Metabolic differences between Asian and Caucasian patients on clozapine treatment.
OBJECTIVE
To establish if there are ethnic differences in the various metabolic disturbances that are common with clozapine treatment.


METHODS
Forty subjects (20 Asians and 20 Caucasians) with a diagnosis of schizophrenia were recruited for the study. Clozapine blood levels as well as fasting blood glucose, lipid levels, and liver function tests were established. Other clinical parameters such as blood pressure and Body Mass Index (BMI) were recorded for each patient.


RESULTS
The mean clozapine dose was significantly higher in the Caucasian subjects (432.5+/-194.7 mg) as compared to the Asian subjects (175.6+/-106.9 mg) (p<0.001) while the mean weight-corrected dose for Asian patients was lower (3.0+/-1.9 and 5.0+/-2.1 mg/kg, respectively, p=0.005). There were, however, no ethnic differences in the mean plasma clozapine concentration (415.3+/-185.8 ng/ml in Caucasians and 417.1+/-290.8 ng/ml in Asians). BMI were significantly higher in Caucasians, as were the number of subjects with hypertension; levels of hepatic enzymes were higher in the Asian group.


CONCLUSIONS
Not only are there pharmacokinetic differences between Asian and Caucasian patients receiving clozapine, but there may also be differential emergence of certain metabolic abnormalities like hypertension and weight gain in these two ethnic groups. However, the effects of life style including diet and exercise cannot be excluded.
Subramaniam
Mythily
M
Institute of Mental Health and Woodbridge Hospital, Singapore, and Department of Psychiatry, University of Melbourne, Richmond, Australia. Mythily@imh.com.sg
Ng
Chee
C
Chong
Siow-Ann
SA
Mahendran
Rathi
R
Lambert
Tim
T
Pek
Elaine
E
Huak
Chan Yiong
CY
D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000493:pharmacokinetics*; D044466:Asian People; D001219:Aspartate Aminotransferases / Q000097:blood; D001663:Bilirubin / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D003024:Clozapine / Q000009:adverse effects / Q000493:pharmacokinetics*; D004032:Diet; D005006:Ethnicity; D005260:Female; D006801:Humans; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D014280:Triglycerides / Q000097:blood; D044465:White People
D014150:Antipsychotic Agents; D001786:Blood Glucose; D014280:Triglycerides; D002784:Cholesterol; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D003024:Clozapine; D001663:Bilirubin