Beta-blocker: blocks β-adrenergic receptors in heart, vessels, lungs, pancreas, and liver.
Cardioselective (β1 > β2), but at higher doses may affect β2 receptors.
Useful for rapid IV rate control due to its short half-life.

🎯 Indications

🩸 Hypertension → reduces cardiac output, lowers renin activity.
❤️ Angina → reduces myocardial oxygen demand (⚠️ avoid with verapamil).
🫀 Post-MI (STEMI/NSTEMI) → reduces mortality.
💓 Atrial fibrillation (rate control) → reduces automaticity and AV conduction; can be used with or instead of digoxin.
🔥 Thyrotoxicosis → controls adrenergic symptoms (tachycardia, tremor).
😰 Anxiety and benign essential tremor.
🧠 Migraine prophylaxis.

💊 Dosing Metoprolol (Oral unless specified)

🩸 Hypertension: 100–200 mg once daily (rarely up to 400 mg).
❤️ Angina: 50–100 mg twice or three times daily.
💓 Arrhythmias (rate control): 50–100 mg twice or three times daily.
🧠 Migraine prophylaxis: 50–100 mg twice daily.
🔥 Hyperthyroidism: 50 mg four times daily.
🫀 Post-MI: 5 mg slow IV every 5 min as tolerated (max 10–15 mg). Then switch to oral (e.g. bisoprolol once daily) for maintenance.
⚡ Fast AF: 1–5 mg IV bolus at ≤1 mg/min. Reassess after 5 min; repeat if needed (max 10–15 mg). Then start oral β-blocker (e.g. bisoprolol 2.5 mg OD, titrated as tolerated).

💓 Metoprolol in Atrial Fibrillation

Preferred IV β-blocker for acute rate control due to short half-life.
Give 1–5 mg IV bolus (≤1 mg/min), reassess after 5 min, repeat if tolerated (max 15 mg).
If stable → administer 25 mg orally and commence regular oral therapy (e.g. bisoprolol 2.5 mg OD, titrated up to 20 mg OD).

⛔ Contraindications

Bradycardia (<60 bpm), systolic BP <100 mmHg.
Asthma or bronchospasm 🫁.
Second or third-degree heart block.
Uncontrolled heart failure or acute decompensation.
Severe hypotension.
Phaeochromocytoma (unless α-blockade established).
Sick sinus syndrome.
Significant peripheral vascular disease 🦵.
⚠️ Concomitant verapamil use (risk of heart block/asystole).
Caution in diabetes (masks hypoglycaemia and worsens control).

⚠️ Side Effects

Fatigue, lethargy, cold peripheries 🥶.
Bradycardia, postural hypotension, dizziness.
Worsening heart failure.
Claudication, impotence, insomnia.
Worsening diabetic control.
May exacerbate psoriasis.

📚 References

BNF – Metoprolol
ESC Guidelines – AF and ACS.
Oxford Handbook of Clinical Medicine.

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Metoprolol 💊

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