title: Differential effects of carvedilol and metoprolol succinate on plasma norepinephrine release and peak exercise heart rate in subjects with chronic heart failure.
abstract: Dosing equivalency of carvedilol and metoprolol remains a debate. Degree of beta 1-blockade is best assessed by blunting of the exercise-induced heart rate. Accordingly, the authors have investigated dosing equivalency by examining baseline and peak exercise heart rates and norepinephrine levels in subjects with chronic heart failure treated with carvedilol or metoprolol. Thirty-seven subjects treated with carvedilol (32.9 +/- 3.5 mg; n = 23) or metoprolol succinate (XL) (96.4 +/- 15.9 mg; n = 14) referred for cardiopulmonary exercise testing were studied prospectively. Carvedilol versus metoprolol XL subjects did not differ with respect to baseline heart rate (73 +/- 2 vs 70 +/- 3 bpm), or baseline plasma norepinephrine levels (597.5 +/- 78.3 vs 602.1 +/- 69.6 pg/mL), P = NS. However, despite similar peak exercise norepinephrine levels (2735.8 +/- 320.1 vs 2403.1 +/- 371.6 pg/mL), heart rate at peak exercise was higher in subjects receiving carvedilol (135 +/- 4 bpm) than those receiving metoprolol XL (117 +/- 6 bpm), P = 0.02. Similar norepinephrine release and more complete beta 1-blockade is observed in well-matched subjects with chronic heart failure treated with a mean daily dose of metoprolol XL 96.4 mg compared with carvedilol 32.9 mg.
authors.affiliation: Division of Cardiology, Albert Einstein College of Medicine, Bronx, NY 10461, USA. tvittori@ montefiore.org
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Vittorio
authors.forename: Ronald
authors.initials: R
authors.lastname: Zolty
authors.forename: Michael E
authors.initials: ME
authors.lastname: Kasper
authors.forename: Raj M
authors.initials: RM
authors.lastname: Khandwalla
authors.forename: David S
authors.initials: DS
authors.lastname: Hirsh
authors.forename: Chi-Hong
authors.initials: CH
authors.lastname: Tseng
authors.forename: Ulrich P
authors.initials: UP
authors.lastname: Jorde
authors.forename: Kartikya
authors.initials: K
authors.lastname: Ahuja
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D002227:Carbazoles / Q000008:administration & dosage / Q000494:pharmacology*; D000077261:Carvedilol; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000188:drug therapy; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood* / Q000378:metabolism; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology*; D011446:Prospective Studies
chemical_list: D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol; D008790:Metoprolol; D009638:Norepinephrine