2. Losartan

Question 1

drug class

Answer 1

Angiotensin II receptor antagonists

Question 2

What is it used for?

Answer 2

Used in both the treatment of hypertension and heart failure

Question 3

Mechanism of action

Answer 3

They block angiotensin receptor 1 which prevents angiotensin II from binding. This leads to a reduced effect of angiotensin II.
- Reduced vasoconstriction, sympathetic activity and reduced release of ADH and aldosterone

Question 4

Important adverse drug reactions

Answer 4

Hypotension!
hyperkalaemia (low aldosterone ↑K+)
cause or worsen renal failure

Question 5

Important drug-drug interactions

Answer 5

↑K+ drugs, NSAIDs

Question 6

warnings, contraindications

Answer 6

Renal artery stenosis, AKD, pregnancy, (CKD - caution)

Question 7

how do Angiotensin II receptor antagonists differ to ACEi?

Answer 7

• no effect on bradykinin - less effective in low-renin hypertensive patients - dry cough and angioedema much less likely than with ACEi
• Directly targeting AT1 receptors - more effective at inhibiting Ang-II mediated vasoconstriction
than ACEi (remember chymase produces Ang-II aswell – ARB block further downstream in the pathway which is not blocked by ACEi)