ACE inhibitors

Question 1

Mechanism of action?

Answer 1

Inhibit the conversion angiotensin I to angiotensin II

Question 2

Which group is this drug less effective in treating?

Answer 2

Hypertensive Afro-Caribbean patients

Question 3

Where are ACE inhibitors activated?

Answer 3

ACE inhibitors are activated by phase 1 metabolism in the liver

Question 4

Side effects?

Answer 4

• cough (occurs in around 15% of patients and may occur up to a year after starting treatment,
  thought to be due to increased bradykinin levels)
• angioedema: may occur up to a year after starting treatment
• hyperkalaemia
• first-dose hypotension: more common in patients taking diuretics

Question 5

Cautions and contraindications?

Answer 5

• pregnancy and breastfeeding - avoid
• renovascular disease - may result in renal impairment
• aortic stenosis - may result in hypotension
• hereditary of idiopathic angioedema
• specialist advice should be sought before starting ACE inhibitors in patients with a potassium >= 5.0 mmol/L

Question 6

What monitoring should be performed?

Answer 6

Urea and electrolytes should be checked before treatment is initiated and after increasing the dose

• a rise in the creatinine and potassium may be expected after starting ACE inhibitors
• acceptable changes are an increase in serum creatinine, up to 30% from baseline and an increase in potassium up to 5.5 mmol/l.
• significant renal impairment may occur in patients who have undiagnosed bilateral renal artery stenosis