ABISART

What it is

Abisart is a specific antagonist of angiotensin II receptors (AT1 subtype). It blocks the potent vasoconstrictor and aldosterone-secreting effects of angiotensin II by selective antagonism of the angiotensin II (AT1 subtype) receptors localised on vascular smooth muscle cells and in the adrenal cortex.

Approved indications

— Treatment of hypertension. — Delaying the progression of renal disease in hypertensive type II diabetics with persistent micro-albuminuria (≥ 30 mg per 24 hours) or urinary protein in excess of 900 mg per 24 hours.

Dosing overview

The usual initial and maintenance dose of Abisart is 150 mg once daily. Patients requiring further reduction in blood pressure should have the dose increased to 300 mg once daily. In patients with hypertension and type II diabetic renal disease 300 mg of irbesartan once daily is the preferred maintenance dose. Abisart may be administered with or without food.

Key safety warnings

Irbesartan has been rarely associated with hypotension in hypertensive patients without other co-morbid conditions. Symptomatic hypotension, as with ACE inhibitors, may be expected to occur in sodium/volume depleted patients such as those treated vigorously with diuretics and/or salt restriction, or on haemodialysis. As a consequence of inhibiting the renin-angiotensin-aldosterone system, changes in renal function may be anticipated in susceptible individuals. In patients whose renal function depends on the activity of the renin-angiotensin-aldosterone system (e.g., hypertensive patients with renal artery stenosis in one or both kidneys, or patients with severe congestive heart failure), treatment with drugs that affect this system has been associated with oliguria and/or progressive azotemia and (rarely) with acute renal failure and/or death. The possibility of a similar effect occurring with the use of an angiotensin II receptor antagonist, including irbesartan cannot be excluded. Irbesartan increases the risk of significant hyperkalaemia in hypertensive patients with type II diabetes and moderate to severe renal insufficiency. Serum potassium should be monitored regularly in such patients. Intestinal angioedema has been reported in patients treated with angiotensin II receptor antagonists, including Abisart. These patients presented with abdominal pain, nausea, vomiting and diarrhoea. Symptoms resolved after discontinuation of angiotensin II receptor antagonists. Irbesartan may induce hypoglycaemia, particularly in patients treated for diabetes. Therefore, dose adjustment of antidiabetic treatment such as repaglinide or insulin may be required.

Contraindications

Abisart is contraindicated in patients who are hypersensitive to irbesartan or to any other component of the irbesartan formulation. Do not co-administer Abisart with aliskiren-containing medicines in patients with diabetes or with moderate to severe renal impairment. Do not co-administer Abisart with ACE inhibitors in patients with diabetic nephropathy.

Regulatory history

Abisart 75 mg, 150 mg, and 300 mg tablets were first registered on the Australian Register of Therapeutic Goods on 30 October 2018.