title: Cytochrome P450 2D6 phenotype predicts antidepressant efficacy of venlafaxine: a secondary analysis of 4 studies in major depressive disorder.
abstract: BACKGROUND
  Venlafaxine, a serotonin-norepinephrine reuptake inhibitor antidepressant, is metabolized primarily by the cytochrome P450 2D6 enzyme into O-desmethylvenlafaxine (ODV). The ODV/venlafaxine ratio can be used to distinguish between extensive metabolizers (EMs) and poor metabolizers (PMs).
  
  
  OBJECTIVE
  To determine the relative efficacy and tolerability of venlafaxine in EM vs PM patients with major depressive disorder (MDD).
  
  
  METHODS
  Data from 4 double-blind, placebo-controlled studies of patients with MDD were pooled. Blood samples were analyzed for plasma concentrations of venlafaxine, ODV, total venlafaxine + ODV, and ODV/venlafaxine ratio. Patients were classified as EMs or PMs on the basis of ODV/venlafaxine ratios. Changes from baseline in depression scale scores were compared between EMs and PMs using t tests. Rates of response, remission, discontinuation, and adverse events (AEs) were compared for EMs and PMs using Fisher exact tests.
  
  
  RESULTS
  Compared with PMs, EMs had significantly greater mean changes from baseline on 4 of 5 depression rating scales (all 4 comparisons, P ≤ .020). A significantly greater percentage of EMs achieved response or remission by most measures compared with PMs (4 of 5 comparisons, P ≤ .015). Rates of discontinuation and AEs did not differ significantly between EMs and PMs. Since there were no substantial differences between EMs and PMs in terms of venlafaxine dose or tolerability, these factors are not likely to account for the efficacy findings.
  
  
  CONCLUSIONS
  Venlafaxine treatment in EMs was associated with greater efficacy in MDD on virtually all measures compared with PMs, with no important tolerability differences.
authors.affiliation: Wyeth Research, Collegeville, Pennsylvania 19426, USA. kasia.lobello@pfizer.com
authors.forename: Kasia W
authors.initials: KW
authors.lastname: Lobello
authors.forename: Sheldon H
authors.initials: SH
authors.lastname: Preskorn
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Guico-Pabia
authors.forename: Qin
authors.initials: Q
authors.lastname: Jiang
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Paul
authors.forename: Alice I
authors.initials: AI
authors.lastname: Nichols
authors.forename: Albena
authors.initials: A
authors.lastname: Patroneva
authors.forename: Philip T
authors.initials: PT
authors.lastname: Ninan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000188:drug therapy* / Q000235:genetics; D003511:Cyclohexanols / Q000009:adverse effects / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use*; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D000069468:Desvenlafaxine Succinate; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011569:Psychiatric Status Rating Scales; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use*; D016896:Treatment Outcome; D000069470:Venlafaxine Hydrochloride; D055815:Young Adult
chemical_list: D003511:Cyclohexanols; D019389:Cytochrome P-450 CYP2D6; D000069468:Desvenlafaxine Succinate; D017367:Selective Serotonin Reuptake Inhibitors; D000069470:Venlafaxine Hydrochloride