title: Melperone is an inhibitor of the CYP2D6 catalyzed O-demethylation of venlafaxine.
abstract: BACKGROUND
  Melperone, a butyrophenone neuroleptic, is frequently used for its sleep-inducing properties. Despite its common use for more than 30 years, it is not yet characterized regarding its effects on cytochrome P450 s (CYPs). In an open pilot study, effects of melperone on the steady-state blood levels of venlafaxine, a recently introduced serotonin- and noradrenaline reuptake inhibiting antidepressant, were assessed.
  
  
  METHODS
  The dose-corrected serum concentrations of venlafaxine and O-desmethylvenlafaxine were analyzed retrospectively in a therapeutic drug-monitoring (TDM) database comprising 94 patients. In addition, three patients received venlafaxine and melperone concomitantly and the serum concentrations of venlafaxine and O-desmethylvenlafaxine were analyzed before, during, and after melperone co-medication. The effect of melperone on CYP2D6 was further assessed in seven patients by means of the dextromethorphan O-demethylation, which serves as a CYP2D6 probe reaction.
  
  
  RESULTS
  Patients treated concomitantly with venlafaxine and melperone had significantly higher (mean +/- SD) venlafaxine (3.27 +/- 2.9 vs. 0.97 +/- 0.99 ng/ml per mg/d; p < 0.05) and lower O-desmethylvenlafaxine serum concentrations (0.69 +/- 0.35 vs. 1.51 +/- 0.9 ng/ml per mg/d; p < 0.01) compared to patients without melperone comedication. In the three patients, venlafaxine serum concentrations increased, on average by 52 % during melperone co-medication, whereas O-desmethylvenlafaxine was decreased, on average by 29 %. Administration of melperone over three days elevated the ratio of dextromethorphan to dextrorphan from 0.044 +/- 0.04 to 0.09 +/- 0.083 (p < 0.05).
  
  
  CONCLUSIONS
  This study pointed to an inhibitory effect of melperone on the O-demethylation of venlafaxine. Because the O-demethylation of venlafaxine is almost exclusively catalyzed by CYP2D6 it is concluded that melperone is an inhibitor of CYP2D6. The hypothesis was further corroborated by the inhibitory effect of melperone on the dextromethorphan O-demethylation.
authors.affiliation: Department of Psychiatry, University of Mainz, Mainz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Grözinger
authors.forename: A
authors.initials: A
authors.lastname: Dragicevic
authors.forename: C
authors.initials: C
authors.lastname: Hiemke
authors.forename: M
authors.initials: M
authors.lastname: Shams
authors.forename: M J
authors.initials: MJ
authors.lastname: Müller
authors.forename: S
authors.initials: S
authors.lastname: Härtter
mesh_terms: D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000008:administration & dosage*; D002090:Butyrophenones / Q000008:administration & dosage*; D003511:Cyclohexanols / Q000097:blood / Q000493:pharmacokinetics*; D019389:Cytochrome P-450 CYP2D6 / Q000378:metabolism; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D004347:Drug Interactions; D016903:Drug Monitoring; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008745:Methylation; D008875:Middle Aged; D012189:Retrospective Studies; D017367:Selective Serotonin Reuptake Inhibitors / Q000097:blood / Q000493:pharmacokinetics*; D012893:Sleep Wake Disorders / Q000188:drug therapy; D000069470:Venlafaxine Hydrochloride
chemical_list: D014150:Antipsychotic Agents; D002090:Butyrophenones; D003511:Cyclohexanols; D019389:Cytochrome P-450 CYP2D6; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D017367:Selective Serotonin Reuptake Inhibitors; D000069470:Venlafaxine Hydrochloride; C008522:metylperon