ACE Inhibitors

ACE inhibitors prevent the conversion of angiotensin I to angiotensin II by angiotensin converting enzyme (ACE) in the lungs, in turn reducing effects of angiotensin II. These effects include:

  • Vasoconstriction
  • Noradrenaline reuptake inhibition
  • Thirst
  • ADH release
  • ACTH release
  • Aldosterone release
  • Reduces Kf, reducing GFR

Indications

  • Hypertension
    • Particularly in insulin dependent diabetes with diabetic nephropathy
    • Less effective for this indication in the black population
    • Contribute to post-operative hypertension and may be witheld perioperatively
  • Cardiac failure
    All grades.
  • MI with LV dysfunction
    Improved prognosis.

Classification

Can be divided into three groups based on pharmacokinetics:

  • Active drug with active metabolites
    Captopril.
  • Prodrug
    Ramipril.
  • Not metabolised and excreted unchanged in urine
    Lisinopril.

Common Features of ACE Inhibitors

Property Drug
Resp Bradykinin cough
CVS SVR and BP. Unaffected HR and baroreceptor response.
Endocrine Hypoglycaemia in diabetics
Renal With a normal renal perfusion pressure, natriuresis results. However, a fall in renal perfusion pressure may cause pre-renal failure (e.g. renal artery stenosis).
Haeme Agranulocytosis, thrombocytopenia
Immune Angioedema
Metabolic ↑ Renin release.
Interactions ↓ Aldosterone release, which ↑ the efficacy of spironolactone and may precipitate hyperkalaemia. Pharmacodynamic interaction with NSAIDs to drop renal perfusion pressure.

References

  1. Peck TE, Hill SA. Pharmacology for Anaesthesia and Intensive Care. 4th Ed. Cambridge University Press. 2014.
Last updated 2017-10-07

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