AT1 blockers/ ARBs

Question 1

Give some examples of angiotensin receptor blockers (ARBs)

Answer 1

• Losartan, candesartan, irbesartan

Question 2

What are the indications for use

Answer 2

• When ACE-i not tolerated due to cough
• HTN (reduce risk stroke, MI, CVD death)
• Chronic HF
• IHD
• Diabetic nephropathy + CKD w. proteinuria - reduce proteinuria + progression nephropathy

Question 3

What are the mechanisms of action

Answer 3

• Similar effect to ACE-i
• But block action of angiotension 2 at AT1 receptor
• Ang2 = vasoconstrictor + stim aldosterone secretion
• Blocking = reduced peripheral vasc resistance (afterload) = lower BP
• Dilates efferent glomerular arteriole (reduce pressure + slows CKD)
• Reducing aldosterone = Na + H2O excretion –> help reduce preload (beneficial in HF)

Question 4

What are the side effects of ARBs

Answer 4

• Hypotension (particularly after 1st dose)
• Hyperkalaemia
• Renal failure (renal artery stenosis most at risk)
• However unlike ACEi do not cause dry cough or angioedema

Question 5

What are some contra-indications

Answer 5

• Renal artery stenosis
• AKI
• Pregnancy/ Breastfeeding
• CKD - lower doses

Question 6

What are some interactions

Answer 6

• Potassium elevating drugs (K+ supplements + K sparing diuretics) due to risk of hyperkalaemia