Pharmacokinetics and pharmacodynamics of a 0.1 mg/kg dose of cisatracurium besylate in children during N2O/O2/propofol anesthesia.

Abstract

We studied the pharmacokinetics and pharmacodynamics of cisatracurium in 9 children (mean weight, 17.1 kg) aged 1-6 yr (mean, 3.75 yr) during propofol-nitrous oxide anesthesia. Neuromuscular monitoring was performed. Venous samples were taken before injection of a 0.1 mg/kg dose of cisatracurium and then at 2, 5, 10, 30, 60, 90, and 120 min. Cisatracurium plasma concentrations were determined by high performance liquid chromatography. Onset time was 2.5 +/- 0.8 min, recovery to 25% of baseline twitch height was 37.6 +/- 10.2 min, and the 25%-75% recovery index was 10.9 +/- 3.7 min. Distribution and elimination half-lives were 3.5 +/- 0.9 min and 22.9 +/- 4.5 min, respectively. Steady-state volume of distribution (0.207 +/- 0.031 L/kg) and total body clearance (6.8 +/- 0.7 mL/min/kg) were significantly larger than those published for adults. Pharmacodynamic results were comparable to those obtained in pediatric studies during halothane or opioid anesthesia with the exception of a longer recovery to 25% baseline. Although the plasma-effect compartment equilibration rate constant was twofold faster (0.115 +/- 0.025 min(-1)) than that published for cisatracurium in adults, the effect compartment concentration corresponding to 50% block was similar (129 +/- 27 ng/mL).