Makindo Medical Notes

⚠️ Intravenous metoprolol must only be used with close cardiac and physiological monitoring.

📖 About

Always check the BNF link here for the most up-to-date information.

• 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.