OBJECTIVE:To study the pharmacokinetic characters of clozapine and the feasibility of regimen obtained from calculation of pharmacokinetic parameters. METHODS:In the active group, 30 patients who have been fasted for 12h were treated with a single dose of 75mg clozapine, their plasma drug level were measured at 0.5,2,5,8,12, and 32 h respectively and then they were treated with a regimen calculated from the pharmacokinetic parameters. In the control group, patients were treated with clozapine by routine approach and their plasma drug level were measured after 1 month treatment and the scales of BPRS, SANS, and TESS were evaluated before treatment and 1, 2, and 3 months after treatment .RESULTS:The t 1/2 of absorbtive phase, t 1/2 of clearance phase and clearance rate were 0.68,13.09,and 0.057 L/h respectively . Significant difference in drug peak level has been revealed among patients receiving the same dose of drug and the difference may be as high as 7 folds. The post treatment total BPRS scores in active group were significantly reduced ( P <0.05) but no obvious reduction in control group. No significant difference in pre and post treatment SANS existed in both active and control groups. In active group, the post treatment total TESS scores were significantly lower than that of pre treatment.CONCLUSION:With the help of pharmacokinetic parameters the efficacy, the incidence of side effects and the rational use of antipsychotic agent may be greatly improved.