spironolactone: clinical use

Prescribing considerations

• Review renal and hepatic function, fluid status, potassium intake, interacting medicines and urinary-obstruction risk.
• Children should be managed under paediatric specialist guidance; evidence is limited.
• Avoid unsupervised switching between Urospir and other spironolactone products because exposure may differ.
• Consider product excipients and administration requirements, particularly sucrose and sodium benzoate in Qaialdo.

Contraindications and cautions

• Acute renal insufficiency, significant renal impairment or anuria.
• Pre-existing hyperkalaemia.
• Addison's disease.
• Hypersensitivity to spironolactone or a formulation excipient.
• Concomitant eplerenone or another potassium-sparing diuretic.
• Moderate-to-severe renal impairment in paediatric patients.

Monitoring

• Check renal function and electrolytes, including potassium, before treatment where clinically indicated.
• Repeat renal function and potassium after initiation or treatment changes and periodically thereafter, with closer surveillance in heart failure, older people, renal or hepatic impairment, and interacting treatment.
• Assess fluid balance, blood pressure and adverse endocrine effects.
• Advise patients to seek prescriber advice during significant vomiting, diarrhoea, fever or sweating because dehydration may worsen renal dysfunction and hyperkalaemia.

Clinical pharmacology

Spironolactone competitively antagonises aldosterone and is metabolised to active compounds, including canrenone. It produces a gradual, prolonged potassium-sparing natriuretic effect and also has androgen-receptor activity.

Formulation and product differences

• Aldactone is a film-coated tablet.
• Qaialdo is a sucrose-containing oral suspension that must be shaken; it includes two measuring syringes and may be administered through a suitable nasogastric tube.
• Urospir is a non-aqueous oral solution containing medium-chain triglycerides and peppermint oil. It is incompatible with water, PVC and polystyrene, is not recommended for enteral tubes, and is not bioequivalent to the reference tablet.
• Spironolactone Waymade is a clear oral solution containing medium-chain triglycerides, peppermint oil and an antioxidant, supplied with an oral syringe and bottle adaptor.

Oral solution

Route: Oral

Strengths: 25 mg/5 mL, 50 mg/5 mL

Oral suspension

Route: Oral

Strengths: 10 mg/mL

Tablet

Route: Oral

Strengths: 12.5 mg, 25 mg, 50 mg, 100 mg