Spironolactone is a specific pharmacologic antagonist, acting primary through competitive binding of receptors at the aldosterone dependent sodium-potassium exchange site in the distal convoluted renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium and magnesium is retained.
Spironolactone is indicated in the management of oedema and ascites in cirrhosis of the liver, malignant ascites, nephrotic syndrome, congestive heart failure and primary hyperaldosteronism.
Gynaecosmastia may develop in association with the use of Spironolactone, and physicians should be alert to its possible onset. The development of gynaecosmastia appears to be related to both dosage level and duration of therapy and is normally reversible when Spironolactone is discontinued. In rare instances, some breast enlargement may persist. Other adverse reactions that have been reported in association with Spironolactone are: gastrointestinal symptoms including cramping and diarrhoea, drowsiness, lethargy, headache, maculopular or erythematous cutaneous eruptions, urticaria, mental confusion, drug fever, ataxia, impotence, irregular menses or amenorrhoea , and post-menopausal bleeding. A few cases of agranulocytosis have been reported in patients taking Spironolactone. Adverse reactions are usually reversible upon discontinuation of the drug.
All patients receiving diuretic therapy should be observe for evidence of fluid or electrolyte imbalance, eg, hypomagnesemia, hyponatremia, hypochloremic alkalosis, and hyperkalemia. serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. Warning signs or symptoms of fluid and electrolyte imbalance, irrespective of cause, include dryness of the mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pain, muscular fatigue, hypotension, oliguria, tachycardia.