoflurane 0.5- 1%, O[2]/NO[2] 50% in both groups. Arterial sample were obtained over 240 min./ Plasma concentrations were measured by HpLc. pharmacokinetic-dynamic variables were calculated using sheiner model, and the Hill equation. Statistical analysis was performed using the Mann-Whitney U test [p < 0.05]. The mean administered dose of rocuronium infusion was 0.65 +/- 0.09 mg/kg/hour in adults group and 0.35 +/- 0.1 mg/kg/hour in children group. Children differed from adults in plasma clearance 5.2 +/- 0.043 versus 7.65 +/- 1.05 ml/min./kg in adults group, distribution volume at steady state 220 +/- 20 ml/kg in children group and 168+50 ml/kg in adults group, mean residence time 50.5 +/- 9.0 [min.] in children group and 26 +/- 9.0 [min.] in adults group, concentration in effect compartment at 50% block 1.19 +/- 0.4 mg/liter in children group and 1.3 +/- 0.3 mg/liter in adults group, calculated mean ED[90] values were 0.345 +/- 0.077 in adults group, 0.25 +/- 0.067 in children group. The time course of neuromuscular block did not differ. The study concluded that infusion of rocuronium has different pharmacokinetic-dynamic in both adults and children, but it can be safely used in children especially when the infused dose adjusted by using the EMG