Captopril

How it works

It inhibits ACE, reducing the conversion of angiotensin I to angiotensin II and decreasing aldosterone secretion, producing vasodilatation and reduced sodium and water retention.

Prescribing in practice

• Contraindicated in pregnancy due to the risk of fetal toxicity from drugs acting on the renin-angiotensin system.
• Can cause hyperkalaemia, renal impairment and first-dose hypotension, with particular caution in volume depletion, renal artery stenosis and concomitant potassium-sparing agents.
• May cause a persistent dry cough and, rarely, angioedema, which requires immediate discontinuation.

Monitoring

Monitor blood pressure, renal function and serum potassium before and after starting treatment and following dose changes.

Counselling the patient

• Tell your prescriber immediately if you become pregnant, as this medicine must be stopped.
• Report any swelling of the face, lips or throat urgently, and mention a persistent dry cough.

Evidence & guidelines

ACE inhibitors including captopril improve outcomes in heart failure and after myocardial infarction, as shown in landmark trials such as SAVE.