Metoprolol
Selective Beta-1 Adrenergic Blocker
Generic Name
Metoprolol
Drug Class
Beta-1 selective adrenergic blocker (cardioselective beta-blocker)
Indications
- Hypertension
- Angina pectoris
- Heart failure (selected patients)
- Post-myocardial infarction
- Supraventricular tachycardia
Dosage
- Hypertension: 50–100 mg orally once daily (immediate release) or 100–200 mg/day (extended release)
- Angina pectoris: 50 mg orally 2–3 times daily, titrate as tolerated
- Heart failure: Start 12.5–25 mg once daily, titrate to target dose (e.g., 200 mg/day extended release)
- Post-MI: 25–50 mg orally every 6–12 hours initially; titrate as tolerated
Note: Adjust dose in hepatic impairment; monitor heart rate and blood pressure.
Route of Administration
Oral (immediate-release tablet, extended-release tablet), IV (for selected indications)
Mechanism of Action
Metoprolol selectively blocks beta-1 adrenergic receptors in the heart, reducing heart rate, myocardial contractility, and cardiac output. This lowers blood pressure and decreases myocardial oxygen demand.
Common Adverse Effects
- Fatigue
- Dizziness
- Bradycardia
- Hypotension
- Cold extremities
Serious Adverse Effects
- Severe bradycardia or AV block
- Heart failure exacerbation
- Hypotension
- Bronchospasm (rare, less than non-selective beta-blockers)
Contraindications
- Severe bradycardia
- Second- or third-degree AV block
- Cardiogenic shock
- Severe hypotension
- Hypersensitivity to metoprolol
Precautions
- Monitor heart rate and blood pressure
- Use with caution in asthma, diabetes, and severe peripheral vascular disease
- Gradually taper if discontinuing therapy to avoid rebound hypertension or angina
Drug Interactions
- Other antihypertensives – additive hypotensive effect
- Antiarrhythmics – increased risk of bradycardia or AV block
- Insulin or oral hypoglycemics – may mask hypoglycemia
- CYP2D6 inhibitors – may increase metoprolol plasma levels
Pregnancy & Lactation
Use with caution in pregnancy and breastfeeding; monitor fetal and neonatal heart rate and blood pressure.
Patient Counseling
- Take at the same time each day
- Do not stop therapy abruptly
- Monitor heart rate and blood pressure regularly
- Report dizziness, fainting, or shortness of breath