Spironolactone

Mechanism :

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. Aldactone causes increased amounts of sodium and water to be excreted, while potassium is retained. Aldactone acts both as a diuretic and as an antihypertensive drug by this mechanism.

Indication :

• Diuretic
• Bronchopulmonary dysplasia
• Hyperaldosteronism test

Contraindications :

Contraindicated for patients with anuria, acute renal insufficiency, significant impairment of renal excretory function, or hyperkalemia, hyponatremia, severe renal impairment, acute renal failure, anuria, Addison’s disease, hypersensitivity to spironolactone.

Dosing :

Adverse Effect :

Gastric bleeding, ulceration, gastritis, diarrhea and cramping, nausea, vomiting, gynecomastia, inability to achieve or maintain erection, irregular menses or amenorrhea, postmenopausal bleeding, agranulocytosis, hypersensitivity reactions (fever, urticaria, maculopapular or erythematous cutaneous eruptions, anaphylactic reactions, vasculitis), mental confusion, ataxia, headache, drowsiness, lethargy, renal dysfunction.

Interaction :

ACE inhibitors: Concomitant administration of ACE inhibitors with potassium-sparing diuretics has been associated with severe hyperkalemia.
Alcohol, barbiturates, or narcotics: Potentiation of orthostatic hypotension may occur
Corticosteroids, ACTH: Intensified electrolyte depletion, particularly hypokalemia, may occur.
Pressor Amines (e.g., Norepinephrine): Spironolactone reduces the vascular responsiveness to norepinephrine.
Skeletal Muscle Relaxants, Nondepolarizing (e.g., Tubocurarine): Possible increased responsiveness to the muscle relaxant may result.
Lithium: Lithium generally should not be given with diuretics. Diuretic agents reduce the renal clearance of lithium and add a high risk of lithium toxicity.
Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): In some patients, the administration of an NSAID can reduce the diuretic, natriuretic, and antihypertensive effect of loop, potassium-sparing and thiazide diuretics.
Digoxin: Spironolactone has been shown to increase the half-life of digoxin. This may result in increased serum digoxin levels and subsequent digitalis toxicity.

Renal Dose :

Hepatic Dose :