In vivo occupancy of striatal and temporal cortical D2/D3 dopamine receptors by typical antipsychotic drugs. [123I]epidepride single photon emission tomography (SPET) study.

Abstract

BACKGROUND:

The dopamine hypothesis proposes that antipsychotic drugs act primarily through limbic cortical D2/D2-like dopamine receptor blockade.

AIM:

To evaluate this hypothesis with the D2/D3-selective SPET probe [123I]-epidepride.

METHOD:

[123I]-epidepride SPET scans were performed on 12 patients with schizophrenia treated with antipsychotics and II age-matched healthy controls. [123I]-epidepride 'specific binding' to D2/D3 dopamine receptors was estimated, and relative percentage D2/D3 receptor occupancy by typical antipsychotic drugs determined.

RESULTS:

Mean (s.d.) daily dose was 669.12 (516.8) mg chlorpromazine equivalents. Mean percentage D2/D3 receptor occupancy was 81.6 (8.1) and 73.2 (13.9) in the temporal cortex and striatum respectively.

CONCLUSIONS:

Typical antipsychotic drug treatment is associated with substantial temporal cortical D2/D3 receptor occupancy. The relationship between this and efficacy is poor in patients with treatment-resistant schizophrenia.

• Authors: V Bigliani, R S Mulligan, P D Acton, D Visvikis, P J Ell, C Stephenson, R W Kerwin, L S Pilowsky
• Journal: The British journal of psychiatry : the journal of mental science (Br J Psychiatry) Vol. 175 Pg. 231-8 (Sep 1999) ISSN: 0007-1250 [Print] England
• PMID: 10645324 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antipsychotic Agents
• Benzamides
• Iodine Radioisotopes
• Pyrrolidines
• Receptors, Dopamine D1
• Receptors, Dopamine D2
• epidepride

Topics

• Adult
• Antipsychotic Agents (metabolism, therapeutic use)
• Benzamides
• Female
• Humans
• Iodine Radioisotopes
• Male
• Middle Aged
• Pyrrolidines
• Receptors, Dopamine D1 (metabolism)
• Receptors, Dopamine D2 (metabolism)
• Schizophrenia (drug therapy, metabolism)
• Temporal Lobe (metabolism)
• Tomography, Emission-Computed (methods)