Makindo Medical Notes

💊 About: Always check the BNF link here

• 🔹 Angiotensin II receptor blocker (ARB) – mainly an AT1 antagonist.

⚙️ Action

• There are two angiotensin II receptors: AT1 and AT2.
• 🩸 AT1 receptor → vasoconstriction and aldosterone release.
• 🚫 Irbesartan blocks AT1 → vasodilation + ↓ aldosterone → reduced BP and afterload.
• 📉 Benefits in heart failure, hypertension, and proteinuric renal disease.
• ℹ️ Unlike losartan, irbesartan is not a prodrug.

🎯 Indications / Dose

• ❤️ Hypertension (first-line in certain groups, e.g. Afro-Caribbean if ACEI not tolerated).
• 💔 Heart failure (HFrEF) – start low, titrate slowly.
• 🧪 Prevention/treatment of diabetic nephropathy and CKD with proteinuria.
• ➡️ Starting dose: 75–150 mg PO OD.
• ➡️ Maintenance range: titrate slowly to max 300 mg PO OD.

⛔ Contraindications

• 🚫 Pregnancy – teratogenic, risk of birth defects.
• ⚠️ Severe aortic stenosis or hypertrophic cardiomyopathy (risk of collapse).
• 🚫 Bilateral renal artery stenosis or severe renal impairment.

🔄 Interactions

• May be used as an alternative to ACE inhibitors (often chosen if ACEI cough develops).
• ⬆️ Risk of hyperkalaemia with potassium-sparing diuretics, supplements, or dual RAAS blockade.

⚠️ Side Effects

• 🧪 Hyperkalaemia (monitor closely, especially in CKD).
• 💨 No cough (advantage over ACE inhibitors).
• Rare: dizziness, hypotension, renal impairment, angioedema (less common than with ACEIs).

📋 Monitoring

• 🔍 Check renal function and electrolytes 4 days and 2 weeks after initiation.
• 📈 Recheck 1 week after any dose increase.
• ⚠️ Stop or reduce dose if creatinine ↑ >30% or K⁺ >6.0 mmol/L.

📚 References

• Irbesartan – BNF