Sertindole and dopamine D2 receptor occupancy in comparison to risperidone, clozapine and haloperidol – a 123I-IBZM SPECT study

Abstract

The striatal D₂ dopamine binding was studied in schizophrenic patients treated with the novel atypical antipsychotic drug sertindole (n = 10). Comparisons were obtained with haloperidol (n = 8), clozapine (n = 6), risperidone (n = 11) and untreated healthy controls (n = 8) of a dataset which has partly been reported previously. ¹²³I-Iodobenzamide (IBZM) single photon emission computerized tomography (SPECT) was used for estimation of striatal dopamine D₂ receptor binding. Sertindole-treated patients exhibited significantly (P < 0.001) lower levels of striatal D₂ binding (BG/FC ratio:1.28) compared with those treated with haloperidol (BG/FC ratio:1.09) and risperidone (8 mg:1.18) but significantly (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 D₂ binding (BG/FC ratio:1.12) has been obtained. Since sertindole has been shown to exert distinct 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 D₂ receptor occupancy in schizophrenic patients.