What are the differences between Coreg (carvedilol) and metoprolol?

Differences Between Carvedilol (Coreg) and Metoprolol

Carvedilol is preferred over metoprolol for heart failure patients due to its additional alpha-blocking properties and superior mortality reduction, while metoprolol is more cardioselective and may be better for patients with reactive airway disease.

Pharmacological Properties

Receptor Selectivity

• Carvedilol: Nonselective beta-blocker with additional alpha-1 blocking activity 1
• Metoprolol: Beta-1 selective (cardioselective) adrenergic receptor blocker 2

Mechanism of Action

• Carvedilol:

  • Blocks beta-1, beta-2, and alpha-1 receptors
  • Has antioxidant properties
  • Reduces plasma renin activity
  • Increases atrial natriuretic peptide levels 1

• Metoprolol:

  • Primarily blocks beta-1 receptors in the heart
  • At higher doses, may also affect beta-2 receptors in bronchial and vascular musculature
  • Reduces heart rate, cardiac output, and blood pressure 2

Clinical Efficacy

Heart Failure

• Carvedilol:

  • Demonstrated 17% greater mortality reduction compared to metoprolol tartrate in the COMET trial 3
  • Preferred in patients with heart failure with reduced ejection fraction (HFrEF) 4
  • Shows greater improvement in left ventricular ejection fraction compared to metoprolol 5

• Metoprolol:

  • Effective for heart failure, but metoprolol succinate (extended-release) should be used rather than metoprolol tartrate 4
  • The MERIT-HF trial showed 34% reduction in mortality with metoprolol succinate 4

Hypertension

• Carvedilol:

  • More effective at lowering blood pressure due to additional alpha-blocking effects 6
  • May be preferred in patients with concomitant hypertension and heart failure 4

• Metoprolol:

  • More cardioselective, making it potentially safer in patients with respiratory conditions 4
  • Less effect on blood pressure compared to carvedilol 6

Dosing Considerations

Starting and Target Doses

• Carvedilol:

  • Starting dose: 3.125 mg twice daily
  • Target dose: 25-50 mg twice daily (depending on patient weight) 4, 7

• Metoprolol:

  • Starting dose: 12.5-25 mg once daily (succinate form)
  • Target dose: 200 mg once daily (succinate form) 4, 7

Titration

• Both medications require gradual titration over several weeks to reach target doses
• Dose may be doubled every 1-2 weeks if the preceding dose was well tolerated 4

Side Effects and Tolerability

Common Side Effects

• Carvedilol:

  • More pronounced hypotension due to alpha-blocking effects
  • May have more favorable effects on glycemic control 4
  • Similar rates of bradycardia compared to metoprolol 3

• Metoprolol:

  • Less hypotension than carvedilol
  • May have less favorable metabolic profile 4

Special Populations

Respiratory Disease

• Metoprolol: Preferred in patients with asthma or COPD due to beta-1 selectivity 4
• Carvedilol: Greater risk of bronchospasm due to beta-2 blockade 4

Diabetes

• Carvedilol: May have more favorable effects on glycemic control 4
• Metoprolol: Less favorable metabolic profile

Practical Considerations

Formulations

• Carvedilol: Available as immediate-release and phosphate extended-release formulations 4
• Metoprolol: Available as tartrate (immediate-release) and succinate (extended-release) formulations - the succinate form is preferred for heart failure 4

Contraindications (similar for both)

• Severe bradycardia
• Heart block (second or third degree) without pacemaker
• Cardiogenic shock
• Decompensated heart failure requiring IV inotropic therapy 4

Clinical Decision Making

1. For heart failure patients:

   • Choose carvedilol if the patient has no respiratory issues and can tolerate potential hypotension 4
   • Consider metoprolol succinate if the patient has reactive airway disease 4

2. For hypertension patients:

   • Choose carvedilol if additional blood pressure lowering is needed 6
   • Choose metoprolol if the patient has respiratory concerns 4

3. For post-MI patients:

   • Both are effective, but metoprolol may be preferred if cardioselectivity is important 4

Important Caveats

• Never abruptly discontinue either medication due to risk of rebound hypertension and tachycardia 7
• Metoprolol tartrate is not equivalent to metoprolol succinate - the succinate form should be used for heart failure 4
• The COMET trial showed superiority of carvedilol over metoprolol tartrate, but some studies comparing carvedilol to metoprolol succinate show similar outcomes 8, 9