title: The influence of CYP2D6 phenotype on the clinical response of nebivolol in patients with essential hypertension.
abstract: BACKGROUND
  * The variability in drug metabolism has been recognized as an important factor in the occurrence of adverse effects or lack of therapeutic efficacy. * The metabolism of the third-generation beta(1)-receptor antagonist nebivolol has been shown to be highly dependent on cytochrome P450 2D6 enzymatic activity in preclinical studies.
  
  
  CONCLUSIONS
  * This paper assesses the role of a cytochrome P450 2D6 gene defect on the antihypertensive response to nebivolol in a clinical setting. * Despite significant differences in drug disposition, the chronic administration of nebivolol produced similar efficacy and tolerability in hypertensive patients either characterized as poor or extensive metabolizers of the drug. * The study offers insight into the relative contribution of nebivolol enantiomers in systemic blood pressure control.
  
  
  OBJECTIVE
  Nebivolol is a beta(1)-adrenergic receptor antagonist with vasodilating properties used in the treatment of hypertension. It is administered as a racemic mixture (D- and L-nebivolol) and is highly metabolized by the cytochrome P-450 2D6 (CYP2D6). The purpose of this study was to determine the role of CYP2D6 phenotypes on the efficacy and tolerability of nebivolol during chronic administration to patients with essential hypertension.
  
  
  METHODS
  Two hundred and eighteen patients were genotyped and phenotyped for CYP2D6 activity, allowing to find and match 14 poor metabolizers (PMs) with 23 extensive metabolizers (EMs). Patients took rac-nebivolol 5 mg daily for 12 weeks. Blood pressure (BP), heart rate, adverse events, plasma levels of the two enantiomers D- and L-nebivolol and their corresponding hydroxymetabolites were assessed.
  
  
  RESULTS
  The metabolic disposition of nebivolol was enantioselective and highly influenced by CYP2D6 phenotypes. Mean steady-state plasma concentrations of D- and L-nebivolol were 10- and 15-fold greater in PMs than in EMs, respectively (P < 0.0001). Despite these differences in the pharmacokinetics of nebivolol, EMs and PMs displayed similar BP responses. Mean reductions in sitting systolic and diastolic BPs were -11/-10 +/- 9/4 mmHg in EMs and -11/-9 +/- 10/5 mmHg in PMs. Side-effects were mild to moderate and not different between groups.
  
  
  CONCLUSIONS
  Polymorphisms in the gene encoding CYP2D6 significantly influenced the metabolism of nebivolol, but not its antihypertensive efficacy and tolerability. The similar clinical response between EMs and PMs could be explained by the contribution of active hydroxylated metabolites of nebivolol to its antihypertensive actions in EMs.
authors.affiliation: Hypertension Research Unit, CHUL Research Center, Faculty of Pharmacy, Laval University, Québec, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Lefebvre
authors.forename: Luc
authors.initials: L
authors.lastname: Poirier
authors.forename: Paul
authors.initials: P
authors.lastname: Poirier
authors.forename: Jacques
authors.initials: J
authors.lastname: Turgeon
authors.forename: Yves
authors.initials: Y
authors.lastname: Lacourciere
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D001578:Benzopyrans / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D004983:Ethanolamines / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D005838:Genotype; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D000068577:Nebivolol; D010641:Phenotype; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D016037:Single-Blind Method; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use
chemical_list: D000959:Antihypertensive Agents; D001578:Benzopyrans; D004983:Ethanolamines; D014665:Vasodilator Agents; D000068577:Nebivolol; D019389:Cytochrome P-450 CYP2D6