Spironolactone; Uses, Dosage, Side Effects, Drug Interactions


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Spironolactone is a potassium-sparing diuretic that acts by antagonism of aldosterone in the distal renal tubules. It is used mainly in the treatment of refractory edema in patients with congestive heart failure, nephrotic syndrome, or hepatic cirrhosis. Its effects on the endocrine system are utilized in the treatments of hirsutism and acne but they can lead to adverse effects.

Spironolactone is a synthetic 17-spironolactone corticosteroid with a potassium-sparing diuretic, antihypertensive, and antiandrogen activities. Spironolactone competitively inhibits adrenocortical hormone aldosterone activity in the distal renal tubules, myocardium, and vasculature. This agent may inhibit the pathophysiologic effects of aldosterone produced in excess by various types of malignant and benign tumors.

Spironolactone is a medication that is primarily used to treat fluid build-up due to heart failure, liver scarring, or kidney disease.It is used mainly in the treatment of refractory edema in patients with congestive heart failure, nephrotic syndrome, or hepatic cirrhosis. It is also used in the treatment of high blood pressure, low blood potassium that does not improve with supplementation, early puberty in boys, acne and excessive hair growth in women, and as a part of feminizing hormone therapy in transgender women. Spironolactone is taken by mouth.

Mechanism of Action of Spironolactone

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 which act more proximally in the renal tubule. Aldosterone interacts with a cytoplasmic mineralocorticoid receptor to enhance the expression of the Na+, K+-ATPase and the Na+ channel involved in a Na+ K+ transport in the distal tubule. Spironolactone bind to this mineralocorticoid receptor, blocking the actions of aldosterone on gene expression. Aldosterone is a hormone; its primary function is to retain sodium and excrete potassium in the kidneys.

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Spironolactone exhibits antiandrogenic effects in males and females. The mechanism of antiandrogenic activity of spironolactone is complex and appears to involve several effects of the drug. Spironolactone decreases testosterone biosynthesis by inhibiting steroid 17alpha-monooxygenase (17alpha-hydroxylase) activity, possibly secondary to destruction of microsomal cytochrome P-450 in tissues with high steroid 17alpha-monooxygenase activity (e.g., testes, adrenals). The drug also appears to competitively inhibit binding of dihydrotestosterone to its cytoplasmic receptor protein, thus decreasing androgenic actions at target tissues. Spironolactone-induced increases in serum estradiol concentration also may contribute to its antiandrogenic activity, although such increases may not occur consistently; such increases appear to result from the increased conversion of testosterone to estradiol. Spironolactone may have variable effects on serum 17-hydroxyprogesterone concentrations, possibly decreasing its production by inhibiting steroid 17alpha-monooxygenase activity or decreasing its conversion (with resultant accumulation) to androstenedione by inhibiting cytochrome P450-dependent 17alpha-hydroxyprogesterone aldolase (17,20-desmolase) activity. Serum progesterone concentrations may increase with the drug secondary to decreased hydroxylation (via steroid 17alpha-monooxygenase) to 17-hydroxyprogesterone. In children, compensatory increases in lutropin (luteinizing hormone, LH) and follicle-stimulating hormone (FSH) secretion can occur, probably secondary to the drug’s antiandrogenic effects (i.e., a feedback response to decreasing serum testosterone concentrations and/or peripheral androgenic activity).

Indications of Spironolactone

  • Acne
  • Ascites
  • Congestive heart failure
  • Edema
  • Gender dysphoria
  • Alopecia
  • Heart failure
  • High blood pressure
  • Hypokalemia
  • Primary hyperaldosteronism
  • Primary hyperaldosteronism diagnosis
  • Glomerulonephritis minimal lesion
  • High Blood Pressure (Hypertension)
  • Primary hyperaldosteronism
  • Chronic heart failure with reduced ejection fraction (NYHA Class III)
  • Chronic heart failure with reduced ejection fraction (NYHA Class IV)
  • Idiopathic hyperaldosteronism.
  • Used primarily to treat low-renin hypertension, hypokalemia, and Conn’s syndrome.
  • For use in combination with standard therapy (including diuretic support, where necessary) for the treatment of congestive heart failure caused by valvular regurgitation in dogs.

Contra-Indications of Spironolactone

  • Addison’s disease
  • Low amount of sodium in the blood
  • The high amount of potassium in the blood
  • Acute renal Failure
  • Kidney disease with a reduction in kidney function
  • Severe renal impairment
  • Decreased blood volume
  • The absence of urine formation
  • Hyperchloremic acidosis
  • Acid base problem with low chloride and basic pH blood

Dosages of Spironolactone

  • Strengths: 25 mg;  50 mg;100 mg; 25 mg/5 mL


  • 25 to 200 mg orally per day in single or divided doses
  • Duration of therapy: When given as the sole diuretic, continue the initial dose for at least 5 days, after which the initial dose may be adjusted to an optimal maintenance dose.
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  • Initial dose: 50 to 100 mg orally per day in single or divided doses
  • Duration of therapy: Treatment should be continued for at least 2 weeks to achieve a maximum response. Subsequently, the dose may be adjusted according to patient response.

Congestive Heart Failure

  • Initial dose: 25 mg orally once a day assuming serum potassium is less than or equal to 5 mEq/L and serum creatinine is less than or equal to 2.5 mg/dL

Maintenance Dose

  • Patients tolerant of initial dose: May increase to 50 mg orally once a day as clinically indicated
  • Patients intolerant of initial dose: May decrease to 25 mg orally every other day


  • 25 to 100 mg orally per day


  • 25 to 200 mg orally per day in single or divided doses
  • Duration of therapy: When given as the sole diuretic, continue the initial dose for at least 5 days, after which the initial dose may be adjusted to an optimal maintenance dose.

Side Effects of Spironolactone

Most common

More common

Less common

Drug Interactions of Spironolactone

Spironolactone may interact with following drugs, supplements & may change the efficacy of the drug

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Pregnancy & Lactation of Spironolactone

FDA Pregnancy Category C


Spironolactone crosses the placenta and may affect the developing baby if taken by a woman when she is pregnant. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication to talk to your doctor about the potential benefits and risks of taking this medication during pregnancy.


This medication passes into breast milk. If you are a breastfeeding mother and are taking spironolactone, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding.




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