Abstract: AIM: To establish a method for determination of serum concentrations of quetiapine fumarate inPatients with schizophrenia of different doses and to study its relationshiPwith clinical response.METHODS: A HPLC method was used to determine serum concentrations of quetiapine fumarate in 76Patients with schizophrenia before or after 2,4,6-week treatment and its therapeutic efficacies were measured by BPRS.RESULTS: The standard curve waslinearwithin the concentration range of 0.05 -0.5 mg·L^-1of quetiapine fumarate in serum(r=0.9850).The serum concentrations of quetiapine fumarate wereProportionally increased with the daily dose of 50 -450 mg,but there was no significant correlation with age and sex.The optimal range estimated was 0.126 -0.350 mg·L^-1.CONCLUSION: The assay is simple,precise and suitable for therapeutic monitoring of quetiapine fumarate and the optimal concentration window is 0.126 -0.350 mg·L^-1in treatment ofPatients with schizophrenia.

Key words: pharmacodynamics, quetiapine fumarate, serum drug concentration, schizophrenia, chromatography, HPLC