Makindo Medical Notes

💊 About: Always check the BNF link here

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

⚙️ Action

• There are two angiotensin II receptors: AT1 and AT2.
• 🩸 AT1 receptor → vasoconstriction + aldosterone release.
• 🚫 Losartan blocks AT1 receptor → vasodilation + reduced aldosterone.
• 📉 Results in lower blood pressure and reduced afterload.
• ℹ️ Losartan is a prodrug, converted to active metabolite by the liver.

🎯 Indications / Dose

• ❤️ Hypertension.
• 💔 Heart failure with reduced ejection fraction.
• 🧪 Prevention and treatment of diabetic nephropathy (especially with proteinuria).
• ➡️ Typical initiation: Losartan 25–50 mg PO OD.
• ➡️ Maintenance range: titrate up slowly to max 100 mg PO OD (adjusted for renal function and BP).

⛔ Contraindications

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

🔄 Interactions

• May be used instead of or with ACE inhibitors (avoid dual blockade unless specialist indication).
• ⬆️ Risk of hyperkalaemia with potassium-sparing diuretics, supplements, or ARBs/ACEI combinations.

⚠️ Side Effects

• 🧪 Hyperkalaemia (monitor K⁺, particularly in CKD).
• 💨 Unlike ACE inhibitors, not typically associated with cough.
• Rare: dizziness, hypotension, renal impairment.

📋 Monitoring

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