Visual Summary

RAAS Blockers in Heart Failure

Module 2 — Introduction to Medical Pharmacology

Three Drug Classes Compared

Class 1

ACE Inhibitor

  • Blocks angiotensin-converting enzyme
  • Raises bradykinin
  • Causes cough, rare angioedema

Class 2

Angiotensin Receptor Blocker

  • Blocks the angiotensin II receptor
  • No bradykinin elevation
  • No cough, lower angioedema risk

Class 3

Sacubitril/Valsartan

  • Neprilysin inhibitor plus angiotensin receptor blocker
  • Preferred when tolerated
  • Never combine with an ACE inhibitor or ARB

Why Sacubitril/Valsartan Needs Both Components

Sacubitril Alone

Blocks neprilysin, but neprilysin also breaks down angiotensin II

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Problem

Angiotensin II would rise unopposed

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Solution

Valsartan blocks the angiotensin II receptor directly

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Result

Natriuretic peptides amplified, angiotensin II blocked

Shared Contraindications

ContraindicationApplies To
PregnancyAll three classes
Bilateral renal artery stenosisAll three classes
Prior angioedema with an ACE inhibitorACE inhibitors and sacubitril/valsartan
Concurrent ACE inhibitor or ARBNever combine with sacubitril/valsartan
Hyperkalemia risk shared by all three Hydralazine/isosorbide dinitrate when RAAS blockade is not possible