ACE inhibitors

Question 1

What is the role of ACE inhibitors?

Answer 1

• First-line treatment in younger patients with hypertension
• Extensively used to treat heart failure
• Less effective in treating hypertensive Afro-Caribbean patients
• Diabetic nephropathy
• Secondary prevention of ischaemic heart disease

Question 2

What is the mechanism of action for ACEi?

Answer 2

• inhibit the conversion angiotensin I to angiotensin II
• ACE inhibitors are activated by phase 1 metabolism in the liver

Question 3

What are the side effects of ACEi?

Answer 3

1. 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
2. angioedema: may occur up to a year after starting treatment
3. hyperkalaemia
4. first-dose hypotension: more common in patients taking diuretics

Question 4

What are the cautions and contraindications?

Answer 4

• pregnancy and breastfeeding - avoid
• renovascular disease - significant renal impairment may occur in patients who have undiagnosed bilateral renal artery stenosis
• 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 5

What do you monitor when using ACEi?

Answer 5

• 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*

Question 6

What interactions do ACEi have?

Answer 6

• patients receiving high-dose diuretic therapy (more than 80 mg of furosemide a day)
  
  • significantly increases the risk of hypotension