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Spironolactone
Aka: Spironolactone, Aldactone
- Mechanism
- Potassium-Sparing Diuretic via Aldosterone blockade
- Spironolactone is a Aldosterone competitive inhibitor
- Acts at distal convoluted renal tubule
- Congestive Heart Failure
- Works synergistically with ACE Inhibitors in CHF
- ACE Inhibitors block Angiotensin II production
- Renal response is to increase Aldosterone
- Spironolactone blocks Aldosterone escape
- Indications
- Left-sided Congestive Heart Failure
- First line agent for NYHA Class III or IV Heart Failure, in conjunction with ACE Inhibitor and Beta Blocker
- Monitor for Hyperkalemia (esp. with ACE Inhibitor) and renal dysfunction
- May use Eplerenone as an alternative (but more expensive)
- Edematous States
- Cirrhosis
- Primary Hyperaldosteronism
- Nephrotic Syndrome
- Hyperandrogenism in women
- Hirsutism
- Polycystic Ovary Disease
- Refractory Hypertension
- See Hypertension Combination Therapy
- Contraindications
- Anuria
- Renal Insufficiency with Serum Creatinine over 2.4 mg/dl (GFR <30 ml/minute/1.73m2)
- Hyperkalemia (Serum Potassium >5 meq/L)
-
Drug Interactions
- Increased Serum Potassium (Hyperkalemia risk)
- Potassium Supplementation
- NSAIDs
- ACE Inhibitor
- Trimethoprim-Sulfamethoxazole
- Salicylates
- Decrease Spironolactone effect
- Digoxin
- Increased Digoxin Toxicity risk via increased Digoxin half life
- Norepinephrine
- Decreases NorepinephrineVasopressor activity
- Dosing
- Congestive Heart Failure
- Start 12.5 mg orally daily
- May increase to 25 mg orally daily after 4 weeks (up to 50 mg, but increased risk of Hyperkalemia)
- Monitor Serum Potassium at 3 days, 7 days and then monthly for the first 3 months
- Diuretic
- Dose: 50-100 mg orally per day divided once to twice daily
- Hyperandrogenism
- Dose: 50 mg orally twice daily
- Hypertension
- Dose: 12.5 to 50 mg orally daily
- Monitoring
- Serum Potassium
- Renal Function (Serum Creatinine)
- Pharmacokinetics
- Liver metabolism to active metabolite (canrenone)
- Primarily renal excretion
- Half-life: 14 to 16 hours (up to 24-36 hours)
- Adverse Effects
- Gynecomastia (in men)
- Hyperkalemia
- Avoid excessive Dietary Potassium
- References
- (2017) Presc Lett 24(12): 69
- Margo (2001) Am Fam Physician 64(8):1393-8 [PubMed]
- Pitt (1999) N Engl J Med 341:709-17 [PubMed]