Abstract
The aim of the present study was to determine the prescribing practice for clozapine
(CAS 5786-21-0) as well as the plasma levels of clozapine and its main metabolite
norclozapine (CAS 6104-71-8) in Mexican patients. A prospective study was performed
in 69 in and out psychotic patients taking clozapine. Blood samples were taken at
steady state. Plasma concentrations of clozapine and norclozapine were determined
by HPLC. The results showed that the mean daily dose administered was 250 mg/d. Plasma
levels showed a large interindividual variability. Mean plasma levels were 411.3 ±
328.12 ng/mL, for clozapine and 172.0 ± 129.9 ng/mL for norclozapine. When data were
compared with those reported in other populations, it was found that although the
dose was lower than that reported in Caucasians, the plasma levels were similar. As
a result, the predictive models for the estimation of clozapine concentration in Caucasians
were not appropriate for application in Mexican patients. The findings suggest ethnic
differences in the ratio dose/plasma levels of clozapine in Mexican patients. Further
studies are required to expand the observations.
Key words
Clozapine - Mexican patients - Norclozapine - Plasma levels - Schizophrenia