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. |
| Molecular Weight | 330.745 |
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 | Furosemide crosses the placenta. Use only if potential benefit outweighs risk; associated with oligohydramnios and fetal renal effects. |
| 2nd trimester | Limited data; may cause electrolyte imbalances in fetus. Use with caution. |
| 3rd trimester | May cause oligohydramnios, fetal renal dysfunction, or electrolyte disturbances. Avoid if possible. |
Clinical note
Comprehensive clinical and safety monograph for LASIX ONYU (LASIX ONYU).
| Placental transfer | Crosses placenta; detectable in fetal plasma and amniotic fluid. |
| Breastfeeding | Furosemide is excreted into breast milk in small amounts. However, due to potential for ototoxicity and diuresis in the infant, caution is advised. Monitor infant for signs of dehydration or electrolyte imbalance. |
■ 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 |
AnuriaHypersensitivity to furosemide or sulfonamidesSevere electrolyte depletionHepatic coma or precoma
| 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) |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they may increase furosemide levels and risk of toxicity. Potassium-rich foods (e.g., bananas, oranges, leafy greens) may be encouraged if hypokalemia develops, but only under medical advice. Limit sodium intake to reduce fluid retention and manage hypertension. Avoid excessive alcohol intake as it can increase blood pressure and impair diuresis. |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) |
| 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. |
| 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. |
| Clinical Pearls | Furosemide (Lasix) is a loop diuretic used for edema and hypertension. Onset of diuresis is within 1 hour after oral administration. Monitor for hypokalemia, hyponatremia, and hypomagnesemia; use with caution in patients with sulfonamide allergy. Ototoxicity may occur with rapid IV administration or high doses, especially in renal impairment. For severe fluid overload, administer IV slowly over 1-2 minutes. In heart failure, diuresis may require upward titration. |
| Patient Advice | Take Lasix exactly as prescribed, usually once or twice daily. Take it in the morning to avoid nighttime urination. · Avoid sudden changes in position; may cause dizziness or lightheadedness due to blood pressure drop. · Monitor weight daily and report significant changes. If weight gain of >2-3 pounds in a day or >5 pounds in a week, contact your doctor. · Stay hydrated unless fluid restriction is advised. This is especially important in hot weather or during exercise. · Do not take with grapefruit or grapefruit juice; may increase side effects. |