What it's for (Indications)
- Spironolactone is indicated for the treatment of oedema (swelling) associated with congestive heart failure, hepatic ascites (fluid in abdomen due to liver disorder), and kidney disease, particularly where potassium retention is desired.
- It is also used for the diagnosis and management of primary hyperaldosteronism.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | For primary hyperaldosteronism, spironolactone may be used as a diagnostic measure. A 'Long Test' involves administering 400 mg daily for 3 to 4 weeks. A 'Short Test' involves administering 400 mg daily for 4 days. After a definitive diagnosis of hyperaldosteronism, spironolactone may be administered in doses of 100 mg to 400 mg daily in preparation for surgery. For patients deemed unsuitable for surgery, similar daily dosages may be maintained for long-term management. |
Safety & Warnings
Common Side Effects
- Reported adverse reactions include gastrointestinal disturbances (gastric bleeding, ulceration, gastritis, diarrhea, cramping, nausea, vomiting), and reproductive system effects such as gynecomastia, inability to achieve or maintain erection, irregular menses or amenorrhea, postmenopausal bleeding, and breast pain.
- Carcinoma of the breast has been reported in some patients, though a causal relationship has not been established.
- Other side effects include hematologic abnormalities (leukopenia, agranulocytosis, thrombocytopenia), hypersensitivity reactions (fever, urticaria, maculopapular or erythematous cutaneous eruptions, anaphylactic reactions, vasculitis), metabolic imbalances (hyperkalemia, electrolyte disturbances), musculoskeletal issues (leg cramps), and nervous system/psychiatric effects (lethargy, mental confusion, ataxia, dizziness, headache, drowsiness).
- A few cases of mixed cholestatic/hepatocellular liver injury have also been reported.
Serious Warnings
- Black Box Warning: Spironolactone has been shown to be tumorigenic in chronic toxicity studies in rats. Therefore, its use should be restricted to the approved indications, and unnecessary use of this drug should be avoided.
- Patients with kidney or liver impairment should consult their doctor before taking this medicine, as close monitoring and potential dosage adjustments are necessary.
- There is a risk of hyperkalemia and other electrolyte disturbances.
- Pregnant patients should consult their doctor before use.
- Women who are breastfeeding are advised to avoid this medicine.
- Due to potential effects on alertness and motor skills, patients should avoid driving or operating machinery when taking spironolactone.
How it Works (Mechanism of Action)
Spironolactone is a specific pharmacologic antagonist of aldosterone. It acts primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. This mechanism results in increased excretion of sodium and water, while promoting potassium retention. Spironolactone functions as both a diuretic and an antihypertensive agent, and can be administered alone or in combination with other diuretics that act more proximally in the renal tubule.