title: Extended-release metoprolol succinate in chronic heart failure.
abstract: OBJECTIVE
  To review the pharmacology, pharmacokinetics, efficacy, and tolerability of extended-release (ER) metoprolol succinate and its role in the management of chronic heart failure.
  
  
  METHODS
  A MEDLINE search of English-language literature (1990-October 2002) was conducted using congestive heart failure and metoprolol CR/XL or metoprolol CR/ZOK as search terms to identify pertinent studies.
  
  
  METHODS
  All of the articles identified from the data sources were evaluated, with priority given to randomized, double-blind, placebo-controlled studies.
  
  
  RESULTS
  ER metoprolol succinate is a controlled-release tablet designed to produce even and consistent beta(1)-blockade throughout the 24-hour dosing interval, with less fluctuation in metoprolol plasma concentrations compared with immediate-release metoprolol. Three randomized, double-blind, placebo-controlled trials have evaluated the efficacy of ER metoprolol succinate in the treatment of patients with chronic heart failure. The MERIT-HF (Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure) study, the largest of these trials and the largest randomized mortality trial with beta-blockers in heart failure to date, demonstrated that ER metoprolol succinate reduced the relative risk of all-cause mortality by 34% versus placebo. Furthermore, the relative risk of the combined endpoint of mortality plus all-cause hospitalizations was reduced by 19% and sudden death was reduced by 41%. The benefits of therapy were evident in various patient subgroups, including elderly patients and those with diabetes mellitus. ER metoprolol succinate was generally well tolerated, with a similar proportion of patients discontinuing therapy due to adverse events relative to placebo (9.8% and 11.7%, respectively).
  
  
  CONCLUSIONS
  ER metoprolol succinate therapy provides substantial mortality and morbidity benefits in patients with New York Heart Association class II and III heart failure who are stabilized on angiotensin-converting enzyme inhibitors and diuretics. ER metoprolol succinate is administered once daily, is well tolerated, and provides consistent beta(1)-blockade over the 24-hour dosing interval.
authors.affiliation: School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599-7360, USA.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Tangeman
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Patterson
mesh_terms: D003692:Delayed-Action Preparations / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D004347:Drug Interactions; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D008790:Metoprolol / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic
chemical_list: D003692:Delayed-Action Preparations; D008790:Metoprolol