| Spironolactone
Spironolactone (Aldactone)
Spironolactone
(speer-oh-no-LAK-tohn)
Pregnancy Category: D Aldactone Novo-Spiroton (Rx)
Classification: Diuretic,
potassium-sparing
See Also: See also Diuretics,
Thiazides [. ]
Action/Kinetics: Mild diuretic
that acts on the distal tubule to inhibit sodium exchange for potassium, resulting in
increased secretion of sodium and water and conservation of potassium. An aldosterone
antagonist. Manifests a slight antihypertensive effect. Interferes with synthesis of
testosterone and may increase formation of estradiol from testosterone, thus leading to
endocrine abnormalities. Onset: Urine output increases over 1-2 days. Peak: 2-3
days. Duration: 2-3 days, and declines thereafter. Metabolized to an active
metabolite (canrenone). t1/2: 13-24 hr for canrenone. Canrenone is
excreted through the urine (primary) and the bile. Almost completely bound to plasma
protein.
Uses: Primary
hyperaldosteronism, including diagnosis, short-term preoperative treatment, long-term
maintenance therapy for those who are poor surgical risks and those with bilateral
micronodular or macronodular adrenal hyperplasia. To treat edema when other approaches are
inadequate or ineffective (e.g., CHF, cirrhosis of the liver, nephrotic syndrome).
Essential hypertension (usually in combination with other drugs). Prophylaxis of
hypokalemia in clients taking digitalis. Investigational: Hirsutism, treat symptoms
of PMS, with testolactone to treat familial male precocious puberty (short-term
treatment), acne vulgaris.
Contraindications: Acute renal
insufficiency, progressive renal failure, hyperkalemia, and anuria. Clients receiving
potassium supplements, amiloride, or triamterene.
Special Concerns: Use during
pregnancy only if benefits clearly outweigh risks. Use with caution in impaired renal
function. Geriatric clients may be more sensitive to the usual adult dose.
Side Effects: Electrolyte:
Hyperkalemia, hyponatremia (characterized by lethargy, dry mouth, thirst, tiredness). GI:
Diarrhea, cramps, ulcers, gastritis, gastric bleeding, vomiting. CNS: Drowsiness,
ataxia, lethargy, mental confusion, headache. Endocrine: Gynecomastia, menstrual
irregularities, impotence, bleeding in postmenopausal women, deepening of voice,
hirsutism. Dermatologic: Maculopapular or erythematous cutaneous eruptions,
urticaria. Miscellaneous: Drug fever, breast carcinoma, gynecomastia,
hyperchloremic metabolic acidosis in hepatic cirrhosis (decompensated), agranulocytosis.
NOTE: Spironolactone has been shown to be tumorigenic in chronic rodent studies.
Laboratory Test Alterations:
Interference with radioimmunoassay for digoxin. False + plasma cortisol (as determined by
fluorometric assay of Mattingly).
Drug Interactions: - Anesthetics,
general / Additive hypotension
- ACE inhibitors / Significant hyperkalemia
- Anticoagulants,
oral / Inhibited by spironolactone
- Antihypertensives / Potentiation of
hypotensive effect of both agents. Reduce dosage, especially of ganglionic blockers, by
one-half
- Captopril / Risk of
significant hyperkalemia
- Digitalis /
Half-life of digoxin clearance. Spironolactone may inotropic effect of digoxin. Spironolactone both
and elimination t1/2 of digitoxin
- Diuretics, others / Often
administered concurrently because of potassium-sparing effect of spironolactone. Severe
hyponatremia may occur. Monitor closely
- Lithium / Chance of lithium toxicity due to renal clearance
- Norepinephrine / Responsiveness to norepinephrine
- Potassium salts / Since
spironolactone conserves potassium excessively, hyperkalemia may result. Rarely used
together
- Salicylates / Large doses may effects of spironolactone
- Triamterene / Hazardous hyperkalemia may
result from combination
How Supplied: Tablet: 25
mg, 50 mg, 100 mg
Dosage
•Tablets Edema.
Adults, initial: 100 mg/day (range: 25-200 mg/day) in two to four divided doses for
at least 5 days; maintenance: 75-400 mg/day in two to four divided doses. Pediatric:
3.3 mg/kg/day as a single dose or as two to four divided doses.
Antihypertensive.
Adults, initial: 50-100 mg/day as a single dose or as two to four divided
doses--give for at least 2 weeks; maintenance: adjust to individual response. Pediatric:
1-2 mg/kg in a single dose or in two to four divided doses.
Hypokalemia.
Adults: 25-100 mg/day as a single dose or two to four divided doses.
Diagnosis of primary hyperaldosteronism.
Adults: 400 mg/day for either 4 days (short-test) or 3-4 weeks (long-test).
Hyperaldosteronism, prior to surgery.
Adults: 100-400 mg/day in two to four doses prior to surgery.
Hyperaldosteronism, chronic-therapy.
Use lowest possible dose.
Hirsutim.
50-200 mg/day.
Symptoms of PMS.
25 mg q.i.d. beginning on day 14 of the menstrual cycle.
Familial male precocious puberty, short-term.
Spironolactone, 2 mg/kg/day, and testolactone, 20-40 mg/kg/day, for at least 6 months.
Acne vulgaris.
100 mg/day.
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