Plasma clozapine levels and clinical response for treatment-refractory schizophrenic patients.
OBJECTIVE
The purpose of this study was to determine if plasma clozapine levels were associated with treatment response.


METHODS
To examine this question, neuroleptic nonresponsive patients with schizophrenia or schizoaffective disorder were given clozapine, which was titrated to 500 mg/day by day 14 of treatment, and the dose was held fixed at least through day 21. Subsequently, clozapine doses were adjusted as clinically indicated, up to a maximum of 900 mg/day. Plasma clozapine levels were obtained at weeks 3 and 6, and standard clinical ratings (Brief Psychiatric Rating Scale [BPRS] and Clinical Global Impression) were done at baseline and at weeks 3 and 6.


RESULTS
Data from 45 subjects were analyzed. There were no correlations between plasma clozapine levels and change in BPRS scores at treatment weeks 3 and 6. However, when the subjects were classified as responders or nonresponders, therapeutic response was associated with clozapine blood levels above 350 ng/ml.


CONCLUSIONS
This study suggest that clozapine blood levels are correlated with clinical response.
Hillside Hospital, Long Island Jewish Medical Center, Glen Oaks, NY 11004.
M H
MH
Kronig
R A
RA
Munne
S
S
Szymanski
A Z
AZ
Safferman
S
S
Pollack
T
T
Cooper
J M
JM
Kane
J A
JA
Lieberman
D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D003024:Clozapine / Q000097:blood* / Q000627:therapeutic use; D004351:Drug Resistance; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000097:blood / Q000188:drug therapy; D012372:ROC Curve; D012559:Schizophrenia / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D014150:Antipsychotic Agents; D003024:Clozapine