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Spironolactone

(spir on'' oh lak' tone)

PCaution when used during lactation : Caution when used during pregnancy

Molecule Info

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WARNING

Spironolactone has been shown to be a tumorigen in chronic toxicity studies in rats. Spironolactone should be used only in those conditions where this is clearly indicated. Unnecessary use of this drug should be avoided. 

ATC Classification C03DA01 - Spironolactone; Belongs to the class of potassium-sparing agents, aldosterone antagonists. Used as diuretics.
Description

Spironolactone tablets USP, for oral administration contain 25 mg, 50 mg, or 100 mg of the aldosterone antagonist spironolactone, 17-hydroxy-7α - mercapto-3-oxo-17α -pregn-4-ene-21-carboxylic acid (-lactone acetate. The molecular formula is C24H3204S.

Spironolactone is practically insoluble in water, soluble in alcohol, and freely soluble in benzene and in chloroform. Inactive ingredients include calcium sulfate, corn starch, crospovidone, dextrose, hypromellose, magnesium stearate, maltodextrin, natural peppermint flavor, polydextrose, polyethylene glycol, povidone, silicon dioxide, titanium dioxide, triacetin.

Indication(s)

Spironolactone,the potassium-sparing diuretic is indicated in-

  • Congestive heart failure
  • Nephrotic syndrome
  • Hepatic cirrhosis with ascites and oedema
  • Malignant ascites
  • The diagnosis and treatment of primary aldosteronism.
Dosage & Administration

Spironolactone tablets, to be taken orally, should always be administered with fluid and preferably with food to aid absorption.

Adults:

Congestive heart failure: Usually 100mg daily. In difficult or severe cases the dosage may be gradually increased up to 400mg daily. When oedema is controlled, the usual maintenance level is 25 – 200mg daily.

Nephrotic syndrome: Usually 100-200mg daily. Spironolactone has not been shown to be anti-inflammatory, nor to affect the basic pathological process. Its use is only advised if glucocorticoids by themselves are insufficiently effective.

Hepatic cirrhosis with ascites and oedema: If urinary Na+/K+ ratio is greater than 1.0; 100mg daily. If the ratio is less than 1.0; 200-400mg daily. Maintenance doses should be individually determined.

Malignant ascites: Initial dosage is usually 100-200mg daily. In severe cases the dosage may be gradually increased up to 400mg daily. When oedema is controlled, dosage should be individually determined.

Diagnosis and treatment of primary aldosteronism: Spironolactone may be employed as an initial diagnostic measure to provide presumptive evidence of primary hyperaldosteronism while patients are on normal diets.

Long test: Spironolactone is administered at a daily dosage of 400mg for 3-4 weeks. Correction of hypokalaemia and of hypertension provides presumptive evidence for the diagnosis of primary hyperaldosteronism.

Short test: Spironolactone is administered at a daily dosage of 400mg for 4 days. If serum potassium increases during spironolactone administration but drops when spironolactone is discontinued, a presumptive diagnosis of primary hyperaldosteronism should be considered.

After the diagnosis of hyperaldosteronism has been established by more definitive testing procedures, spironolactone may be administered in doses of 100-400mg daily in preparation for surgery. For patients who are considered unsuitable for surgery, spironolactone may be employed for long-term maintenance therapy at the lowest effective dosage determined for the individual patient.

Elderly: It is recommended that treatment should commence with the lowest dose and be titrated upwards as required in order to achieve maximum benefit. Caution should be exercised in severe hepatic and renal impairment which may alter drug metabolism and excretion.

Children: Initially daily dosage should provide 3mg of spironolactone per kg bodyweight in divided doses. Dosage should be adjusted in accordance with response and tolerance. If necessary the tablets may be crushed and taken dispersed in food or drink.

Overdosage

Toxic effects of overdosage are drowsiness, mental confusion, nausea, vomiting, dizziness or diarrhoea. Hyponatraemia or hyperkalaemia may be induced but these effects are unlikely to be associated with acute overdosage. Symptoms of hyperkalaemia may manifest as paraesthesia, lassitude and muscular weakness, flaccid paralysis or muscle spasm and may be difficult to distinguish clinically from hypokalaemia.

No specific antidote has been identified. Improvement may be expected on cessation of therapy. Electrocardiographic changes are the earliest specific signs of potassium disturbances. General supportive measures include replacement of fluids and electrolytes may be indicated. For hyperkalaemia, reduce potassium intake, administer potassium-excreting diuretics, intravenous glucose with regular insulin, or oral ion-exchange resins. 

Contraindication(s)

Spironolactone is contraindicated in the following cases:

• Anuria (patients are at greater risk of developing hyperkalaemia);

• Active renal insufficiency, rapidly progressing or severe impairment of renal function (spironolactone may aggravate electrolyte imbalance and the risk of developing hyperkalaemia is increased);

• Hyperkalaemia (spironolactone may further increase serum potassium concentrations);

• Addison's disease;

• Hypersensitivity to spironolactone or any of the ingredients in the product;

• Diabetes mellitus, especially in patients with confirmed or suspected renal insufficiency;

• Diabetic nephropathy (increased risk of hyperkalaemia. Spironolactone should be discontinued at least 3 days prior to a glucose tolerance test because of the risk of severe hyperkalaemia).

Precaution(s)

• Patients with rare hereditary problems of galactose intolerance, the lapp lactase deficiency or glucose – galactose malabsorption should not take this medicine.

• Patients receiving spironolactone should be carefully evaluated for possible disturbances of fluid and electrolyte balance, particularly in the elderly and in those with significant renal and hepatic impairment.

• Hyperkalaemia may occur in patients with impaired renal function or excessive potassium intake and can cause cardiac irregularities which may be fatal. Should hyperkalaemia develop, spironolactone should be discontinued, and if necessary, active measures taken to reduce the serum potassium to normal. Dilutional hyponatraemia may be induced especially when spironolactone is concurrently administered with other diuretics.

• Care should be taken in patients suffering from hyponatraemia.

• Reversible increases in blood urea have been reported with spironolactone therapy, particularly in the presence of impaired renal function.

• Reversible hyperchloraemic metabolic acidosis, usually in association with hyperkalaemia, has been reported to occur in some patients with decompensated hepatic cirrhosis, even in the presence of normal renal function.

• Caution is required in severely ill patients and those with relatively small urine volumes who are at greater risk of developing hyperkalaemia.

• Caution is required in patients with a predisposition to metabolic or respiratory acidosis. Acidosis potentiates the hyperkalaemic effects of spironolactone and spironolactone may potentiate acidosis.

• Spironolactone has been shown to produce tumours in rats when administered at high doses over a long period of time. The significance of these findings with respect to clinical use is not certain. However, the long-term use of spironolactone in young patients requires careful consideration of the benefits and the potential hazard involved.

• Caution should be exercised in patients diagnosed with porphyria as spironolactone is considered unsafe in these patients.

• Care should be taken in patients suffering from menstrual abnormalities or breast enlargement.

 
Adverse Drug Reaction(s)

• Blood and lymphatic system disorders: agranulocytosis, eosinophilia and thrombocytopenia have been reported rarely. Spironolactone may cause transient elevations in blood urea nitrogen (BUN) especially in patients with renal impairment. Hyponatraemia has been reported rarely.

• Hypersensitivity: these occur rarely and are usually mild but very occasionally may be severe causing swelling, shock and collapse. Shortness of breath, skin rash or itching has been reported rarely.

• Metabolism and nutrition disorders: hyperkalemia and hyponatraemia has been reported rarely. Electrolyte disturbances.

• Nervous system disorders: ataxia, drowsiness, dizziness, headache and clumsiness have been reported although these are less common.

• Psychiatric disorders: lethargy.

• Cardiac disorders: severe hyperkalaemia may result in paralysis, flaccid paraplegia and cardiac arrhythmias with subsequent cardiovascular collapse. This can be fatal in patients with impaired renal function.

• Hepato – biliary disorders: hepatotoxicity has been reported.

• Gastrointestinal disorders: gastritis, gastric bleeding, stomach cramps, diarrhoea, vomiting and ulceration are more frequent effects.

• Skin and subcutaneous tissue disorders: urticaria and alopecia has been reported rarely. Skin rashes have also been reported.

• Musculoskeletal, connective tissue and bone disorders: osteomalacia.

• Renal and urinary disorders: acute renal failure, particularly in those with pre-existing renal impairment.

• Reproductive system and breast disorders: gynaecomastia may develop in association with the use of spironolactone. Development appears to be related to both dosage level and duration of therapy and is usually reversible once therapy is discontinued. In rare instances some breast enlargement may persist. Alteration in voice pitch may also occur on rare occasions which may not be reversible. Impotence and decreased sexual ability has been reported. This is usually reversible on discontinuation of spironolactone. Breast tenderness and increased hair growth in females, irregular menstrual periods and sweating have been reported.

Drug Interaction(s)

• ACE inhibitors - since ACE inhibitors decrease aldosterone production they should not routinely be used with spironolactone, particularly in patients with marked renal impairment.

• Angiotensin-II receptor antagonists - concurrent administration of angiotensin-II receptor antagonists, e.g. valsartan, losartan, and spironolactone may result in an increase in serum potassium levels. If concurrent use is necessary, monitor serum potassium levels.

• Antihypertensives - potentiation of the effect of antihypertensive drugs occurs and their dosage may need to be reduced when spironolactone is added to the treatment regime, and then adjusted as necessary.

• Anti-diabetics – administration with chlorpropamide may increase risk of hyponatraemia.

• Aspirin – may reduce the diuretic effect of spironolactone.

• Cardiac glycosides - spironolactone has been reported to increase serum digoxin concentration and to interfere with certain serum digoxin assays. In patients receiving digoxin and spironolactone, the digoxin response should be monitored by means other than serum digoxin concentrations, unless the digoxin assay used has been proven not be affected by spironolactone therapy. If it proves necessary to adjust the dose of digoxin, patients should be carefully monitored for evidence of enhanced or reduced digoxin effect.

• Ciclosporin - Co-administration of potassium-sparing diuretics with ciclosporin may result in hyperkalaemia. Avoid concurrent use of spironolactone and ciclosporin. If concurrent therapy is necessary, monitor serum potassium levels for persistent elevations in patients.

• Corticosteroids - co-administration of spironolactone with fludrocortisone may result in a paradoxical dose-related increase in urinary potassium excretion. If concomitant administration is necessary, closely monitor serum potassium levels.

• Coumarins - in patients receiving oral anticoagulant therapy with warfarin, the prothrombin time ratio or INR (international normalised ratio) should be monitored with the addition and withdrawal of treatment with spironolactone, and should be reassessed periodically during concurrent therapy. Adjustments of the warfarin dose may be necessary in order to maintain the desired level of anticoagulation.

• Diuretics - spironolactone should not be administered concurrently with other potassium-sparing diuretics as this may induce hyperkalaemia. Potassium canrenoate, a metabolite of spironolactone, has been shown to cause myeloid leukaemia in rats.

• Lithium - concurrent use of lithium and spironolactone may result in increased lithium concentrations and lithium toxicity (weakness, tremor, excessive thirst, and confusion) due to decreased lithium excretion. If concomitant therapy is necessary monitor serum lithium levels within the first five to seven days of adding or discontinuing spironolactone and periodically thereafter. Lower lithium doses may be required with concomitant spironolactone therapy.

• NSAIDs may attenuate the natriuretic efficacy of diuretics due to inhibition of intrarenal synthesis of prostaglandins. There may be an increased risk of nephrotoxicity and hyperkalaemia when NSAIDs, notably indometacin are used with spironolactone. Indometacin and mefenamic acid, inhbit the excretion of canrenone reducing the diuretic effect.

• Potassium salts – potassium supplements are contraindicated except in cases of initial potassium depletion. If potassium supplementation is considered essential, serum electrolytes should be monitored.

• Sympathomimetics - spironolactone reduces vascular responsiveness to noradrenaline (norepinephrine); caution should be exercised in the management of patients subjected to regional or general anaesthesia.

• Tacrolimus - spironolactone should not be used in patients undergoing therapy with tacrolimus as concomitant use has resulted in mild to severe hyperkalaemia.

• Ulcer healing drugs - as carbenoxolone may cause sodium retention and thus decrease the effectiveness of spironolactone, concurrent use of the two agents should be avoided.

• In fluorimetric assays spironolactone may interfere with the estimation of compounds with similar fluorescence characteristics.

• Liver function tests – spironolactone may enhance the metabolism of antipyrine used in liver function tests.

Pregnancy Category (FDA) and use in Specific Population

Spironolactone or its metabolites may cross the placental barrier. With spironolactone feminisation has been observed in male rat foetuses. Spironolactone should be used with caution in pregnant women, weighing the potential risk to the mother and foetus against the possible benefits. Canrenone, a metabolite of spironolactone, appears in breast milk, therefore an alternative method of infant feeding should be instituted.

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Category D: if used in gestational HTN. There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Pharmacology

Pharmacodynamics

Spironolactone is a steroid with a structure resembling that of the natural adrenocorticoid hormone, aldosterone. It acts as a competitive inhibitor of aldosterone and acts on the distal portion of the renal tubule thereby increasing sodium and water excretion and reducing potassium excretion. It is classed as a potassium sparing diuretic or aldosterone antagonist.

Pharmacokinetics

 

Absorption - Spironolactone is incompletely but fairly rapidly absorbed from the gastrointestinal tract and the extent of absorption will depend on the particle size and formulation and is improved after food. Bioavailability is estimated from 60 to 90%. Time to peak plasma concentration is approximately one hour.

 

Distribution â€“ Although the plasma half life of spironolactone itself is short (1.3 hours) the half lives of the active metabolites are longer (ranging from 2.8 to 11.2 hours). Spironolactone is estimated to be 90% protein bound. Volume of distribution, extent of tissue accumulation and ability to cross the blood brain barrier are not known. Spironolactone or its metabolites may cross the placental barrier and canrenone is secreted in breast milk. Spironolactone is known to have a slow onset of action two to three days and a slow diminishment of action.

 

Metabolism â€“ The main site of biotransformation is the liver where it is metabolised, to 80% sulphur containing metabolites such as 7 alpha-thiomethylspironolactone and canrenone (20%). Many of these metabolities also have a diuretic-activity. Canrenone, which is an active metabolite, has a biphasic plasma half life of about 4 – 17 hours.

 

Elimination â€“ Spironolactone is excreted in the urine and faeces in the form of metabolites.

 

The renal action of a single dose of spironolactone reaches its peak after 7 hours, and activity persists for at least 24 hours.

Storage
Store <25°C.

Brand/Product Info


Total Products : 6      
Brand Name Manufacturer/Marketer Composition Dosage Form Pack Size & Price
Inospiron 25 Incepta Pharmaceuticals Limited Spironolactone BP 25 mg Tablet 10x10's:MRP 500 Tk
RESITONE Beximco Pharmaceuticals Ltd Spironolactone BP 50mg +Furosemide BP 20mg Tablet 30's: 180.60 MRP
RESITONE PLUS Beximco Pharmaceuticals Ltd Spironolactone BP 50mg +Furosemide BP 40mg Tablet 30's: 240.90 MRP
SPIRETIC Drug International Ltd Spironolactone USP 25mg Tablet 25mg x 30's: 150.00 MRP
SPIROCARD Popular Pharmaceuticals Ltd. Spironolactone USP 25mg & 100mg Tablet 25mg x 100's,100mg x 30's: 502.00 & 542.10 MRP
VEROSPIRON Ambee Pharmaceuticals Ltd. Spironolactone USP 25mg Tablet 100's: 201.00 MRP
 See Brand Manufacturer's Prescribing Information |  Back to top |
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