Pharmacokinetics and Pharmacodynamics of a 0.1 mg/kg Dose of Cisatracurium Besylate in Children During N2O/O2/Propofol Anesthesia

In Brief 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). IMPLICATIONS: Cisatracurium was shown to provide safe muscle relaxation in children 1-6 yr old during propofol anesthesia by studying cisatracurium blood levels and depth of paralysis. Differences in pharmacokinetics/pharmacodynamics from adults highlight the need for pediatric studies to guide dosing and predict duration of action in children.