the antifibrotic
A mineralocorticoid receptor antagonist (MRA) that prevents the downstream effects of aldosterone: sodium retention, potassium wasting, and crucially, cardiac fibrosis.
- Mechanism: Competitive antagonist at the mineralocorticoid receptor in the distal tubule/collecting duct.
- Dosing: HF: 12.5–25 mg daily (Target 50 mg rarely needed). Ascites: 100–400 mg daily (High dose needed to overcome secondary hyperaldosteronism).
- PK: Metabolized to active metabolite (canrenone). Long half-life.
indications
- HFrEF: Mortality benefit (RALES).
- HFpEF: Reduced hospitalizations (TOPCAT - regional variation).
- Cirrhosis: First-line diuretic for ascites.
- Primary Aldosteronism (Conn’s): Medical management.
adverse effects
- Hyperkalemia: Major dose-limiting toxicity. Monitor closely.
- Gynecomastia / Breast Pain: Anti-androgenic effect. (Switch to Eplerenone if occurs).
- AKI: Careful in pre-existing CKD.