LASIX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for LASIX (LASIX).

How it works

Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, reducing sodium, chloride, and water reabsorption and increasing urinary output.

What the body does with it

Metabolism	Furosemide is metabolized primarily by glucuronidation via UGT1A1, with minimal hepatic metabolism; about 50% is excreted unchanged in urine.
Excretion	Primarily renal excretion (50-80% as unchanged drug) via glomerular filtration and proximal tubular secretion; minor fecal elimination (<5%).
Half-life	Terminal elimination half-life is approximately 1.5-2 hours. In renal impairment (CrCl <20 mL/min), half-life may prolong to up to 2-4 hours; in end-stage renal disease or heart failure, may exceed 4 hours.
Protein binding	91-99% bound, primarily to albumin.
Volume of Distribution	0.1-0.2 L/kg in healthy adults; increases in conditions with reduced plasma protein binding (e.g., nephrotic syndrome) or fluid overload (e.g., heart failure) up to 0.3-0.8 L/kg.
Bioavailability	Oral: 60-70% (range 50-80%); decreased by food; intravenous: 100%.
Onset of Action	Oral: 30-60 minutes. Intravenous: 5 minutes (within 30 minutes of administration). Intramuscular: 30 minutes.
Duration of Action	Oral: 4-6 hours. Intravenous: Approximately 2 hours. Diuresis typically ends within 6-8 hours; in renal impairment, duration may be prolonged.

Classification & Brands

Action Class	High-ceiling Diuretics (Inhibitors of Na+-K+- 2Cl cotransport)
Brand Substitutes	Lasipen 40mg Tablet, FRUSAMIDE 40 MG TABLET, Cgfru 40mg Tablet, Frusenex 40mg Tablet, Oroside 40 Tablet, Frusizex 10mg Injection, Urix 10mg/ml Injection, Lasibrace Injection, FRU 20 MG INJECTION, Lasarc 20mg Injection, Casix 20mg Injection, Lasiwin 20mg Injection, Lasitag 20mg Injection

Dosing & administration

20-80 mg IV or PO once or twice daily; maximum 600 mg/day IV or PO.

Dosage form	INJECTABLE
Renal impairment	GFR 10-50 mL/min: dose every 12 hours; GFR <10 mL/min: avoid use or use with extreme caution.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated or avoid.
Pediatric use	1-2 mg/kg/dose PO or IV every 6-12 hours; maximum 6 mg/kg/day.
Geriatric use	Start at 20 mg/day PO or 20 mg IV, titrate slowly due to increased sensitivity and risk of electrolyte disturbances.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for LASIX (LASIX).

Breastfeeding	Furosemide is excreted into breast milk in low amounts. M/P ratio approximately 1:1. No adverse effects reported in infants, but may suppress lactation. Use with caution, especially in neonates.
Teratogenic Risk	Furosemide crosses the placenta. First trimester: limited data, no clear teratogenic pattern; risk cannot be excluded. Second and third trimesters: may cause maternal hypovolemia, decreased placental perfusion, electrolyte imbalances, and fetal dehydration; oligohydramnios reported. Use only if clearly needed.

Warnings & precautions

■ FDA Black Box Warning

Furosemide is a potent diuretic. If given in excessive amounts, it can lead to profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required, and dose and dose schedule must be adjusted to the individual patient's needs.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Anuria","History of hypersensitivity to furosemide or sulfonamides"]

Clinical Precautions

Precautions

["Risk of hypovolemia, dehydration, and electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)","Ototoxicity, especially with rapid injection or severe renal impairment","Sulfonamide cross-sensitivity"]

Clinical Tips & Counseling

Drug interactions

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LASIX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for LASIX (LASIX).

How it works

Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, reducing sodium, chloride, and water reabsorption and increasing urinary output.

What the body does with it

Metabolism	Furosemide is metabolized primarily by glucuronidation via UGT1A1, with minimal hepatic metabolism; about 50% is excreted unchanged in urine.
Excretion	Primarily renal excretion (50-80% as unchanged drug) via glomerular filtration and proximal tubular secretion; minor fecal elimination (<5%).
Half-life	Terminal elimination half-life is approximately 1.5-2 hours. In renal impairment (CrCl <20 mL/min), half-life may prolong to up to 2-4 hours; in end-stage renal disease or heart failure, may exceed 4 hours.
Protein binding	91-99% bound, primarily to albumin.
Volume of Distribution	0.1-0.2 L/kg in healthy adults; increases in conditions with reduced plasma protein binding (e.g., nephrotic syndrome) or fluid overload (e.g., heart failure) up to 0.3-0.8 L/kg.
Bioavailability	Oral: 60-70% (range 50-80%); decreased by food; intravenous: 100%.
Onset of Action	Oral: 30-60 minutes. Intravenous: 5 minutes (within 30 minutes of administration). Intramuscular: 30 minutes.
Duration of Action	Oral: 4-6 hours. Intravenous: Approximately 2 hours. Diuresis typically ends within 6-8 hours; in renal impairment, duration may be prolonged.

Classification & Brands

Action Class	High-ceiling Diuretics (Inhibitors of Na+-K+- 2Cl cotransport)
Brand Substitutes	Lasipen 40mg Tablet, FRUSAMIDE 40 MG TABLET, Cgfru 40mg Tablet, Frusenex 40mg Tablet, Oroside 40 Tablet, Frusizex 10mg Injection, Urix 10mg/ml Injection, Lasibrace Injection, FRU 20 MG INJECTION, Lasarc 20mg Injection, Casix 20mg Injection, Lasiwin 20mg Injection, Lasitag 20mg Injection

Dosing & administration

20-80 mg IV or PO once or twice daily; maximum 600 mg/day IV or PO.

Dosage form	INJECTABLE
Renal impairment	GFR 10-50 mL/min: dose every 12 hours; GFR <10 mL/min: avoid use or use with extreme caution.
Liver impairment	Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated or avoid.
Pediatric use	1-2 mg/kg/dose PO or IV every 6-12 hours; maximum 6 mg/kg/day.
Geriatric use	Start at 20 mg/day PO or 20 mg IV, titrate slowly due to increased sensitivity and risk of electrolyte disturbances.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for LASIX (LASIX).

Breastfeeding	Furosemide is excreted into breast milk in low amounts. M/P ratio approximately 1:1. No adverse effects reported in infants, but may suppress lactation. Use with caution, especially in neonates.
Teratogenic Risk	Furosemide crosses the placenta. First trimester: limited data, no clear teratogenic pattern; risk cannot be excluded. Second and third trimesters: may cause maternal hypovolemia, decreased placental perfusion, electrolyte imbalances, and fetal dehydration; oligohydramnios reported. Use only if clearly needed.

Warnings & precautions

■ FDA Black Box Warning

Side Effect Profile

Serious Effects

Absolute Contraindications

["Anuria","History of hypersensitivity to furosemide or sulfonamides"]

Clinical Precautions

Precautions

Clinical Tips & Counseling

Drug interactions

Loading safety data…