STRIATAL DOPAMINE-2 RECEPTOR OCCUPANCY IN PSYCHOTIC-PATIENTS TREATED WITH RISPERIDONE

Seventeen psychiatric patients (11 with schizophrenia, 5 with other ps ychotic disorders, and 1 with obsessive-compulsive disorder) were exam ined by single photon emission computed tomography with I-123-iodobenz amide (IBZM) as tracer. Patients were treated with risperidone in two different dosage groups (3 mg and 8 mg) and haloperidol (10-20 mg) and compared with eight healthy control subjects. There was a statistical ly significant difference in basal ganglia/frontal cortex ratios of IB ZM binding between controls and all treatment groups. A statistically significant difference was also found concerning these ratios and perc entage of dopamine D-2 receptor occupancy rates between the treatment groups with lowest ratios and highest percentage of D-2 receptor occup ancy in the group of patients treated with haloperidol, followed by th e group treated with 8 mg of risperidone and the group treated with 3 mg of risperidone. Copyright (C) 1996 Elsevier Science Ireland Ltd.