For the treatment of hypertension. For the treatment of hypokalemia. For hypokalemia prevention in patients taking digoxin. For the treatment of heart failure. For the treatment of edema.
Potassium-sparing Diuretic
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 mineralcorticoid 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.
Oedema: Adult: Initially, 100 mg daily, may adjust dose according to response up to 400 mg daily. Child: Neonates: 1-2 mg/kg daily; 1 mth-12 yr: 1-3 mg/kg daily; 12-18 yr: 50- 100mg daily. To be given in 1-2 divided doses. Elderly: Initially, 25-50 mg/day in 1-2 divided doses, may increase by 25-50 mg every 5 days when necessary. Hepatic cirrhosis w/ ascites & oedema: Adult: Depending on urinary sodium/ potassium ratio: If >1: Initially, 100 mg daily & if <1: Initially, 200-400 mg daily. Child: Neonate: 1-2 mg/kg daily (Max: 7 mg/kg daily in resistant ascites); 1 mth-12 yr: 1-3 mg/kg daily (Max: 9 mg/ kg daily in resistant ascites): 12-18 yr: 50-100 mg daily (Max: 400 mg daily in resistant ascites). To be given in 2 divided doses. Elderly: Dosing adjustment may be required. Diagnosis of primary hyperaldosteronism: Adult: 400 mg daily for 3-4 wk. Correction of serum K levels & HTN gives the presumptive evidence for the diagnosis of primary aldosteronism. Elderly: Dosing adjustment may be required. Preoperative management of hyperaldosteronism: Adult: 100-400 mg daily. Long term maintenance in the absence of surgery: May initiate at 400mg daily & maintain at 100-300mg daily; lowest effective dose should be used. Elderly: Dosing adjustment may be required. Hypertension: Adult: As monotherapy: Usual dose range: 25-50 mg daily, may increase up to 100 mg daily if needed. Elderly: Initially, 25-50 mg/day in 1-2 divided doses, may increase by 25-50 mg every 5 days when necessary. Severe congestive heart failure: Adult: For patients receiving an ACE inhibitor & a loop diuretic w/ or w/o a cardiac glycoside: Initially, 12.5-25mg daily. May increase to 50 mg daily after 8 wk of treatment depending on response. Child: Neonates: 1-2 mg/kg daily; 1 mth-12 yr: 1-3 mg/kg daily; 12-18 yr: 50-100mg daily. Tobe given in 1-2 divided doses. Elderly: Dosing adjustment may be required. Diuretic-induced hypokalaemia: Adult: 25-100 mg daily. Child: Neonates: 1-2 mg/ kg daily; 1 mth-12 yr: 1-3 mg/kg daily; 12- 18 yr: 50-100 mg daily. To be given in 1-2 divided doses. Elderly: Dosing adjustment may be required. Hirsutisni: Adult: 50-200 mg daily. Elderly: Dosing adjustment may be required.
The administration of potassium supplements, a diet rich in potassium, including salt substitutes, or of other potassium sparing agents is not recommended as it may induce hyperkalemia. Severe hyperkalemia has been reported in patients co-administered potassium-sparing diuretics, including Spironolactone and ACE inhibitors. Spironolactone reduces the vascular responsiveness to noradrenaline. Therefore caution should be exercised in the management of patient subjected to regional or general anaesthesia while they are being treated with Spironolactone. Aspirin attenuates the diuretic effect of Spironolactone by blocking the secretion of
canrenone in the renal tubule. Indomethacin and Mefenamic Acid have been shown to inhibit the excretion of canrenone. As carbenoxolone may cause sodium retention and thus may decrease the effectiveness of Spironolactone, concurrent use of the two agents should be avoided. Spironolactone enhances the metabolism of antipyrine.
Anuris, hyperkalaemia, acute or progressive renal insufficiency. Addison’s disease. Patients at risk of developing hyperkalaemia & acidosis; monitor serum electrolytes; renal & hepatic impairment; DM; elderly; pregnancy.
Fluid or electrolyte imbalance, gynaecomastia, Gl upset, drowsiness, headache, hyponatraemia; tachycardia, hypotension, oliguria, hyperkalaemia; confusion, weakness, parsesthesia, hirsutism, mental disturbances, menstrual irregularities, loss of libido & impotence. Fatal hyperkalaemia in combination w/ ACE inhibitors & previous renal impairment; agranulocytosis.
Some research suggests that spironolactone has the potential to feminize male fetuses during early pregnancy and cause endocrine problems in late pregnancy by inhibiting the activity of male hormones (androgens). In general, diuretics such as spironolactone aren't recommended for pregnant women. However, only very small amounts of spironolactone and its metabolite canrenone enter breast milk, and the amount received by an infant during breastfeeding (<0.5% of the mother's dose) is considered to be insignificant. A study found that spironolactone was not associated with teratogenicity in the offspring of rats.
Acute overdosage of Spironolactone may be manifested by drowsiness, mental confusion, maculopapular or erythematous rash, nausea, vomiting, dizziness, or diarrhoea. Rarely, instances of hyponatremia, hyperkalemia, or hepatic coma may occur in patients with severe liver disease, but these are unlikely due to acute overdosage. Hyperkalemia may occur, especially in patients with impaired renal function.
Store in a cool and dry place protected from light. Keep out of reach of children.
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