Clozapine Dosage and Blood Concentrations of Korean Adult Schizophrenic Patients

Kim, Chul Eung; Lee, Yoon Hee; Lee, Kyung Hoon; Kang, Min Hee

Abstract

OBJECTIVES
The present study aimed to determine the optimal clozapine dosage in Korean adult schizophrenic patients, and to measure the blood levels of clozapine and its major metabolites.
METHODS
Thirty schizophrenic patients, who have undertaken clozapine over 1 year, were recruited in this study. We investigated the clozapine dose at different times(2, 4, 8, 12, 24, 52 weeks) during the course of treatment with clozapine and we measured the blood level of clozapine and its major metabolites, N-desmethylclozapine and clozapine-N-oxide by using high performance liquid chroma-tography(HPLC).
RESULTS
The average dosages of clozapine at 2, 4, 8, 12, 24, 52 weeks were 22.5(+/-92.2), 330.0 (+/-139.2), 344.8(+/-80.6), 327.5(+/-93.4), 288.3(+/-118.5), 239.3(+/-112.3)mg/day respectively. The average clozapine dose of male schizophrenics was significantly higher than that of female schizo-phrenics after 8 weeks during the course of treatment. But there were no significant differences in blood level of clozapine and its major metabolites between genders in same dosage of clozapine. The average dose of clozapine in smokers was slightly higher than non-smokers, but there was no statistical significance. The blood levels of clozapine and its major metabolites was significantly correlated with the total dose of clozapine.
CONCLUSION
The average clozapine dose of Korean adult schizophrenics was lower than that of reported Caucasian data, and to reach the known therapeutic clozapine blood level above 350-400 ng/ml, we need 300-400mg/day of clozapine.