Angiotensin Converting Enzyme Inhibitors

Commonly Lisinopril/Ramipril

Mechanism of Action

  • Inhibit the conversion of angiotensin I to angiotensin II
    • Angiotensin II is a potent vasoconstrictor, promotes aldosterone release (which further increases blood pressure via increased sodium/water reabsorption) and facilitates sympathetic activity
  • NB ACEIs act synergistically with diuretics (which partly activate the RAAS)


  • Heart failure (usually in combination with a beta-blocker, usually bisoprolol)
    • Usually start low(ish) dose
  • Hypertension in younger people (except Afro-Caribbean patients)
  • Diabetic nephropathy
  • Post MI (secondary prophylaxis)
  • Post stroke/TIA (usually perindopril)


  • Check renal function and FBC prior to initiation/increasing dose (risk of hyperkalaemia; agranulocytosis in collagen vascular disease)
  • Potassium supplements/Potassium sparing diuretics should be stopped (or decreased dose) prior to initiation of ACEIs (risk of hyperkalaemia)
  • Profound first dose hypotension may occur in patients already taking diuretics (particularly high dosages- use with caution)
  • Use with caution in patients with
    • Hypovolaemia; hyponatraemia; hypotension; unstable heart failure; receiving high dose vasodilator treatment; known renovascular disease (unilateral) OR other peripheral vascular disease (increased risk of renovascular disease)
  • In general, DO NOT co-prescribe NSAIDs (risk of renal injury)
  • In severe liver dysfunction, there is a small risk of hepatic necrosis so should be avoided or closely monitored (likewise, if liver function deteriorates in otherwise healthy individuals, discontinue)
  • In renal dysfunction, monitor closely for any deterioration or hyperkalaemia


  • Bilateral renal artery stenosis (reduce GFR and can precipitate renal failure)
  • Severe/symptomatic aortic stenosis (decreased BP could decrease cardiac output and precipitate heart failure)
  • Hypersensitivity

Side effects (NB Most are well-tolerated)

  • Profound hypotension- Particularly on first doses (if this is the case, reduce dose and increase as required later)
  • Renal Impairment
  • Dry cough
  • Hypersensitivity- angioedema (more common than most drugs; onset may be delayed; more common in Afro-Caribbeans); rash
  • Pancreatitis
  • URTIs e.g. sinusitis; rhinitis; sore throat
  • GI- nausea, vomiting; dyspepsia; diarrhoea; constipation; abdominal pain; deranged LFTs; jaundice; hepatitis; fulminant hepatic necrosis; hepatic failure
  • Hyperkalaemia; hypoglycaemia
  • Thrombocytopenia; leucopenia; neutropenia; haemolytic anaemia
  • Taste disturbance and skin rashes

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