Aim:To study the multiple dose clinical pharmacokinetics of risperidone and itsmain active metabolite,9-hydroxyrisperidone,in Chinese female patients withschizophrenia.Methods:The subjects were 23 Chinese female inpatients aged18-65 years who met the CCMD-Ⅲ(third revision of the Chinese Criteria of Men-tal Disorders)criteria for schizophrenia.Subjects were tested after 17 d of treat-ment with 2 mg risperidone twice dally.Plasma concentrations of risperidone and9-hydroxy-risperidone were assayed by using validated high performance liquidchromatography-mass spectrometry(HPLC-MS)methods.Results:Risperidonewas rapidly absorbed(T_(max) was 1.6 h)and its T_(1/2) in plasma was short(3.2 h).9-hydroxy-risperidone was quickly metabolized from the parent drug with a meanT_(max) of 2.5 h.It had a long half-life of 24.7 h.The C_(av)~(ss) of risperidone and 9-hydroxy-risperidone were 36.9±33.1 and 110.6±30.5 μg·h·L~(-1),respectively,and the AUC_(0-12)~(ss)were 443.2+397.4 and 1327.2±402.3 μg·h·L~(-1),respectively.CL/F and V/F ofrisperidone were 8.7±6.2 L/h and 34.1±24.3 L,respectively.Interindividual varia-tions for pharmacokinetic parameters were quite large for risperidone.All 23 sub-jects experienced high prolactin levels when treated with risperidone.Howeverthere was no correlation between prolactin level and the concentration ofrisperidone,9-hydroxy-risperidone,or the active moiety.Conclusion:Risperidoneshowed large interindividual variations in pharmacokinetics.Administration ofrisperidone resulted in high serum prolactin levels.The results indicate that sys-temic exposure to risperidone and 9-hydroxy-risperidone in female Chinese schizo-phrenic patients is higher relative to published data for white Caucasian patients.Larger studies regarding the PK/PD relationship may be required to develop areasonable clinical dosage regimen for Chinese female patients. Aim: To study the multiple dose clinical pharmacokinetics of risperidone and its main active metabolite, 9-hydroxyrisperidone, in Chinese female patients with schizophrenia. Methods: The subjects were 23 Chinese female inpatients aged 18-65 years who met the CCMD-III (third revision of the Chinese Criteria of Men-tal Disorders) criteria for schizophrenia. Subjects were tested after 17 d of treat-ment with 2 mg risperidone twice dally. Plasma concentrations of risperidone and 9-hydroxy-risperidone were assayed by using validated high performance liquid chromatography-mass spectrometry ( HPLC-MS) .Results: Risperidonewas rapidly absorbed (T_ (max) was 1.6 h) and its T_ (1/2) in plasma was short (3.2 h) .9-hydroxy-risperidone was quickly metabolized from the parent drug with a meanT max of 2.5 h.It had a long half-life of 24.7 h.The C_ (av) ~ (ss) of risperidone and 9-hydroxy-risperidone were 36.9 ± 33.1 and 110.6 ± 30.5 μg.h ~ (-1), respectively, and the AUC_ (0-12) ~ (ss) were 443.2 + 397.4 and 1327.2 ± 402.3 μ g · h · L -1, respectively.CL / F and V / F ofrisperidone were 8.7 ± 6.2 L / h and 34.1 ± 24.3 L, respectively.Interindividual varia- tions for pharmacokinetic parameters were quite large for risperidone. All 23 sub-jects experienced high prolactin levels when treated with risperidone. Howevehere was no correlation between prolactin level and the concentration ofrisperidone, 9-hydroxy-risperidone, or the active moiety. Conflux: Risperidoneshowed large interindividual variations in pharmacokinetics. Administration ofrisperidone resulted in high serum prolactin levels. The results indicate that sys-temic exposure to risperidone and 9-hydroxy-risperidone in female Chinese schizo-phrenic patients is higher relative to published data for white Caucasian patients. Larger studies regarding the PK / PD relationship may be required to develop areasonable clinical dosage regimen for Chinese female patients.