SERTINDOLE AND DOPAMINE D-2 RECEPTOR OCCUPANCY IN COMPARISON TO RISPERIDONE, CLOZAPINE AND HALOPERIDOL - A I-123 IBZM SPECT STUDY

The striatal D-2 dopamine binding was studied in schizophrenic patient s treated with the novel atypical antipsychotic drug sertindole (n = 1 0). Comparisons were obtained with haloperidol (n = 8), clozapine (n = 6), risperidone (n = 11) and untreated healthy controls (n 8) of a da taset which has partly been reported previously. I-123-Iodobenzamide ( IBZM) single photon emission computerized tomography (SPECT) was used for estimation of striatal dopamine D-2 receptor binding. Sertindole-t reated patients exhibited significantly (P < 0.001) lower levels of st riatal D-2 binding (BG/FC ratio:1.28) compared with those treated with haloperidol (BG/FC ratio:1.09) and risperidone (8 mg:1.18) but signif icantly (P < 0.005) higher levels compared with clozapine (BG/FC ratio :1.49). However, if patients were pretreated with a depot neuroleptic, significantly (P < 0.05) higher striatal D-2 binding (BG/FC ratio: 1. 12) has been obtained. Since sertindole has been shown to exert distin ct clinical efficacy for treatment of positive and negative symptoms, our data are indicative that antipsychotic efficacy is not associated with a high degree of striatal D-2 receptor occupancy in schizophrenic patients.