Drugs Used in the Treatment of Heart Failure
Heart failure (HF) is a chronic condition characterized by the heart's inability to pump blood effectively, leading to fluid accumulation, reduced cardiac output, and organ hypoperfusion. Medications for heart failure aim to improve cardiac function, relieve congestion, and prolong survival.
Classification of Heart Failure Medications
- 1. ACE Inhibitors (Angiotensin-Converting Enzyme Inhibitors)
- Enalapril, Lisinopril, Ramipril
- 2. ARBs (Angiotensin II Receptor Blockers)
- Losartan, Valsartan
- 3. Diuretics
- Loop Diuretics: Furosemide
- Thiazide Diuretics: Hydrochlorothiazide
- 4. Beta-Blockers (BBs)
- Carvedilol, Bisoprolol
- 5. Aldosterone Antagonists (Potassium-Sparing Diuretics)
- Spironolactone, Eplerenone
Pharmacodynamics (Mechanism of Action)
- 1. ACE Inhibitors (ACEIs)
- Inhibit angiotensin-converting enzyme (ACE) → ↓ Angiotensin II formation.
- Vasodilation → ↓ Afterload.
- ↓ Aldosterone secretion → ↓ Sodium & water retention → ↓ Preload.
- Prevents cardiac remodeling & fibrosis.
- 2. ARBs (Angiotensin II Receptor Blockers)
- Block angiotensin II receptors (AT1 receptors) → Prevent vasoconstriction & aldosterone secretion.
- Cause vasodilation & reduce fluid retention.
- Alternative for patients intolerant to ACE inhibitors (due to cough or angioedema).
- 3. Diuretics
- Loop Diuretics (Furosemide):
- Inhibit Na⁺/K⁺/2Cl⁻ cotransporter in the loop of Henle → ↑ Sodium & water excretion.
- Reduce preload and relieve congestion.
- Thiazide Diuretics (Hydrochlorothiazide):
- Inhibit Na⁺/Cl⁻ symporter in distal convoluted tubule → Mild diuresis.
- Used in mild HF or as adjunct therapy.
- 4. Beta-Blockers (BBs)
- Block β1-adrenergic receptors → ↓ Sympathetic stimulation.
- ↓ Heart rate & myocardial oxygen demand.
- Improve left ventricular function & reduce mortality in HF.
- 5. Aldosterone Antagonists
- Inhibit aldosterone receptors → ↓ Sodium & water retention.
- Prevent myocardial fibrosis & remodeling.
- Spironolactone also has anti-androgenic effects.