Pharm
Spironolactone
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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 Inhibitor
s in CHF
ACE Inhibitor
s 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 State
s
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
NSAID
s
ACE Inhibitor
Trimethoprim-Sulfamethoxazole
Salicylate
s
Decrease Spironolactone effect
Digoxin
Increased
Digoxin Toxicity
risk via increased
Digoxin
half life
Norepinephrine
Decreases
Norepinephrine
Vasopressor
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]
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