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Irbesartan
Irbesartan is an angiotensin II receptor blocker (ARB) widely prescribed for hypertension and diabetic nephropathy. Renowned for its potent and sustained blood pressure-lowering effects, irbesartan is distinguished by its renal protective benefits in diabetic patients. This article synthesizes evidence from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to detail its pharmacology, clinical applications, and safety profile.
Irbesartan selectively antagonizes angiotensin II type 1 (AT₁) receptors, blocking the vasoconstrictive and aldosterone-secreting effects of angiotensin II. Key outcomes include:
- Vasodilation: Reduced systemic vascular resistance and blood pressure.
- Renal Protection: Decreased glomerular pressure and proteinuria, slowing progression of diabetic nephropathy (Lippincott Textbook of Pharmacology).
- Aldosterone Suppression: Limits sodium/water retention and potassium excretion (Lange Basic & Clinical Pharmacology).
Irbesartan’s high receptor affinity and long half-life (11–15 hours) enable once-daily dosing and sustained 24-hour efficacy (BNF).
- Hypertension:
- First-line monotherapy or combined with thiazides/calcium channel blockers.
- Diabetic Nephropathy:
- Slows progression of kidney disease in type 2 diabetes with hypertension (e.g., IDNT trial) (BNF).
- Off-Label:
- Heart failure with reduced ejection fraction (HFrEF) in ACE inhibitor-intolerant patients.
- Hypertension:
- Adults: 150 mg once daily, increased to 300 mg daily if needed.
- Elderly: No initial adjustment, but monitor for hypotension.
- Diabetic Nephropathy: 300 mg once daily.
- Renal/Hepatic Impairment:
- Renal (eGFR <30 mL/min): Start at 75 mg daily; max 300 mg daily.
- Hepatic Cirrhosis: Avoid in severe impairment (BNF).
- Dizziness, fatigue, hyperkalemia, orthostatic hypotension.
- Mild gastrointestinal disturbances (nausea, diarrhea).
Serious (Rare):
- Angioedema: Facial/tongue swelling (discontinue immediately).
- Acute Kidney Injury: Monitor creatinine in renal impairment.
- Hypotension: Risk in volume-depleted patients (Lange Basic & Clinical Pharmacology).
- Contraindications:
- Pregnancy (Category D: fetal harm in second/third trimesters).
- Bilateral renal artery stenosis, severe hepatic impairment.
- Monitoring:
- Serum potassium, renal function, and blood pressure.
- Avoid dehydration and high-potassium diets.
- Pregnancy/Lactation:
- Lactation: Excreted in breast milk; avoid (BNF).
- Potassium-Sparing Diuretics (e.g., spironolactone): Increased hyperkalemia risk.
- NSAIDs (e.g., ibuprofen): Reduce antihypertensive efficacy; nephrotoxicity risk.
- Lithium: Elevated lithium levels (monitor toxicity).
- ACE Inhibitors: Avoid combination (additive hyperkalemia/renal risks) (Lippincott Textbook of Pharmacology).
- Generic: Irbesartan.
- Brand Names: Avapro® (US), Aprovel® (EU), Karvea® (AU).
- Combination Products: Irbesartan/hydrochlorothiazide (e.g., CoAprovel®).
