In vivo (123)I IBZM SPECT imaging of striatal dopamine 2 receptor occupancy in schizophrenic patients.
BACKGROUND
Single photon emission computed tomography (SPECT) using (123)I iodobenzamide (IBZM) as tracer substance has been shown to be a useful tool to visualize dopamine 2 (D2) receptor occupancy.


OBJECTIVE
We investigated the striatal D2 receptor occupancy of zotepine which is referred to the class of atypical antipsychotic drugs.


METHODS
(123)I IBZM and SPECT were used to visualize striatal dopamine 2 (D2) receptor occupancy in zotepine-treated 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 binding in patients treated with antipsychotics was compared to untreated healthy controls (n=8) reported earlier.


RESULTS
Zotepine led to a mean overall striatal D2 receptor occupancy of 73%. Patients with 150 mg daily showed 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 clinical improvement.
Barnas
C
C
Department of General Psychiatry, University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.
Quiner
S
S
Tauscher
J
J
Hilger
E
E
Willeit
M
M
Küfferle
B
B
Asenbaum
S
S
Brücke
T
T
Rao
M L
ML
Kasper
S
S
D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics; D003988:Dibenzothiepins / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007462:Iodobenzenes; D008297:Male; D017072:Neostriatum / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D012559:Schizophrenia / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon
D014150:Antipsychotic Agents; D003988:Dibenzothiepins; D007462:Iodobenzenes; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; C426805:idobenzamide; C022172:zotepine