Spironolactone

What it is and how it works

Mechanism of Action Spironolactone is a specific pharmacologic antagonist of aldosterone, acting primarily 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 is retained. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism. It may be given alone or with other diuretic agents that act more proximally in the renal tubule.

Mechanism class: Aldosterone Antagonists

Indications

INDICATIONS AND USAGE Spironolactone tablets are indicated in the management of: Primary Hyperaldosteronism for Establishing the diagnosis of primary hyperaldosteronism by therapeutic trial. Short-term preoperative treatment of patients with primary hyperaldosteronism. Long-term maintenance therapy for patients with discrete aldosterone-producing adrenal adenomas who are judged to be poor operative risks or who decline surgery. Long-term maintenance therapy for patients with bilateral micro- or macronodular adrenal hyperplasia (idiopathic hyperaldosteronism). Edematous Conditions for Patients with Congestive Heart Failure For the management of edema and sodium retention when the patient is only partially responsive to, or is intolerant of, other therapeutic measures. Spironolactone tablets are also indicated for patients with congestive heart failure taking digitalis when other therapies are considered inappropriate. Cirrhosis of the Liver Accompanied by Edema and/or Ascites Aldosterone levels may be exceptionally high in this condition.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION Primary Hyperaldosteronism Spironolactone tablets may be employed as an initial diagnostic measure to provide presumptive evidence of primary hyperaldosteronism while patients are on normal diets. Long Test Spironolactone tablets are administered at a daily dosage of 400 mg for 3 to 4 weeks. Correction of hypokalemia and of hypertension provides presumptive evidence for the diagnosis of primary hyperaldosteronism. Short Test Spironolactone tablets are administered at a daily dosage of 400 mg for 4 days.

Contraindications

CONTRAINDICATIONS Spironolactone tablets are contraindicated for patients with anuria, acute renal insufficiency, significant impairment of renal excretory function, hyperkalemia, Addison’s disease, and with concomitant use of eplerenone.

Warnings and precautions

WARNINGS Potassium Supplementation Potassium supplementation, either in the form of medication or as a diet rich in potassium, should not ordinarily be given in association with spironolactone therapy. Excessive potassium intake may cause hyperkalemia in patients receiving spironolactone (see PRECAUTIONS: General ).

Storage and supply

HOW SUPPLIED Spironolactone Tablets, USP are available containing 25 mg, 50 mg or 100 mg of spironolactone, USP. The 25 mg tablet is a white film-coated, round, unscored tablet debossed with M over 146 on one side of the tablet and blank on the other side.

Source: Spironolactone (Spironolactone) — US FDA prescribing information, 2021-10-14, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.