What is the maximum dose of metoprolol (beta-blocker) for a patient with hypertension, considering their medical history and potential conditions such as heart failure or asthma?

Maximum Dose of Metoprolol

The maximum dose of metoprolol depends on the formulation and indication: metoprolol tartrate (immediate-release) has a maximum of 200 mg twice daily (400 mg total daily), while metoprolol succinate (extended-release) has a maximum of 400 mg once daily. 1

Formulation-Specific Maximum Doses

Metoprolol Tartrate (Immediate-Release)

• Maximum dose is 200 mg twice daily for hypertension and chronic maintenance therapy 2, 1
• For acute IV administration, the maximum total dose is 15 mg (administered as three 5 mg boluses given 5 minutes apart) 2, 1
• After IV administration, oral therapy can be initiated at 25-50 mg every 6 hours for 48 hours 1

Metoprolol Succinate (Extended-Release)

• Maximum dose is 400 mg once daily 1, 3
• For hypertension, dosing ranges from 50-400 mg once daily 1, 3
• For atrial fibrillation rate control, the range is 50-400 mg once daily 1, 3

Indication-Specific Dosing

Heart Failure with Reduced Ejection Fraction (HFrEF)

• Target dose is 200 mg once daily of metoprolol succinate extended-release 1, 3, 4
• This is the dose proven to reduce mortality by 34% in the MERIT-HF trial 1, 4
• Only metoprolol succinate (not tartrate) has demonstrated mortality reduction in heart failure 1, 3
• If target dose cannot be achieved, aim for at least 50% (100 mg daily minimum) to maintain mortality benefit 1, 3

Hypertension

• Metoprolol tartrate: 100-200 mg daily in divided doses (maximum 200 mg twice daily) 3
• Metoprolol succinate: 50-400 mg once daily 1, 3

Atrial Fibrillation Rate Control

• Metoprolol tartrate: 25-100 mg twice daily 1
• Metoprolol succinate: 50-400 mg once daily 1

Critical Contraindications at Any Dose

Absolute contraindications that preclude metoprolol use regardless of dose include: 2, 1

• Signs of heart failure, low output state, or decompensated heart failure
• Second or third-degree AV block without a functioning pacemaker
• Active asthma or severe reactive airway disease
• Symptomatic bradycardia (heart rate <50-60 bpm with symptoms)
• Systolic blood pressure <100 mmHg with symptoms

Important Clinical Considerations

Pharmacokinetic Factors

• Oral bioavailability is approximately 50% due to first-pass metabolism 5
• Poor CYP2D6 metabolizers (8% of Caucasians) exhibit several-fold higher plasma concentrations and may require lower maximum doses 5
• Elimination half-life is 3-4 hours for extensive metabolizers, but 7-9 hours for poor metabolizers 5

Special Populations

• Women may achieve optimal outcomes at 50% of guideline-recommended doses due to 50-80% higher drug exposure compared to men 1
• Elderly women taking 25 mg may have equivalent exposure to 100 mg in healthy young men 1
• Hepatic impairment considerably prolongs elimination half-life (up to 7.2 hours), potentially requiring dose reduction 5
• Renal impairment does not significantly affect pharmacokinetics, so dose adjustment is usually not needed 5

Common Pitfalls to Avoid

• Never use metoprolol tartrate for heart failure management—only metoprolol succinate has proven mortality benefit 1, 3
• Never administer the full 15 mg IV dose as a single rapid bolus—this significantly increases risk of hypotension and bradycardia 1
• Never abruptly discontinue metoprolol—this can cause severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias with 50% mortality in one study 1
• Do not give IV metoprolol to patients with signs of cardiogenic shock, particularly those >70 years, systolic BP <120 mmHg, or heart rate >110 bpm or <60 bpm 1