1. Introduction
Metoprolol is a beta-1 selective adrenergic receptor blocker (beta-blocker) commonly used to treat hypertension, angina, heart failure, and arrhythmias. It works by reducing heart rate, cardiac output, and blood pressure, making it beneficial for cardiovascular conditions. Metoprolol is available in two forms: metoprolol tartrate (immediate-release) and metoprolol succinate (extended-release).
2. Indications
- Hypertension (high blood pressure)
- Angina pectoris (chest pain)
- Heart failure (chronic, stable, with reduced ejection fraction)
- Myocardial infarction (acute or prevention of recurrence)
- Arrhythmias (e.g., atrial fibrillation, supraventricular tachycardia)
- Migraine prophylaxis (off-label)
3. Dosage
Adults:
- Hypertension:
- Immediate-release: 50–100 mg twice daily.
- Extended-release: 25–100 mg once daily, up to a maximum of 400 mg/day.
- Angina:
- Immediate-release: 50–200 mg/day in divided doses.
- Extended-release: 100–400 mg once daily.
- Heart failure:
- Start with 12.5–25 mg of extended-release once daily, titrated up to 200 mg/day.
- Myocardial infarction (post-acute):
- Immediate-release: 50 mg every 6 hours for 48 hours, then switch to maintenance (100 mg twice daily).
Children (≥6 years):
- Hypertension:
- Extended-release: Start with 1 mg/kg once daily (maximum 50 mg/day), titrated as needed.
4. Administration
- Immediate-release tablets should be taken with or immediately after meals.
- Extended-release tablets can be taken with or without food; do not crush or chew.
- Administer consistently at the same time each day for optimal effectiveness.
5. Forms Available
- Immediate-release tablets: 25 mg, 50 mg, 100 mg
- Extended-release tablets: 25 mg, 50 mg, 100 mg, 200 mg
- Injectable solution: 1 mg/mL
6. Side Effects
6.1 Common Side Effects:
- Fatigue
- Dizziness or light-headedness
- Slow heart rate (bradycardia)
- Cold extremities
- Nausea
6.2 Less Common Side Effects:
- Insomnia
- Depression
- Shortness of breath (mild bronchospasm)
- Erectile dysfunction
6.3 Rare but Serious Side Effects:
- Severe bradycardia or heart block
- Hypotension (low blood pressure)
- Worsening heart failure
- Severe bronchospasm (especially in patients with asthma or COPD)
7. Warnings
- Abrupt Withdrawal: Avoid sudden discontinuation as it may cause rebound hypertension, angina, or myocardial infarction. Taper gradually over 1–2 weeks.
- Bradycardia: Use cautiously in patients with existing bradycardia or heart block.
- Asthma or COPD: May worsen bronchospasm, even though beta-1 selectivity reduces this risk.
8. Precautions
- Use cautiously in patients with diabetes, as metoprolol may mask hypoglycaemia symptoms (e.g., tachycardia).
- Avoid in patients with untreated pheochromocytoma without concurrent alpha-blocker use.
- Monitor for worsening depression or fatigue during long-term use.
9. Interactions
- Calcium channel blockers (e.g., verapamil, diltiazem): Increased risk of bradycardia and heart block.
- Digoxin: Increased risk of bradycardia.
- NSAIDs: May reduce antihypertensive effects.
- CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): May increase metoprolol plasma levels and toxicity.
- Insulin or oral antidiabetics: May mask hypoglycaemia symptoms.
10. Monitoring Parameters
- Monitor blood pressure and heart rate regularly.
- Assess for symptoms of heart failure (e.g., weight gain, oedema, dyspnoea).
- Monitor blood glucose in diabetic patients.
- ECG monitoring during intravenous administration.
11. Use in Children
- Approved for hypertension in children ≥6 years.
- Not recommended for other conditions unless under specialist supervision.
12. Use in Pregnancy
- Classified as Category C (risk cannot be ruled out). Use only if benefits outweigh potential risks. Close fetal monitoring is recommended due to the risk of intrauterine growth restriction or neonatal bradycardia.
13. Use in Elderly
- Start with lower doses due to increased sensitivity to beta-blockers and the risk of bradycardia or hypotension.
14. Use in Kidney Disease
- No dosage adjustment required. Metoprolol is primarily metabolised by the liver.
15. Use in Liver Disease
- Use cautiously in patients with hepatic impairment, as metoprolol is metabolised in the liver. Dose adjustments may be needed.
16. Patient Counselling Points
- Take metoprolol at the same time every day as directed.
- Do not stop taking metoprolol abruptly without consulting your doctor.
- Report any symptoms of dizziness, slow heart rate, or swelling in the legs or feet.
- Avoid alcohol as it may increase the risk of side effects like dizziness.
- For diabetic patients: Be aware that metoprolol may mask hypoglycaemia symptoms like a racing heart.
17. Table of Brand Names, Manufacturer, and Prices in USD
Brand Name | Manufacturer | Strength/Dosage Form | Price (USD) |
---|---|---|---|
Lopressor | Novartis | 50 mg Immediate-Release | $15 (30 tablets) |
Toprol XL | AstraZeneca | 100 mg Extended-Release | $30 (30 tablets) |
Generic Metoprolol | Various | 50 mg Immediate-Release | $10 (30 tablets) |
Betaloc | AstraZeneca | 5 mg/mL Injectable Solution | $20 (10 ampoules) |
18. 15 FAQs (Frequently Asked Questions)
1. What is Metoprolol?
Metoprolol is a beta-blocker used to treat high blood pressure, angina, heart failure, and arrhythmias.
2. How does Metoprolol work?
It blocks beta-1 adrenergic receptors, slowing the heart rate and reducing the workload on the heart.
3. What is the difference between Metoprolol tartrate and Metoprolol succinate?
Metoprolol tartrate is an immediate-release formulation taken multiple times daily, while metoprolol succinate is an extended-release formulation taken once daily.
4. What is the usual dose of Metoprolol?
Doses range from 25–200 mg daily depending on the condition being treated.
5. Can Metoprolol be taken during pregnancy?
Metoprolol is used cautiously in pregnancy due to potential risks like fetal growth restriction.
6. Is Metoprolol safe for children?
Yes, it is approved for hypertension in children ≥6 years.
7. Can Metoprolol cause weight gain?
Weight gain is not a common side effect, but fluid retention in heart failure patients may occur.
8. What are the most common side effects of Metoprolol?
Fatigue, dizziness, and bradycardia are common side effects.
9. Can Metoprolol be stopped abruptly?
No, stopping it suddenly can cause rebound hypertension, angina, or heart attack. Tapering is advised.
10. Can Metoprolol interact with other medications?
Yes, it interacts with calcium channel blockers, digoxin, NSAIDs, and antidiabetics.
11. How should Metoprolol be stored?
Store at room temperature away from moisture and heat.
12. Can Metoprolol be used in asthma patients?
Use with caution as it may cause bronchospasm, although its beta-1 selectivity reduces this risk.
13. Can Metoprolol cause erectile dysfunction?
Yes, erectile dysfunction is a possible side effect.
14. How quickly does Metoprolol work?
Immediate-release formulations start working within 1–2 hours, while extended-release takes effect within a day.
15. Is Metoprolol a lifelong medication?
It depends on the condition. For chronic diseases like hypertension or heart failure, long-term use may be required.