Pharmacodynamic Study of Carvedilol Versus Metoprolol in Heart Failure

Metoprolol succinate is a beta1-selective beta-blocker, becoming non-selective at higher doses, while carvedilol is non-selective. We examined whether metoprolol remained beta1-selective compared to carvedilol during dose up-titration in Class C heart failure (HF) Beta-blocker naïve patients. METHODS: Twenty-five NYHA FC II-III HF patients were randomized to carvedilol or metoprolol. Patients were studied at baseline and after 2 weeks of up-titration (metoprolol at 25, 50, 100, and 200 mg daily; carvedilol IR at 3.125, 6.25, 12.5, 25 mg and 50mg twice daily). Beta2- blockade was determined by an infusion of terbutaline at 6 mg/kg over 1 hour. Glucose and potassium levels were serially measured at baseline, every 15 minutes for the 1st hour and 30 minutes for 2nd hour post-infusion. The median area under the curve (AUC) for glucose and potassium changes were calculated.