C. Barnas et al., In vivo I-123 IBZM SPECT imaging of striatal dopamine 2 receptor occupancyin schizophrenic patients, PSYCHOPHAR, 157(3), 2001, pp. 236-242
Rationale: Single photon emission computed tomography (SPECT) using I-123 i
odobenzamide (IBZM) as tracer substance has been shown to be a useful tool
to visualize dopamine 2 (D2) receptor occupancy. Objectives: We investigate
d the striatal D2 receptor occupancy of zotepine which is referred to the c
lass of atypical antipsychotic drugs. Methods: I-123 IBZM and SPECT were us
ed to visualize striatal dopamine 2 (D2) receptor occupancy in zotepine-tre
ated schizophrenic patients. Two groups of schizophrenic patients receiving
either 150 mg/day zotepine (n=6) or 300 mg/day (n=6) underwent examination
. For the quantification of striatal D2 receptor occupancy, striatal IBZM b
inding in patients treated with antipsychotics was compared to untreated he
althy controls (n=8) reported earlier. Results: Zotepine led to a mean over
all striatal D2 receptor occupancy of 73%. Patients with 150 mg daily showe
d a significantly lower occupancy (65.8%, SD=6.2) than patients with 300 mg
/day (77.8%, SD=10.7; P <0.05). No clinically relevant extrapyramidal side
effects occurred during treatment with zotepine. Conclusions: There was no
correlation between the degree of striatal D2 receptor occupancy and clinic
al improvement.