OBJECTIVE To study the effect of thiopental on pharmacokinetics of propofol in patients undergoing general anesthesia.METHODS 16 Patients undergoing general anesthesia were divided into 2 groups randomly.After intravenous administration of propofol 2 mg·kg-1 or 1% propofol and 2.5% thiopental in a ratio of 1:1 volume mixture,the serum concentrations of propofol were measured by high performance liquid chromatography.The pharmacokinetic parameters of propofol were estimated by 3P97 program.RESULTS The serum concentration-time profiles of propofol were discribed by a three compartment model.The pharmacokinetic parameters for two groups were as follows:t1/2α(0.8±0.4) and(0.7±0.3)min,t1/2β(10.2±15.6) and(6.5±5.0) min,t1/2γ(113.0±47.2) and(159.0±82.5) min,Vc(0.055±0.022) and(0.052±0.041) L·kg-1,CL(17.4±4.5) and(15.5±8.3) mL·h-1·kg-1,AUC(108.92±31.68) and(88.84±59.08) mg·min·L-1,respectively.CONCLUSION No significant differences were found among the main pharmacokinetic parameters in two groups,which is in good accordance with that of the literature reports.