ACE inhibitors

ANGIOTENSIN CONVERTING ENZYME INHIBITORS

ACE inhibitors like teprotide, captopril, enalapril, Lisinopril, Perindopril, Rampiril

Teprotide - synthesized from bradykinin potentiating factor found in pit viper venom was the first ACE inhibitor which is a nanopeptide with brief duration of action.

Captopril- Orally active dipeptide analogue is a prototype of ACE inhibitor.

  • Abolishes pressor action of Angiotensin I but not Angiotensin II.
  •  Increase plasma kinin levels and potentiate the hypotensive action of bradykinin. 
  • Elevated kinins and prostaglandins may be responsible for cough induced by ACE inhibitors.
  • Interferes with degradation of substance P.
  • The lowering of blood pressure depends on sodium ion status and renin angiotensin activity.
  • The hypotension is due to decrease of total peripheral resistance.
  • Both systolic and diastolic blood pressure falls
  • Renal, cerebral and coronary blood flow is not compromised
  • 70% of orally administered drug is absorbed.
  • Food reduces the bioavailability
  • Partly metabolized and excreted unchanged in urine.
  • Poorly crosses blood brain barrier.

Adverse Effects

  • Usually well tolerated
  • Occasionally hypotension,hyperkalaemia,cough,allergy,angiodema,dysguesia,foetal abnormalities, nausea, bowel upset, granulocytopenia,proteinuria, acute renal failure may occur.

Drug interactions

  • NSAIDs attenuate hypotensive action
  • Antacids reduce bioavailability

Enalapril

  • Prodrug converted to enalaprilat - tripeptide analogue.
  • Poorly absorbed.

Advantages

  • More potent than captopril.
  • Food does not affect absorption.
  • Onset of action is slower.
  • Longer duration of action
  • Adverse effects is minimal.

Lisinopril

  • Lysine derivative of enalaprilat.
  • Absorbed orally slowly
  • Food does not interfere with its absorption
  • Duration of action is longer permitting single daily dosing
  • Uniform hypotensive action.
  • Minimal side effects with reduction in venous return, cardiac contractility and cardiac output.

Perindopril

  • Long acting ACE inhibitor.
  • Slow onset of action.
  • Undergoes extensive metabolism.
  • Tends to restore the reduced elastic properties of arteries and heart in hypertensive.

Ramipril

  • Long acting ACE inhibitor
  • Extensive tissue distribution. 
Last modified: Tuesday, 15 May 2012, 10:40 AM