A Study to Compare the Effects of Coreg CR and Coreg IR on Heart Function in Subjects With Stable Chronic Heart Failure

Results of clinical trials have shown beta-blockers improve symptoms and left ventricular function, reduce hospitalizations and death in heart failure, and prolong survival \[MERIT-HF, CIBIS-II, Packer, 1996\]. Clinical guidelines mandate use of beta-blockers in treatment of subjects with heart failure. Carvedilol (Coreg IR) is a multiple action adrenergic receptor blocker with alpha 1, beta 1 and beta 2 receptor blockade properties. The beta-adrenergic properties are non-selective for beta 1 and beta 2 adrenergic receptors. Coreg IR, administered twice daily, is marketed in the United States for long term treatment of mild-moderate hypertension, mild to severe heart failure and subjects surviving an acute myocardial infarction with left ventricular dysfunction with or without symptomatic heart failure. Coreg IR significantly reduces all cause mortality and the need for cardiovascular hospitalization \[Packer, 1996a; Packer, 1996b; Colucci, 1996; Cohn, 1997; Olsen, 1995; Sharpe 1997\]. The effect of Coreg is dose dependent \[Bristow, 1996\]. In subjects treated long term after an acute myocardial infarction (MI) complicated by left ventricular systolic dysfunction, Coreg IR reduced the frequency of all-cause and cardiovascular mortality, and recurrent non-fatal MIs. These beneficial effects are additional to those of evidence-based treatments for acute MI, including ACE inhibitors \[Dargie, 2001\]. Left Ventricular End Systolic Volume Index (LVESVI) is an important measure of ventricular function and remodeling in the evaluation of heart failure. In controlled clinical trials, Coreg IR, administered twice daily, has reduced LVESVI in subjects with ischemic heart failure. An echocardiography substudy of the Australia-New Zealand Trial \[Doughty, 1997\], evaluated left ventricular remodeling in 123 subjects with ischemic heart failure with an LVEF \< 45 randomized to carvedilol or placebo. The LVESVI was reduced by 6.2 + 1.6 ml/m2 after 6 months and 8.7 + 2.6 ml/m2 after 12 months of carvedilol therapy compared to the placebo treated subjects. Metra et al \[Metra, 2000\] observed the favorable effects of carvedilol compared with metoprolol on LVEF, LV stroke volume, and pulmonary artery pressure despite similar effects on cardiovascular outcome. Both groups also showed significant decreases in LV systolic volume. Doughty et al \[Doughty, 2004\] observed the favorable effects of carvedilol on LV remodeling, with improved LV end-systolic volume and ejection fraction, after 6 months of treatment. Carvedilol phosphate CR (Coreg CR) is an approved, modified release, once-daily formulation of carvedilol that is hoped to provide an advance in patient care through improved compliance with prescribed dose. The clinical experience with various formulations of Coreg CR is limited to eight single dose studies in healthy subjects and one repeated dose study in subjects with hypertension. In total 230, adult subjects have received at least one dose of Coreg IR or one of several CR formulations across nine studies. The subjects ranged in age from 18 to 63 years; 62% were male and 69% were white. The various formulations of Coreg CR capsules were safe and well tolerated in single dose pharmacokinetic studies in doses ranging from 6.25 to 60 mg in healthy subjects. The most common adverse events were headache, dizziness and orthostatic hypotension and are all known adverse events following administration of Coreg IR \[GSK Study 386, 388, 399, 400, 402, 907\]. This study will be the first controlled clinical study investigating the efficacy of treatment with Coreg CR formulation \[Coreg CR filled with 7.5 mg of carvedilol phosphate immediate release (IRp) microparticles, 22.5 mg of carvedilol phosphate Micropump IIa MR microparticles, and 30 mg of carvedilol phosphate Micropump IIc MR microparticles\] compared to Coreg IR evaluating LVESVI in subjects with stable chronic heart failure.