What is the dosage and usage of Metoprolol (beta-blocker) for hypertension, angina, heart failure, or acute myocardial infarction?

Metoprolol Dosage and Usage Guidelines

For hypertension, angina, heart failure, and acute myocardial infarction, metoprolol should be dosed according to specific protocols with oral metoprolol tartrate 50-200 mg twice daily for angina/hypertension, metoprolol succinate 12.5-200 mg once daily for heart failure, and IV metoprolol 15 mg followed by oral therapy for acute MI. 1, 2

Dosing by Indication

Hypertension and Angina

• Initial dose: 50 mg twice daily of metoprolol tartrate
• Maintenance dose: 100-200 mg twice daily
• Alternative: Metoprolol succinate (extended-release) 50-200 mg once daily
• Target: Heart rate 50-60 beats per minute unless limiting side effects occur 1

Heart Failure

• Starting dose: Metoprolol succinate 12.5-25 mg once daily
• Target dose: 200 mg once daily
• Titration: Gradual increases at 2-week intervals
• Approach: "Start low, go slow" especially in heart failure patients 2

Acute Myocardial Infarction

• Initial IV dosing:
  • Three bolus injections of 5 mg metoprolol tartrate IV
  • Given at approximately 2-minute intervals
  • Requires continuous monitoring of blood pressure, heart rate, and ECG 3
• Subsequent oral therapy:
  • If patient tolerates full IV dose (15 mg): Start 50 mg orally every 6 hours, 15 minutes after last IV dose
  • Continue for 48 hours, then 100 mg orally twice daily maintenance
  • If patient doesn't tolerate full IV dose: Start 25-50 mg orally every 6 hours (based on degree of intolerance) 1, 3

Contraindications and Precautions

Absolute Contraindications

• Marked first-degree AV block (PR interval >0.24 seconds)
• Second or third-degree AV block without functioning pacemaker
• History of asthma
• Cardiogenic shock
• Severe bradycardia (heart rate <50 beats/min)
• Hypotension (systolic BP <90 mmHg) 1, 2

Relative Contraindications/Special Populations

• COPD/Reactive Airway Disease:
  • Use cardioselective agents like metoprolol cautiously
  • Start with low dose (e.g., 12.5 mg metoprolol)
  • Monitor for bronchospasm 1
• Hepatic Impairment:
  • Start with low doses
  • Titrate gradually based on clinical response 3
• Elderly Patients:
  • Lower initial doses due to potential decreased hepatic, renal, or cardiac function 3

Monitoring Parameters

• Heart rate (target 50-60 beats/minute)
• Blood pressure
• ECG (especially during IV administration)
• Signs of heart failure or fluid overload
• Symptoms of bronchospasm
• Daily weight (for heart failure patients) 1, 2

Clinical Pearls

• Beta-blockers without intrinsic sympathomimetic activity (like metoprolol) are preferred for most cardiovascular indications 1
• For heart failure, metoprolol succinate (extended-release) is preferred over metoprolol tartrate due to more consistent plasma levels 2
• In patients at high risk for cardiogenic shock (tachycardia, Killip Class II or III), early aggressive beta blockade should be avoided 1
• For post-MI patients, beta blockers are strongly recommended before discharge even in those with compensated heart failure or LV dysfunction 1
• When initiating therapy in patients with borderline contraindications, consider using a shorter-acting beta-1 selective agent like esmolol initially 1

Metoprolol's beta-1 selectivity makes it preferable in patients with conditions where non-selective beta blockers might be problematic (e.g., diabetes, peripheral vascular disease), though this selectivity is lost at higher doses 1, 2.