What is the recommended dosage and administration of Metoprolol (metoprolol tartarate) for patients with hypertension, angina, or heart failure?

Metoprolol Tartrate: Dosing and Administration

Metoprolol tartrate should NOT be used as the preferred beta-blocker for heart failure, as it lacks mortality benefit compared to metoprolol succinate (extended-release), which demonstrated a 34% reduction in all-cause mortality in the MERIT-HF trial. 1

Critical Distinction Between Formulations

Metoprolol succinate (extended-release) is the ONLY metoprolol formulation proven to reduce mortality in heart failure. 2 The European Society of Cardiology explicitly states that metoprolol tartrate should not be used in preference to evidence-based beta-blockers in heart failure patients. 1 This distinction is crucial because the COMET trial demonstrated superior survival with carvedilol compared to immediate-release metoprolol tartrate. 3

Dosing by Indication

Hypertension

• Initial dose: 25-50 mg twice daily 4, 2
• Maintenance range: 50-200 mg twice daily 2
• Maximum dose: 200 mg daily 4, 2
• Titration: Increase gradually every 1-2 weeks if blood pressure control is inadequate 4

Important caveat: Beta-blockers are not first-line agents for hypertension unless the patient has coexisting ischemic heart disease or heart failure. 2

Angina Pectoris

• Usual dose: 50-200 mg twice daily 2
• Target: Resting heart rate of 50-60 beats per minute 4, 2
• Titration: Adjust based on heart rate response and symptom control 2

Acute Myocardial Infarction (Early Treatment)

IV Administration (in coronary care unit): 5

• Dose: 5 mg IV bolus over 1-2 minutes 5
• Repeat: Every 5 minutes for total of 15 mg maximum 5
• Monitoring: Continuous blood pressure, heart rate, and ECG during IV administration 5

Transition to Oral (after IV dosing): 5

• Timing: 15 minutes after last IV dose 5
• Initial oral dose: 50 mg every 6 hours for 48 hours (if full IV dose tolerated) 5
• Maintenance: 100 mg twice daily after 48 hours 2, 5

Critical contraindications for IV metoprolol in acute MI: 2

• Signs of heart failure or low output state
• Systolic BP <120 mmHg
• Heart rate >110 bpm or <60 bpm
• PR interval >0.24 seconds
• Second or third-degree heart block
• Active asthma or reactive airways disease
• Age >70 years (increased cardiogenic shock risk)

The COMMIT trial demonstrated that early IV metoprolol increased cardiogenic shock risk by 30%, particularly in high-risk patients. 4 Therefore, avoid aggressive early IV beta-blockade in hemodynamically unstable patients. 2

Heart Failure: Use Metoprolol Succinate Instead

For heart failure with reduced ejection fraction, ONLY metoprolol succinate (extended-release) should be used, NOT metoprolol tartrate. 1, 2

If metoprolol succinate is used: 2

• Starting dose: 12.5-25 mg once daily
• Target dose: 200 mg once daily
• Titration: Every 2 weeks

The evidence is unequivocal that metoprolol tartrate lacks the mortality benefit demonstrated with metoprolol succinate in the MERIT-HF trial. 6

Monitoring and Dose Adjustments

Symptomatic Bradycardia (HR <50 bpm with symptoms)

• Action: Halve the beta-blocker dose 1
• If severe deterioration: Stop beta-blocker (rarely necessary) 1
• Review: Other heart rate-slowing drugs (digoxin, amiodarone, diltiazem, verapamil) 1
• Obtain: ECG to exclude heart block 1

Symptomatic Hypotension

• First: Reconsider nitrates, calcium-channel blockers, and other vasodilators 1
• Second: If no congestion, consider reducing diuretic dose 1
• If unresolved: Seek specialist advice 1

Worsening Heart Failure Symptoms

• If increasing congestion: Increase diuretic dose or halve beta-blocker dose 1
• If marked fatigue: Halve beta-blocker dose 1
• Review in 1-2 weeks: If not improved, seek specialist advice 1

Critical Warnings

Never abruptly discontinue metoprolol. 1, 2 Sudden cessation carries risk of rebound myocardial ischemia, infarction, and arrhythmias. 1 The ACC/AHA guidelines document a 2.7-fold increased risk of 1-year mortality with beta-blocker withdrawal compared to continuous use. 4 Ideally, seek specialist advice before discontinuation. 1

Special Populations

Hepatic Impairment

Metoprolol tartrate blood levels increase substantially in hepatic impairment. 5 Initiate at low doses with cautious gradual titration. 5

Renal Impairment

No dose adjustment required. 5

Geriatric Patients (>65 years)

Use low initial starting dose given greater frequency of decreased hepatic, renal, or cardiac function. 5

Common Pitfalls to Avoid

• Do not use metoprolol tartrate for heart failure when metoprolol succinate is the evidence-based formulation 1, 2
• Do not give IV metoprolol to hemodynamically unstable patients in acute MI 2
• Do not stop metoprolol abruptly without specialist consultation 1
• Do not assume medium-range doses provide equivalent benefit to target doses - higher doses have demonstrated greater benefits in clinical trials 1