Frusemide

Loop Diuretic·Cardiovascular - Diuretics

Oedema associated with heart failure, hepatic cirrhosis, renal impairment

PBSDIURETICLasix, Urex20 mg tabletS4+1

Max Dose

1000 mg/day

Half-life

2 h

Hypokalemia

HIGH RISK

Dehydration

RISK

Rapid Summary

Overview

Potent loop diuretic. The absolute cornerstone for fluid offloading in acute pulmonary oedema (APO) and congestive heart failure. Induces massive, rapid diuresis.

Maximum Dose

Max 1000 mg/day (Only in severe end-stage renal failure. Standard max is usually 80-120 mg/day).

Clinical Focus

Potassium plummets rapidly. Proactive potassium replacement is almost always required during active diuresis.

Bottom Line

Frusemide is the most widely used loop diuretic for acute pulmonary oedema and fluid overload, but causes significant electrolyte depletion and ototoxicity at high IV doses.

Formulation & Access

Brand Names

Lasix, Urex

Oral Routes

Tablets (20 mg, 40 mg, 500 mg). Oral Liquid (10 mg/mL).

Parenteral

Ampoules (20 mg/2 mL, 250 mg/25 mL) for IV or IM use.

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Oedema associated with heart failure, hepatic cirrhosis, renal impairment.

Off-Label

OFF

Severe hypercalcemia (forces calcium excretion).

Clinical Place

First-line for symptomatic fluid overload. Not used for primary hypertension unless severe CKD is present.

Quick reference

Class & Role

Loop Diuretic — Potent loop diuretic.

Route / Formulation

Tablets (20 mg, 40 mg, 500 mg). Oral Liquid (10 mg/mL). (Lasix, Urex)

Usual Dose & Max

IV 20-50 mg STAT. May double dose and repeat if no diuresis within 1-2 hours. Max 1000 mg/day (Only in severe end-stage renal failure. Standard max is usually 80-120 mg/day).

Key Indication Doses

Acute Pulmonary Oedema: IV 20-50 mg STAT. May double dose and repeat if no diuresis within 1-2 hours. Heart Failure (Chronic): PO 20-80 mg OD or BD (usually morning and midday to prevent nocturia). Renal Impairment: Higher doses (e.g., 250 mg) are required as eGFR declines because the drug must reach the tubular lumen to work.

Best Uses

Frusemide is the most widely used loop diuretic for acute pulmonary oedema and fluid overload, but causes significant electrolyte depletion and ototoxicity at high IV doses.

Avoid / Cautions

Anuria, severe volume depletion, hepatic coma. Pregnancy Category C.

Key Risks

Electrolytes: Hypokalemia, hypomagnesemia, hyponatremia, hypocalcemia. Renal: Acute Kidney Injury (AKI) due to intravascular volume depletion. Neurological: Ototoxicity (deafness/tinnitus) if pushed too rapidly via IV or at massive doses. Metabolic: Hyperuricemia (precipitates gout).

Key Interactions

NSAIDs + ACEi/ARB + Frusemide = High risk of renal failure. Enhances lithium toxicity. Increases risk of digoxin toxicity via hypokalemia.

Monitoring

Strict fluid balance chart (input/output) and daily Weight. Daily U&E during acute IV diuresis to catch hypokalemia early.

Clinical Pearl

Oral bioavailability of frusemide is roughly 50%. Therefore, 40 mg PO = 20 mg IV. Remember this when stepping down therapy for discharge.

Access

Lasix, Urex20 mg tablet

Brand: Lasix, Urex
Formulation: Tablets (20 mg, 40 mg, 500 mg)

Frusemide

Loop Diuretic·Cardiovascular - Diuretics

Oedema associated with heart failure, hepatic cirrhosis, renal impairment

PBSDIURETICLasix, Urex20 mg tabletS4+1

Max Dose

1000 mg/day

Half-life

2 h

Hypokalemia

HIGH RISK

Dehydration

RISK

Rapid Summary

Overview

Potent loop diuretic. The absolute cornerstone for fluid offloading in acute pulmonary oedema (APO) and congestive heart failure. Induces massive, rapid diuresis.

Maximum Dose

Max 1000 mg/day (Only in severe end-stage renal failure. Standard max is usually 80-120 mg/day).

Clinical Focus

Potassium plummets rapidly. Proactive potassium replacement is almost always required during active diuresis.

Bottom Line

Frusemide is the most widely used loop diuretic for acute pulmonary oedema and fluid overload, but causes significant electrolyte depletion and ototoxicity at high IV doses.

Formulation & Access

Brand Names

Lasix, Urex

Oral Routes

Tablets (20 mg, 40 mg, 500 mg). Oral Liquid (10 mg/mL).

Parenteral

Ampoules (20 mg/2 mL, 250 mg/25 mL) for IV or IM use.

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Oedema associated with heart failure, hepatic cirrhosis, renal impairment.

Off-Label

OFF

Severe hypercalcemia (forces calcium excretion).

Clinical Place

First-line for symptomatic fluid overload. Not used for primary hypertension unless severe CKD is present.

Quick reference

Class & Role

Loop Diuretic — Potent loop diuretic.

Route / Formulation

Tablets (20 mg, 40 mg, 500 mg). Oral Liquid (10 mg/mL). (Lasix, Urex)

Usual Dose & Max

IV 20-50 mg STAT. May double dose and repeat if no diuresis within 1-2 hours. Max 1000 mg/day (Only in severe end-stage renal failure. Standard max is usually 80-120 mg/day).

Key Indication Doses

Best Uses

Frusemide is the most widely used loop diuretic for acute pulmonary oedema and fluid overload, but causes significant electrolyte depletion and ototoxicity at high IV doses.

Avoid / Cautions

Anuria, severe volume depletion, hepatic coma. Pregnancy Category C.

Key Risks

Key Interactions

NSAIDs + ACEi/ARB + Frusemide = High risk of renal failure. Enhances lithium toxicity. Increases risk of digoxin toxicity via hypokalemia.

Monitoring

Strict fluid balance chart (input/output) and daily Weight. Daily U&E during acute IV diuresis to catch hypokalemia early.

Clinical Pearl

Oral bioavailability of frusemide is roughly 50%. Therefore, 40 mg PO = 20 mg IV. Remember this when stepping down therapy for discharge.

Access

Lasix, Urex20 mg tablet

Brand: Lasix, Urex
Formulation: Tablets (20 mg, 40 mg, 500 mg)