LASIX ONYU
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LASIX ONYU (LASIX ONYU).
Lasix (furosemide) inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle, reducing sodium, chloride, and water reabsorption.
| Metabolism | Furosemide is primarily metabolized by glucuronidation via UGT1A9 and UGT1A1; minor metabolism via cytochrome P450 (CYP) enzymes. |
| Excretion | Primarily renal (50-80% as unchanged drug); biliary/fecal (20-30%); non-renal clearance accounts for up to 20%. |
| Half-life | 1.5-2.0 hours in normal renal function; prolonged to 10-15 hours in severe renal impairment (CrCl <10 mL/min); clinically significant accumulation risk with repeated dosing in renal disease. |
| Protein binding | >99% bound, primarily to albumin; binding saturable at high doses, increasing free fraction and toxicity risk. |
| Volume of Distribution | 0.11-0.22 L/kg; small Vd reflects extensive protein binding and limited tissue penetration; increases in hypoalbuminemia. |
| Bioavailability | Oral: 60-70% (range 40-90%); reduced with food; Intramuscular: approximately 100% but slower absorption than IV. |
| Onset of Action | Oral: 30-60 minutes; Intravenous: 5 minutes; Intramuscular: 30 minutes. |
| Duration of Action | Oral: 6-8 hours; Intravenous: 2-3 hours; duration prolonged in renal impairment; diuretic effect may persist after measurable drug levels decline. |
Furosemide 20-80 mg IV/PO once or twice daily; max 600 mg/day for IV, 80 mg/day for PO.
| Dosage form | SOLUTION |
| Renal impairment | eGFR <30 mL/min/1.73m2: increase interval to every 12-24h or use higher doses (up to 160 mg IV) due to reduced efficacy; avoid in anuria. |
| Liver impairment | Child-Pugh A-B: start at lowest dose and titrate cautiously due to risk of diuretic-induced encephalopathy; Child-Pugh C: contraindicated or use with extreme caution, avoid if possible. |
| Pediatric use | IV: 1 mg/kg/dose every 6-12h; PO: 2 mg/kg/dose every 6-12h; max 6 mg/kg/dose. |
| Geriatric use | Start at 20 mg PO/IV once daily; titrate slowly due to increased sensitivity, risk of electrolyte imbalance and dehydration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LASIX ONYU (LASIX ONYU).
| Breastfeeding | Furosemide is excreted into breast milk in low amounts (M/P ratio approximately 0.06-0.1). No adverse effects reported in infants; however, due to risk of deafness and electrolyte imbalance, caution is advised. Consider deferring breastfeeding if high maternal doses are required. |
| Teratogenic Risk | First trimester: Limited data; no clear evidence of major malformations from human studies, but animal studies show embryo-fetal toxicity at high doses. Second and third trimesters: May cause electrolyte imbalances, ototoxicity, and potential fetal renal impairment. Use only if clearly needed. |
■ FDA Black Box Warning
Furosemide is a potent diuretic which, if given in excessive amounts, can lead to a profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required and dose adjustment must be based on individual response.
| Serious Effects |
["Anuria","Hypersensitivity to furosemide or sulfonamides","Severe electrolyte depletion (hypokalemia, hyponatremia)","Hepatic coma or pre-coma"]
| Precautions | ["Monitor for hypotension and electrolyte imbalances (hypokalemia, hyponatremia, hypomagnesemia)","Ototoxicity (especially in patients with renal impairment or rapid IV administration)","Can precipitate acute urinary retention in patients with prostatic hyperplasia","May cause hyperuricemia and precipitate gout","Monitor renal function and blood glucose (can cause hyperglycemia)"] |
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| Fetal Monitoring | Monitor maternal serum electrolytes, renal function, blood pressure, and uric acid. Monitor fetal growth and amniotic fluid volume via ultrasound if used chronically. Assess infant for electrolyte disturbances and ototoxicity postpartum. |
| Fertility Effects | No direct studies on fertility in humans; however, furosemide may affect renal function and electrolyte balance, potentially impacting menstrual cycle and fertility indirectly. Animal studies show no significant impairment. |