Spironolactone: 6 things you should know
Medically reviewed by C. Fookes, BPharm. Last updated on Sep 10, 2018.
1. How it works
- Spironolactone is a medicine used in a variety of heart-related and fluid-retaining conditions. It is also used for the diagnosis and management of primary hyperaldosteronism (a condition where the adrenal glands produce too much of the hormone aldosterone leading to low potassium levels and a more alkaline blood pH).
- Spironolactone inhibits the action of aldosterone by binding to specific receptors in the kidney where aldosterone controls the balance of salt and water in the body. Blocking aldosterone increases the excretion of sodium and other salts through the kidney into the urine. As these salts leave the body, water is also drawn alongside. Through this mechanism, spironolactone removes excess fluid from the body and also has a blood pressure lowering effect.
- Spironolactone belongs to the class of medicines called aldosterone receptor antagonists. Spironolactone may also be called a potassium-sparing diuretic.
- Removes excess fluid from the body and may be used in the treatment of heart failure, cirrhosis of the liver, and in nephrotic syndrome (a type of kidney disease). Has been shown to increase survival and reduce the need for hospitalization in people with severe heart failure.
- May be used in the treatment of high blood pressure (hypertension) in conjunction with other medications and lifestyle measures (such as lipid control, diabetes management, smoking cessation, blood thinning medications, exercise and a reduction in sodium intake). Reducing blood pressure is associated with an improvement in survival in people with cardiovascular disease.
- May be used in the diagnosis or treatment of primary hyperaldosteronism (a hormonal disorder characterized by over-production of aldosterone that leads to high blood pressure).
- May be used long-term in some people with inoperable aldosterone-producing tumors.
- May occasionally be used to treat hypokalemia (low potassium levels) when other treatments are inappropriate or ineffective.
- Spironolactone does not cause potassium loss nor is it likely to precipitate gout, unlike several other diuretics.
- Generic spironolactone is available.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Gynecomastia (enlargement of a man's breasts) is reported by approximately 13% of men who take spironolactone. The risk is higher with higher dosages of spironolactone and a longer duration of therapy. The gynecomastia usually reverses once spironolactone is discontinued.
- May cause low sodium levels (hyponatremia), low magnesium levels (hypomagnesia), lowered testosterone levels and high potassium levels (hyperkalemia). Low calcium levels and high blood sugar levels may also occur. Nausea, vomiting, tiredness, changes in menstruation, libido, hair-loss, and postmenopausal bleeding may also occur.
- Rarely, may cause drowsiness or dizziness and affect a person's ability to drive or operate machinery.
- May interact with a number of other drugs including those that also retain potassium (such as ACE inhibitors), lithium, NSAIDs, and digoxin.
- Not suitable for people with certain kidney problems, Addison's disease, or high potassium levels. Should be used with caution in people with other electrolyte disturbances, and in women who are pregnant or breastfeeding. Animal studies have shown that use of spironolactone is associated with a higher risk of cancer of the endocrine organs (such as the thyroid) and liver. People with diabetes may need their blood sugar levels monitored more frequently.
Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.
- May be taken with or without food. Take with food if stomach upset occurs.
- Tell your doctor if you experience any intolerable side effects, such as excessive thirst, drowsiness, muscle pains or cramps, and in men, enlarged breasts.
- Avoid taking salt substitutes that contain potassium or potassium supplements while taking spironolactone. Try to avoid foods high in potassium (such as avocados, bananas, coconut water, spinach, and sweet potato) because eating these foods may lead to potentially fatal hyperkalemia (high blood potassium levels).
- Do not drive or operate machinery if spironolactone makes you drowsy or impairs your judgment.
- Spironolactone is metabolized into sulfur-containing compounds so tell your doctor if you have a sulfa allergy before taking spironolactone.
- Your doctor may need to periodically monitor electrolyte levels in your blood while you are taking spironolactone.
6. Response and Effectiveness
- Spironolactone is metabolized into active sulfur-containing substances, and peak concentrations are reached within three to five hours. The effects of one dose of spironolactone usually last for 24 hours.
Spironolactone [Package Insert]. Revised 08/2017. CMP Pharma, Inc. https://www.drugs.com/pro/spironolactone.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use spironolactone only for the indication prescribed.
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