SPIRACTIN

What it is

SPIRACTIN is spironolactone, available as uncoated tablets in 25 mg and 100 mg strengths.

Approved indications

— Essential hypertension. — Adjunctive therapy in malignant hypertension. — Diuretic-induced hypokalaemia when other measures are considered inappropriate or inadequate. — Prophylaxis of hypokalaemia in patients taking digitalis when other measures are considered inadequate or inappropriate. — Congestive cardiac failure. — Hepatic cirrhosis with ascites and oedema. — Nephrotic syndrome. — Diagnosis and treatment of primary hyperaldosteronism. — Hirsutism in females.

Dosing overview

For essential hypertension, the dose is 50 to 100 mg per day, which may be given either in divided doses or as a single daily dose. Dosage should be adjusted according to response, but maximum effect may not occur for up to two weeks after starting treatment. For oedematous disorders, dosing varies by condition. In congestive cardiac failure, the initial dose is 100 mg per day, which may be gradually increased up to 200 mg per day in difficult or severe cases, with a usual maintenance level of 25 to 200 mg per day once oedema is controlled. In cirrhosis, the recommended dose is 100 mg per day if the urinary sodium/potassium ratio is greater than one, or 200 to 400 mg per day if the ratio is less than one. In nephrotic syndrome, the usual dose is 100 to 200 mg per day. For female hirsutism, 100 to 200 mg per day in divided doses is usual, although 50 mg daily has also been shown to be effective, with clinical improvement typically shown within 3 to 6 months.

Key safety warnings

Concomitant use of SPIRACTIN with angiotensin converting enzyme inhibitors, non-steroidal anti-inflammatory drugs, angiotensin II antagonists, aldosterone blockers, heparin, low molecular weight heparin, other drugs or conditions known to cause hyperkalaemia or potassium supplements, a diet rich in potassium including salt substitutes containing potassium, or other potassium sparing agents is not recommended as it may lead to severe hyperkalaemia. Hyperkalaemia may be fatal in patients with severe heart failure (New York Heart Association Class III–IV). Potassium and creatinine levels should be closely monitored one week after initiation or monthly for the first 3 months, then quarterly for a year, and then every 6 months when increasing the dose of SPIRACTIN. Gynaeccomastia may develop in association with the use of SPIRACTIN, appearing to be related to both dosage level and duration of therapy and normally reversible when SPIRACTIN is discontinued. SPIRACTIN has been shown to increase the half-life of digoxin, which may result in increased serum digoxin levels and subsequent digitalis toxicity; it may be necessary to reduce the digoxin dose when SPIRACTIN is administered, and the patient should be carefully monitored.

Contraindications

SPIRACTIN is contraindicated in acute renal insufficiency, significant impairment of renal function, anuria, Addison's disease or other conditions associated with hyperkalaemia, hyperkalaemia, pregnancy, hypersensitivity to spironolactone, and concomitant use of eplerenone.

PBS listing

SPIRACTIN 25 mg tablets are listed on the PBS with 2 items; restriction is unrestricted and restricted, with an ex-manufacturer price of A$7.82. SPIRACTIN 100 mg tablets are listed on the PBS with 2 items; restriction is unrestricted and restricted, with an ex-manufacturer price of A$17.96.

Regulatory history

SPIRACTIN was first registered on the ARTG on 14 October 1993 with ARTG registrations 46689 (25 mg) and 46691 (100 mg), both under licence category RE.