furosemide: clinical use

Prescribing considerations

• Correct clinically significant hypovolaemia, dehydration, hypotension and electrolyte or acid–base disturbance before treatment.
• Ensure urinary output is possible; partial urinary-tract obstruction can precipitate acute retention when diuresis begins.
• Use particular caution in older adults and people with renal or hepatic impairment, diabetes, gout, hypoproteinaemia, or concurrent hypotensive or nephrotoxic medicines.
• Injectable formulations require product-specific attention to route, administration rate, compatibility, dilution and protection from light.

Contraindications and cautions

• Hypersensitivity to furosemide or an excipient; sulfonamide cross-sensitivity is described in selected product information.
• Hypovolaemia or dehydration.
• Severe hypokalaemia or severe hyponatraemia.
• Anuria or anuric renal failure unresponsive to furosemide, including specified toxic or hepatic-coma contexts.
• Hepatic encephalopathy with pre-coma or coma.
• Breastfeeding under selected product licences.
• Some oral products additionally list Addison’s disease, porphyria or digitalis intoxication; verify the exact product information.

Monitoring

• Check blood pressure, electrolytes and renal function before treatment and after initiation or clinically significant changes.
• Continue periodic electrolyte and renal-function monitoring; monitor more closely with older age, chronic kidney disease, diabetes, acute fluid loss or relevant combination therapy.
• Assess volume status and investigate substantial deterioration in renal function.
• Consider glucose, uric acid, calcium, magnesium, bicarbonate and liver-related monitoring according to clinical risk.
• Monitor for hearing symptoms with injectable treatment or increased risk from renal impairment, hypoproteinaemia or ototoxic medicines.

Clinical pharmacology

Furosemide is a high-ceiling loop diuretic that inhibits the sodium–potassium–chloride cotransporter at the luminal surface of the thick ascending limb. Oral absorption is rapid but variable, protein binding is high, and elimination is predominantly renal; renal impairment can prolong elimination.

Formulation and product differences

• Tablets are solid oral preparations; selected oral solutions support patients unable to swallow tablets.
• Oral solutions differ in concentration, excipients, measuring devices and after-opening instructions, so prescribed volumes are not automatically interchangeable.
• Some selected oral solutions contain ethanol, maltitol and flavouring; check excipient suitability for the individual product.
• Injection and infusion products are for professional administration when oral treatment is unsuitable, ineffective or insufficiently rapid. Compatibility and handling instructions vary.

Solution for infusion

Route: Intravenous

Strengths: 10 mg/mL

Oral solution

Route: Oral

Strengths: 4 mg/mL, 8 mg/mL, 10 mg/mL, 20 mg/5 mL, 40 mg/5 mL, 50 mg/5 mL