What is the recommended dosing for Metoprolol (Metoprolol ER) in patients with hypertension, angina, or heart failure, considering comorbidities such as asthma or chronic obstructive pulmonary disease (COPD)?

Metoprolol ER Dosing

For hypertension, start metoprolol succinate (extended-release) at 50 mg once daily and titrate every 1-2 weeks to a target of 200 mg daily; for heart failure, start at 12.5-25 mg once daily with the same target; patients with asthma or COPD should generally avoid metoprolol, but if absolutely necessary, use the lowest possible dose with close monitoring for bronchospasm. 1

Condition-Specific Dosing Protocols

Hypertension

• Initial dose: Metoprolol succinate 50 mg once daily 1
• Titration: Increase dose every 1-2 weeks based on blood pressure response 1
• Target dose: 200 mg once daily 1
• Maximum dose: 400 mg daily 1
• Blood pressure goal: <130/80 mmHg per current guidelines 1

Angina Pectoris

• Initial dose: Metoprolol tartrate 25-50 mg twice daily OR metoprolol succinate 50 mg once daily 1
• Titration: Increase gradually every 1-2 weeks as tolerated 2
• Target dose: 200 mg daily (divided for tartrate, once daily for succinate) 2
• Therapeutic range: 100-400 mg daily has demonstrated antianginal efficacy 3

Heart Failure with Reduced Ejection Fraction

• Critical prerequisite: Patient must be clinically stable without signs of marked fluid retention or need for IV inotropic therapy 2
• Background therapy required: ACE inhibitor (if not contraindicated) 2
• Initial dose: Metoprolol succinate 12.5-25 mg once daily 2, 1
• Titration schedule: Double the dose every 1-2 weeks if the preceding dose was well tolerated 2
• Target dose: 200 mg once daily 2, 1
• Minimum effective dose: At least 100 mg daily (50% of target) should be achieved for optimal mortality reduction 1

Special Populations and Comorbidities

Asthma or COPD

• Strong recommendation: Patients with suspicion of bronchial asthma or severe pulmonary disease should be referred for specialist care before initiating beta-blocker therapy 2
• Absolute contraindication: Active asthma or reactive airways disease is an absolute contraindication to metoprolol 1
• If beta-blocker is deemed essential: Start with the absolute lowest dose (12.5 mg) rather than completely avoiding, but only under specialist supervision 1
• Monitoring: Auscultate for bronchospasm at each visit, particularly during dose titration 1
• Rationale for caution: While metoprolol is beta-1 selective, this selectivity is dose-dependent and lost at higher doses, increasing risk of beta-2 mediated bronchoconstriction 4

Post-Myocardial Infarction

• Timing: Can be initiated early (IV then oral) or later (oral only) depending on hemodynamic stability 3
• IV protocol (if hemodynamically stable): 5 mg IV over 2 minutes, repeated every 5 minutes for up to 3 doses (15 mg total) 1
• Oral transition: Start metoprolol tartrate 50 mg every 6 hours beginning 15 minutes after last IV dose 1
• Long-term maintenance: Transition to metoprolol succinate 200 mg once daily for secondary prevention 1

Atrial Fibrillation Rate Control

• Initial dose: Metoprolol tartrate 25-100 mg twice daily OR metoprolol succinate 50-400 mg once daily 1
• Target heart rate: 50-80 bpm at rest (strict control) or <110 bpm (lenient control) 1
• IV option for acute rate control: 5 mg IV over 1-2 minutes, repeated every 5 minutes up to 15 mg total 1

Critical Contraindications (Any Indication)

Absolute Contraindications

• Signs of heart failure, low output state, or decompensated heart failure 1
• Second or third-degree AV block without functioning pacemaker 1
• Active asthma or severe reactive airway disease 1
• Symptomatic bradycardia (heart rate <50-60 bpm with symptoms) 1
• Systolic blood pressure <100 mmHg with symptoms 1
• Cardiogenic shock or high risk factors (age >70, SBP <120 mmHg, HR >110 or <60 bpm) 1

Titration and Monitoring Protocol

During Dose Escalation

• Frequency: Monitor heart rate, blood pressure, and clinical status at each visit during titration 2
• Interval between increases: Minimum 1-2 weeks to assess tolerance 2
• Signs requiring dose reduction: Worsening heart failure symptoms, symptomatic hypotension, or symptomatic bradycardia 2

Management of Adverse Effects During Titration

• If worsening heart failure symptoms: First increase diuretic dose or ACE inhibitor; temporarily reduce metoprolol dose only if necessary 2
• If hypotension: First reduce vasodilator dose; reduce metoprolol only if necessary 2
• If symptomatic bradycardia: Reduce or discontinue other rate-lowering drugs first; reduce metoprolol dose only if clearly necessary 2
• Key principle: Always consider reintroduction and uptitration when patient becomes stable 2

Common Pitfalls to Avoid

• Never abruptly discontinue metoprolol: This can cause severe exacerbation of angina, myocardial infarction, ventricular arrhythmias, and has been associated with 50% mortality in one study 1
• Don't give full IV dose as rapid bolus: The 15 mg maximum IV dose must be given as three separate 5 mg boluses over 5-minute intervals, never as a single rapid injection 1
• Don't use IV metoprolol in decompensated heart failure: This significantly increases risk of cardiogenic shock 1
• Don't assume beta-1 selectivity is absolute: At higher doses, metoprolol loses its cardioselectivity and can cause bronchospasm even in patients without severe lung disease 4
• Don't start at high doses in heart failure: The "start low, go slow" principle is critical—beginning at 12.5-25 mg prevents acute decompensation 2, 1

Sex-Specific Considerations

• Women may require lower doses: Metoprolol exposure is 50-80% higher in women than men, and women with heart failure may achieve optimal outcomes at 50% of guideline-recommended doses 1
• Elderly women: 15 mg in elderly women produces similar drug exposure to 50 mg in healthy young men 1