Two-stage analysis of pharmacokinetics of sufentanil administered by target-controlled infusion in Chinese patients.

Background Sufentanil is a suitable choice for target-controlled infusion (TCI) because of its shorter context-sensitive half-time. The current study was to estimate the pharmacokinetics of sufentanil TCI in Chinese patients using the two-stage analysis. Methods Twelve adult patients with American Society of Anesthesiologists (ASA) physical status I or II undergoing elective surgery under general anesthesia were included. Anesthesia was induced with propofol, rocuronium and sufentanil administered by TCI lasting for 30 minutes, with target effect-site concentration of sufentanil 4 or 6 ng/ml. Frequent arterial blood samples (1.5 ml) were taken during and up to 24 hours after sufentanil TCI. Before the end of surgery, another arterial blood sample (1.0 ml) was drawn for the blood-gas analysis. Plasma sufentanil concentrations were determined by liquid chromatography-tandem mass spectrometry (limit of quantitation was 5 pg/ml). The data were analyzed with the two-stage approach, linear regression and correlation analysis. Results The pharmacokinetics of sufentanil TCI were adequately described by a three-compartment model. The variables were derived as follows: the volume of central compartment (V 1 ) was 5.4 L, volume of distribution at steady-state (Vdss) was 222.6 L, metabolic clearance (Cl 1 ) was 0.84 Umin and elimination half-life (t 1/2 Y) was 389 minutes. Patients' age, gender and PaCO 2 correlated significantly with the pharmacokinetic parameters. The Vdss, volume of slowly equilibrating compartment (V 3 ) and h 1/2 Y increased, and rapid distribution clearance (Cl 2 ) decreased with increasing patient age. Male patients had larger values of Vdss, volume of rapidly equilibrating compartment (V 2 ) and V 3 than female patients. The Vdss and V 3 increased with higher PaCO 2 values. There were no significant correlations between the pharmacokinetic variables and body weight, height, lean body mass, plasma albumin, sufentanil dose, duration of surgery, pH or base excess of blood (BE-B). Conclusions The pharmacokinetics of sufentanil TCI in Chinese patients can be optimally described by a three-compartment model. The pharmacokinetic analysis technique may affect the pharmacokinetic parameters and correlations.