PLASMA CLOZAPINE LEVELS AND CLINICAL-RESPONSE FOR TREATMENT-REFRACTORY SCHIZOPHRENIC-PATIENTS

Objective: The purpose of this study was to determine if plasma clozap ine levels were associated with treatment response. Method: To examine this question, neuroleptic nonresponsive patients with schizophrenia or schizoaffective disorder were given clozapine, which was titrated t o 500 mg/day by day 14 of treatment, and the dose was held fixed at le ast through day 21. Subsequently, clozapine doses were adjusted as cli nically indicated, up to a maximum of 900 mg/day. Plasma clozapine lev els were obtained at weeks 3 and 6, and standard clinical ratings (Bri ef Psychiatric Rating Scale [BPRS] and Clinical Global Impression) wer e done at baseline and at weeks 3 and 6. Results: Data from 45 subject s were analyzed. There were no correlations between plasma clozapine l evels and change in BPRS scores at treatment weeks 3 and 6. However, w hen the subjects were classified as responders or nonresponders, thera peutic response was associated with clozapine blood levels above 350 n g/ml. Conclusions: This study suggests that clozapine blood levels are correlated with clinical response.