Makindo Medical Notes

Related Subjects: | Hypertension

⚠️ Important: Drugs that act on the renin–angiotensin system (ACE inhibitors & ARBs) can cause fetal and neonatal morbidity/mortality if given during pregnancy. Always check carefully before prescribing to women of childbearing age.

📖 About

Always check the BNF link here for full prescribing guidance.

• 💊 Olmesartan medoxomil is an angiotensin II receptor blocker (ARB).
• Specifically blocks AT₁ receptors → inhibits vasoconstriction and aldosterone secretion.
• Alternative to ACE inhibitors if intolerant (e.g. cough).

⚙️ Mode of Action

• Blocks angiotensin II from binding to AT₁ receptors.
• ➡️ Vasodilation, reduced aldosterone release, ↓ sodium and water retention.
• Overall effect: ↓ systemic vascular resistance and ↓ blood pressure.

📋 Indications

• 🌡️ Hypertension (first-line in <55 years, or non-black patients if ACEI not tolerated).
• Less effective as monotherapy in black patients (consider calcium-channel blocker instead).
• Can be used in combination with other antihypertensives if monotherapy insufficient.

💊 Dose

• Start: 20 mg OD.
• Maintenance: 20–40 mg OD (max 40 mg daily).
• Adjust dose according to BP response.

🔄 Interactions

• See BNF for full list.
• ⚠️ ↑ Risk of hyperkalaemia with potassium supplements, spironolactone, eplerenone.
• ⚠️ NSAIDs may blunt antihypertensive effect and worsen renal function.
• Combination with aliskiren or ACE inhibitors not routinely recommended.

⛔ Contraindications

• 🚫 Pregnancy (teratogenic).
• 🚫 Breastfeeding (alternative preferred; consider stopping either drug or nursing).
• ⚠️ Hypotension in volume/salt-depleted patients.
• ⚠️ Severe renal impairment or bilateral renal artery stenosis.

⚠️ Side Effects

• 🩺 Renal impairment (monitor U&E, especially creatinine and potassium).
• ⬇️ Hypotension (esp. in dehydrated/diuretic-treated patients).
• 😮‍💨 Cough incidence similar to placebo (unlike ACE inhibitors).
• Rare: hyperkalaemia, dizziness, headache, GI upset.

📝 Clinical Pearls

• Monitor renal function and potassium 1–2 weeks after initiation or dose change.
• Safer alternative to ACE inhibitors in patients with ACEI-induced cough.
• Always ask about pregnancy intentions before starting an ARB.
• If BP uncontrolled, consider dual therapy (ARB + thiazide-like diuretic or calcium-channel blocker).

📚 References

• BNF – Olmesartan
• NICE Hypertension Guidelines (NG136)