Tablets: 25 mg, 50 mg, 100 mg
Edema due to congestive heart failure or nephrotic syndrome and cirrhosis of the liver accompanied by edema and/or ascites: Initially 100 mg/day with adjustments at 5-day intervals to a maintenance dose of 25-200 mg/day.
Treatment of essential hypertension: 50-100 mg/day.
Treatment of hypokalemia: 25-100 mg/day.
Diagnosis of primary hyperaldosteronism: Long test: 400 mg/day for 3-4 days. Correction of hypokalemia and hypertension concludes a positive test. Short test: 400 mg/day for 4 days. An increase in serum potassium with a subsequent decrease after the fourth day concludes a positive test.
Treatment of primary hyperaldosteronism in patients unsuitable for surgery: 100-400/day.
Pharmacology/Pharmacokinetics:
Spironolactone works by competitive antagonism of aldosterone, primarily at the aldosterone-dependent Na+/K+ exchange sites in the distal convoluted renal tubule. It reaches peak plasma levels in 3-5 hours, with a half-life of 2-16 hours. Excretion of metabolized drug occurs in the urine.
Drug Interactions:
Hyperkalemia may occur when used concomitantly with captopril and with potassium-sparing medications, including potassium supplements. Variable effects may occur when used with DIGITALIS glycosides.
Contraindications/Precautions:
Contraindicated in patients with anuria, acute renal insufficiency, significant impairment of renal function, hyperkalemia, and in patients hypersensitive to sulfonamides or spironolactone. Use with caution in patients with acute or severe hepatic failure. Patients receiving this medication should be monitored periodically for fluid and electrolyte disturbances. Use with caution in pregnant and in nursing women. Pregnancy Category B.
Adverse Effects:
Diarrhea, drowsiness, headache, amenorrhea, WEAKNESS, PARESTHESIA, MENTAL CONFUSION, DRY MOUTH, MUSCLE CRAMPS, hirsutism, urticaria, impotence, gynecomastia, nausea, and vomiting.
Timing of dosage is important because of increased diuresis. Usually given in the early morning.
May be taken with food of milk if GI upset occurs.
May cause drowsiness. Use caution while operating machinery or when mental alertness is required.
Store in a cool, dry place away from sunlight and children.
Contact a physician if the above side effects are severe or persistent.
If a dose is missed, skip it and return to normal dosing schedule.