Medications and Drugs

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Medical Author: Omudhome Ogbru, Pharm.D.
Medical Editor: Jay Marks, M.D.

GENERIC NAME: spironolactone

BRAND NAME: Aldactone

DRUG CLASS AND MECHANISM: One of the main functions of the kidneys is to retain salt (sodium chloride) and water in the body. In patients with heart failure and cirrhosis, increased levels of a hormone produced by the adrenal glands, called aldosterone, causes salt and fluid to be retained by the kidneys. (At the same time, it also causes the kidneys to eliminate potassium.) The body becomes overloaded with salt and water, and this worsens the heart failure. Spironolactone inhibits the action of aldosterone thereby causing the kidneys to excrete salt and fluid in the urine while retaining potassium. Therefore, spironolactone is classified as a potassium-sparing diuretic, a drug that promotes the output of urine (diuretic) while allowing the kidneys to hold onto potassium. The FDA approved spironolactone in October 1985.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets 25, 50, and 100 mg

STORAGE: Spironolactone should be stored at room temperature, below 25 C (77 F).

PRESCRIBED FOR: Spironolactone removes excess fluid from the body in congestive heart failure, cirrhosis of the liver, and kidney disease. It can also be used in combination with other drugs to treat elevated blood pressure and for treating diuretic-induced low potassium (hypokalemia). Spironolactone also is used to counteract the effects of excessive adrenal aldosterone production (hyperaldosteronism). Aldosterone overproduction can occur from a tumor in the adrenal gland or enlarged adrenal glands (hyperplasia of the adrenal glands).

DOSING: Spironolactone may be taken with or without food. The dosage range is 25-400 mg daily in single or divided doses.

DRUG INTERACTIONS: Spironolactone can lower blood sodium levels while raising blood potassium levels. Excessively high blood potassium levels can lead to potentially life-threatening abnormalities in the rhythm of the heart. Therefore, spironolactone usually is not administered with other agents that can raise blood potassium levels, such as potassium supplements, angiotensin converting enzyme (ACE) inhibitors [for example, enalapril (Vasotec)], indomethacin (Indocin), or other potassium-sparing diuretics. Spironolactone can cause elevation of blood digoxin (Lanoxin) to toxic levels, requiring adjustment of the digoxin dosage.

PREGNANCY: There are no adequate studies in pregnant women. Spironolactone may be harmful if used for treating gestational hypertension (high blood pressure during pregnancy).

NURSING MOTHERS: An active metabolite of spironolactone is secreted in breast-milk. To avoid adverse effects in the newborn, mothers should avoid breastfeeding while taking spironolactone.

SIDE EFFECTS: Side effects of spironolactone include headache, diarrhea, cramps, drowsiness, rash, nausea, vomiting, impotence, irregular menstrual periods, and irregular hair growth. Fluid and electrolytes imbalance (for example, low sodium, low magnesium, and high potassium) may occur, so patients should be monitored carefully. Enlargement of the breasts (gynecomastia) may also occur and is related to dose and duration of therapy. It usually reverses upon discontinuation of spironolactone.

Reference: FDA Prescribing Information