Angiotensin Receptor Blocker (Losartan)

Question 1

What are ARBs (Losartan) used for?

Answer 1

1) Hypertension
2) Chronic heart failure
3) Ischaemic heart disease
4) Diabetic neuropathy
5) CKD with proteinuria

Question 2

How do ARBs (Losartan) work?

Answer 2

ARBs block the action of angiotensin ii on the AT1 receptor.
Angiotensin II is a vasoconstrictor. By blocking its action this reduces the periferal vascular resistance —> lowers BP.
- dilation of afferent glomerular arteriole causes reduced intra glomerlular pressure.
-reduces aldosterone —> reduced Na+ and water retention —> decreased preload.

Question 3

What are the important side effects of ARBs (losartan)?

Answer 3

1) Hypotension
2) Hyperkalaemia
3) Renal failure (those with renal artery stenosis.

Question 4

In what patients should ARBs (Losartan) be avoided?

Answer 4

1) renal artery stenosis
2) acute kidney injury
3) pregnant or breastfeeding

Question 5

what are the potential drug interactions of ARBs (losartan)

Answer 5

1) potassium elevating drugs (e.g. potassium sparing diuretics such spironolactone)
2) NSAIDs (can cause renal failure)

Question 6

What route are ARBs taken>

Answer 6

Orally

Question 7

How is the efficacy of the drug measured?

Answer 7

1) reduced SOB

2) lower BP

Question 8

How do we check safety with ARBs (losartan)?

Answer 8

Monitor electrolytes (hyperkalaemia) and kidney function.

• creatinine should not rise by more than 30%
• eGFR should not fall by more than 25%
• Potassium should not rise over 6.0mmols/L