Send to

Choose Destination
See comment in PubMed Commons below
J Clin Psychopharmacol. 1993 Dec;13(6):383-90.

Relationship between clinical efficacy and clozapine concentrations in plasma in schizophrenia: effect of smoking.

Author information

Department of Psychiatry, Case Western Reserve University, School of Medicine, Cleveland, Ohio.


Concentrations in plasma of clozapine and norclozapine, the major metabolite of clozapine, were measured in 59 treatment-resistant schizophrenic patients at a random time period during the course of treatment. A lower sum of the concentrations of clozapine and norclozapine or either alone predicted less improvement in the Brief Psychiatric Rating Scale (BPRS) Total and Positive symptoms in a multivariate analysis that controlled for baseline BPRS rating and dose. The mean doses of clozapine after 6 months of treatment and at the time of blood sampling were not significantly different in 30 responders and 29 nonresponders to clozapine, on the basis of the decrease in BPRS Total scores, whereas the concentrations in plasma in clozapine of norclozapine and the sum of their concentrations were significantly higher in responders. Clozapine and norclozapine concentrations in plasma correlated both with dose at the time of sampling and with dose at 6 months. A clozapine concentration of 370 ng/ml was the optimal cutoff for distinguishing responders from nonresponders. Clozapine and norclozapine concentrations did not differ in male smokers and nonsmokers.

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Support Center