title: Striatal and extra-striatal D(2)/D(3) dopamine receptor occupancy by quetiapine in vivo. [(123)I]-epidepride single photon emission tomography(SPET) study.
abstract: BACKGROUND
  Selective action at limbic cortical dopamine D(2)-like receptors could mediate atypical antipsychotic efficacy with few extrapyramidal side-effects.
  
  
  OBJECTIVE
  To test the hypothesis that quetiapine has 'limbic selective' D(2)/D(3) receptor occupancy in vivo.
  
  
  METHODS
  The high-affinity D(2)/D(3) ligand [(123)I]-epidepride and single photon emission tomography were used to estimate D(2)/D(3) specific binding and an index of relative percentage D(2)/D(3) occupancy in striatal and temporal cortical regions for quetiapine-treated patients (n=6). Quetiapine-, and previously studied typical-antipsychotic- and clozapine-treated patients were compared.
  
  
  RESULTS
  Mean (s.d.) relative percentage D(2)/D(3) receptor occupancy by quetiapine was 32.0% (14.6) in striatum and 60.1% (17.2) in temporal cortex (mean daily dose 450 mg: range 300-700 mg/day). Quetiapine treatment resulted in limbic selective D(2)/D(3) blockade similar to clozapine and significantly higher than typical antipsychotics.
  
  
  CONCLUSIONS
  Preliminary data suggest that limbic selective D(2)/D(3) receptor blockade is important for atypical drug action.
authors.affiliation: Institute of Psychiatry, London.
authors.forename: C M
authors.initials: CM
authors.lastname: Stephenson
authors.forename: V
authors.initials: V
authors.lastname: Bigliani
authors.forename: H M
authors.initials: HM
authors.lastname: Jones
authors.forename: R S
authors.initials: RS
authors.lastname: Mulligan
authors.forename: P D
authors.initials: PD
authors.lastname: Acton
authors.forename: D
authors.initials: D
authors.lastname: Visvikis
authors.forename: P J
authors.initials: PJ
authors.lastname: Ell
authors.forename: R W
authors.initials: RW
authors.lastname: Kerwin
authors.forename: L S
authors.initials: LS
authors.lastname: Pilowsky
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000378:metabolism*; D001549:Benzamides; D003024:Clozapine / Q000378:metabolism; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D003987:Dibenzothiazepines / Q000378:metabolism*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011759:Pyrrolidines; D000069348:Quetiapine Fumarate; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D014150:Antipsychotic Agents; D001549:Benzamides; C493593:DRD3 protein, human; D003987:Dibenzothiazepines; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C063525:epidepride; D000069348:Quetiapine Fumarate; D003024:Clozapine