title: Estimated dopamine D₂ receptor occupancy and remission in schizophrenia: analysis of the CATIE data.
abstract: In treating schizophrenia, 65% to 80% occupancy of dopamine D₂ receptors optimizes therapeutic efficacy while minimizing risks of extrapyramidal symptoms and cognitive impairments. However, it is unclear as to whether it is necessary to keep D₂ receptor occupancy within this therapeutic window to maintain clinical response. The data set from phase 1 of the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) trial was reappraised. Thirty patients receiving risperidone (12 patients), olanzapine (12 patients), or ziprasidone (6 patients) fulfilled the following definition of remission and were included: a score of 3 or less on the 8 specific items in the Positive and Negative Syndrome Scale (ie, P1, P2, P3, N1, N4, N6, G5, and G9; adopted from Andreasen et al, 2005) at the initial assessment and months 1, 2, and 6. Peak and trough D₂ receptor occupancy levels at month 6 were estimated from plasma antipsychotic concentrations using population pharmacokinetic analysis and our D₂ prediction model. Estimated mean ± SD peak and trough D₂ receptor occupancy levels at month 6 were 70.3% ± 9.8% and 60.5% ± 20.2%, respectively; among these individuals, 46.7% (14 patients) did not achieve continuous blockade of 65% or greater (ie, trough D₂ occupancy of <65%). In conclusion, approximately half of patients with remission did not achieve continuous blockade of estimated D₂ receptor occupancy 5% or greater. These results extend our previous findings and suggest that sustained D₂ receptor occupancy greater than 65% may not always be necessary for the maintenance treatment of schizophrenia.
authors.affiliation: Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Moriguchi
authors.forename: Robert R
authors.initials: RR
authors.lastname: Bies
authors.forename: Gary
authors.initials: G
authors.lastname: Remington
authors.forename: Takefumi
authors.initials: T
authors.lastname: Suzuki
authors.forename: David C
authors.initials: DC
authors.lastname: Mamo
authors.forename: Koichiro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Masaru
authors.initials: M
authors.lastname: Mimura
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Pollock
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D018492:Dopamine Antagonists / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D065127:Dopamine D2 Receptor Antagonists; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D000077152:Olanzapine; D010879:Piperazines / Q000627:therapeutic use; D011485:Protein Binding; D011569:Psychiatric Status Rating Scales; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D012074:Remission Induction; D018967:Risperidone / Q000627:therapeutic use; D012559:Schizophrenia / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D012565:Schizophrenic Psychology; D013844:Thiazoles / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
chemical_list: D014150:Antipsychotic Agents; C581293:DRD2 protein, human; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D010879:Piperazines; D017448:Receptors, Dopamine D2; D013844:Thiazoles; D001569:Benzodiazepines; C092292:ziprasidone; D018967:Risperidone; D000077152:Olanzapine