Dose relationship of limbic-cortical D2-dopamine receptor occupancy with risperidone.
BACKGROUND
It has been suggested that the antipsychotic effect of antipsychotics is mediated by the antagonism of the dopamine D2 receptor in the limbic-cortical regions. Risperidone has an atypical property, but its effect on limbic-cortical regions has not been evaluated.


OBJECTIVE
In this study, we examined the relationship among doses of risperidone and limbic-cortical dopamine D2 receptor occupancy using positron emission tomography.


METHODS
Seven patients with schizophrenia were scanned during the steady state with risperidone. Their occupancies in limbic-cortical regions were determined using positron emission tomography with [11C]FLB 457.


RESULTS
The average occupancy ranged from 38% to 80% on doses of 1-6 mg/day. The saturation curve plotted against the drug level fit the data well.


CONCLUSIONS
Our results demonstrate that the D2 receptor occupancy with risperidone in the limbic-cortical regions seems to be similar to that of previous reports regarding the striatum, and it would be comparable to that of typical antipsychotics.
Yasuno
F
F
National Institute of Radiological Sciences, Chiba-shi, Japan. suhara@nirs.go.jp
Suhara
T
T
Okubo
Y
Y
Sudo
Y
Y
Inoue
M
M
Ichimiya
T
T
Tanada
S
S
D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008032:Limbic System / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D018967:Risperidone / Q000097:blood / Q000494:pharmacology*; D012559:Schizophrenia / Q000378:metabolism; D014055:Tomography, Emission-Computed
D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D018967:Risperidone