title: 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.
  
  
  OBJECTIVE
  To evaluate this hypothesis with the D2/D3-selective SPET probe [123I]-epidepride.
  
  
  METHODS
  [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.affiliation: Institute of Psychiatry, London.
authors.forename: V
authors.initials: V
authors.lastname: Bigliani
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: C
authors.initials: C
authors.lastname: Stephenson
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* / Q000627:therapeutic use; D001549:Benzamides; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011759:Pyrrolidines; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012559:Schizophrenia / Q000188:drug therapy / Q000378:metabolism*; D013702:Temporal Lobe / Q000378:metabolism*; D014055:Tomography, Emission-Computed / Q000379:methods
chemical_list: D014150:Antipsychotic Agents; D001549:Benzamides; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C063525:epidepride