Angiotensin receptor blockers (ARBs)

Question 1

Name some examples of ARBs

Answer 1

1. Losartan
2. Candesartan
3. Irbesartan
4. Sacubitril valsartan (Entresto)

Question 2

What are the indications of ARBs?

Answer 2

1. Hypertension
2. Chronic heart failure
3. Diabetic Nephropathy - reduce progression of nephropathy
4. Chronic Kidney Disease (CKD) with proteinuria - reduce proteinuria

Question 3

What is the MOA?

Answer 3

ARBs block the action of Angiotensin 2 on the Angiotensin type 1 receptor.

Angiotensin 2 is a vasoconstrictor and stimulates Aldosterone secretion. Blocking Angiotensin 2 in:

• HTN: vasodilation > lowers BP
• CKD: vasodilation of efferent glomerular arteriole > lower intraglomerular pressure, which slows progression of CKD
• Chronic heart failure: Reducing aldosterone concentration promotes sodium and water excretion > reduce venous return (preload) > reduce EF

Question 4

What are the side effects?

Answer 4

1. Hypotension (particularly after the first dose)
2. Hyperkalemia (because a lower Aldosterone level promotes K+ retention)
3. Worsening renal failure (particularly in Renal artery stenosis, as vasoconstriction of the efferent glomerular arteriole is needed to maintain glomerular filtration)

Question 5

Why are ARBs preferred in black people?

Answer 5

ARBs are less likely to cause Angioedema and cough because it does not affect bradykinin metabolism.

Question 6

What are the contraindications of ARBs?

Answer 6

• Renal artery stenosis
• Acute Kidney Injury (AKI)
• women who are breastfeeding or pregnant
• Caution in CKD (give at a lower dose & monitor renal function)

Question 7

Which drugs interact with ARBs negatively?

Answer 7

• Potassium-elevating drugs (potassium supplements, aldosterone antagonists, potassium-sparing diuretics)
• NSAID with an ARB increases the risk of nephrotoxicity

Question 8

How do you monitor a person on ARBs?

Answer 8

Get a baseline U&E before starting and repeat 1-2 weeks into treatment and after increasing dose.