ACE inhibitors

Question 1

Indications

Answer 1

1. Hypertension: for the first- or second-line treatment of hypertension, to reduce the risk of stroke, myocardial infarction and death from cardiovascular disease.
2. Chronic heart failure: for the first-line treatment of all grades of heart failure, to improve symptoms and prognosis.
3. Ischaemic heart disease: to reduce the risk of subsequent cardiovascular events such as myocardial infarction and stroke.
4. Diabetic nephropathy and chronic kidney disease (CKD) with proteinuria: to reduce proteinuria and progression of nephropathy.

Question 2

Mechanisms of action

Answer 2

ACE inhibitors block the action of the ACE, to prevent the conversion of angiotensin I to angiotensin II. Angiotensin II is a vasoconstrictor and stimulates aldosterone secretion. Blocking its action reduces peripheral vascular resistance (afterload), which lowers blood pressure. It particularly dilates the efferent glomerular arteriole, which reduces intraglomerular pressure and slows the progression of CKD. Reducing the aldosterone level promotes sodium and water excretion. This can help to reduce venous return (preload), which has a beneficial effect in heart failure.

Question 3

Adverse effects

Answer 3

Hypotension
Dry cough
Hyperkalaemia

Question 4

Warnings

Answer 4

ACE inhibitors should be avoided in patients with renal artery stenosis or acute kidney injury; in women who are, or could become, pregnant; and those who are breastfeeding. Although ACE inhibition is potentially valuable in some forms of chronic kidney disease, lower doses should be used and the effect on renal function monitored closely.

Question 5

Interactions

Answer 5

Due to the risk of hyperkalaemia, avoid prescribing ACE inhibitors with other potassium-elevating drugs, including potassium supplements (oral or IV) and potassium-sparing diuretics except under specialist advice for advanced heart failure. In combination with other diuretics they may be associated with profound first-dose hypotension. The combination of an NSAID and an ACE inhibitor increases the risk of renal failure.

Question 6

Prescribing

Answer 6

PO

Question 7

Administration

Answer 7

They can be taken with or without food. It is best to take the first dose before bed to reduce symptomatic hypotension.

Question 8

Communication

Answer 8

Explain that you are offering treatment with a medicine to improve blood pressure and reduce strain on their heart. Advise patients about common side effects such as a dry cough, and about the possibility of dizziness due to low blood pressure, particularly after the first dose. Mention that, very rarely, this medicine can cause effects similar to severe allergic reactions; they should stop taking it and seek urgent medical advice if they develop facial swelling or stomach pains.

Question 9

Monitoring

Answer 9

Monitor efficacy clinically, for example reduced symptoms of breathlessness in heart failure, or improved blood pressure control in hypertension. For safety, check electrolytes and renal function before starting treatment. Repeat these 1–2 weeks into treatment and after increasing the dose.