Overview
Irbesartan is an angiotensin II receptor antagonist (ARB) used primarily for the treatment of hypertension and diabetic nephropathy in patients with type 2 diabetes. It works by blocking the vasoconstrictor and aldosterone-secreting effects of angiotensin II.
Mechanism of Action
Irbesartan selectively blocks the binding of angiotensin II to the AT1 receptor, which is found in many tissues including vascular smooth muscle and the adrenal gland. This blockade inhibits the vasoconstrictive and aldosterone-secreting effects of angiotensin II, leading to vasodilation, reduced blood pressure, and decreased sodium and water retention.
Indications
- Hypertension
- Diabetic nephropathy in patients with type 2 diabetes and hypertension
Dosage
Hypertension: Initial dose 150 mg once daily, may be increased to 300 mg once daily. Diabetic nephropathy: Target maintenance dose 300 mg once daily. Dose adjustment may be needed in volume-depleted patients or those with hepatic impairment.
Contraindications
- Hypersensitivity to irbesartan or any component of the formulation
- Pregnancy (second and third trimesters)
- Concomitant use with aliskiren in patients with diabetes
Side Effects
- Dizziness
- Fatigue
- Musculoskeletal pain
- Upper respiratory infection
- Diarrhea
- Dyspepsia
- Hyperkalemia
- Hypotension
- Angioedema (rare)
- Increased serum creatinine
Interactions
- Potassium supplements/potassium-sparing diuretics: Increased risk of hyperkalemia
- NSAIDs: May reduce antihypertensive effect and increase risk of renal impairment
- Lithium: Increased lithium levels
- ACE inhibitors: Increased risk of hyperkalemia, hypotension, and renal dysfunction