The pharmacokinetics of ketamine were studied in 8 preschool children,aged 3.5～6 years. The ketamine was administrated by I. V. infusion at a dose of 3mg?kg~(-1) in one hour constantly. The plasma concentrations of ketamine were measured by high performance liquid chromatography. The disposition of intravenous infusion with ketamine could be described by two-compartment open model, and the variables of pharmacokinetics of ketamine were as follows: T_(1/2?)=0.15?0.04 hours,T_(1/2?)=2.84?0.44 hours,Cl=0.34?0.06L?kg~(-1)?h~(-1), AUC=9.21?1.00mg/L?h, and V_d=0.66?0.29 L?kg~(-1). This suggests that intravenous infusion of ketamine at 3mg?kg~(-1)?h~(-1) is safe for the maintenance of general anesthesia in preschool children, attention must he paid to the children anesthetized with long period of ketamine infusion because recovery may be delayed due to the prolonged elimination half-life.

Objective: To determine the influence of ?-hydroxybutyric sodium (7-OH)on the pharmacokinetics of ketamine infusion in preschool children. Method: Sixteen patients were randomly assigned to group Ⅱ (Ketamine) and group Ⅱ (Ketamine plus ?-OH). After trachea intubation,0.05% ketamine was infused in both groups at 3mg?kg~(-1)?h~(-1) and ?-OH 125mg?kg~(-1) only in group Ⅱ. The plasma concentration of ketamine was measured using high performance liquid chromatography. Pharmacokinetic parameters were calculated using 3P_(87) software composed by Chinese Pharmacologic Society. Result: In both groups,pharmaeokinetics could be descrided as two-compartment open model. The T_(1/2)? and the Cl differ between group Ⅰ and group Ⅱ (P