Dosing and uses of Lasix (furosemide)
Adult dosage forms and strengths
injectable solution
- 10mg/mL
oral solution
- 10mg/mL
- 8mg/mL
tablet
- 20mg
- 40mg
- 80mg
Edema
Edema associated with congestive heart failure (CHF), liver cirrhosis, and renal disease, including nephrotic syndrome
20-80 mg PO once daily; may be increased by 20-40 mg q6-8hr; not to exceed 600 mg/day
Alternative: 20-40 mg IV/IM once; may be increased by 20 mg q2hr; individual dose not to exceed 200 mg/dose
Refractory CHF may necessitate larger doses
Hypertension, Resistant
20-80 mg PO divided q12hr
Acute Pulmonary Edema/Hypertensive Crisis/Increased Intracranial Pressure
0.5-1 mg/kg (or 40 mg) IV over 1-2 minutes; may be increased to 80 mg if there is no adequate response within 1 hour;not to exceed 160-200 mg/dose
Hyperkalemia in Advanced Cardiac Life Support (ACLS)
40-80 mg IV
Hypermagnesemia in ACLS
20-40 mg IV q3-4hr PRn
Dosing Modifications
Acute renal failure: 1-3 g/day may be necessary to attain desired response; avoid use in oliguric states
Hepatic impairment: Monitor, especially with high dosages
Dosing Considerations
Use for fluid retention refractory to thiazides or impaired renal function
Overdose management
- Normal saline may be used for volume replacement
- Dopamine or norepinephrine may be used to treat hypotension
- If dysrhythmia due to decreased potassium or magnesium is suspected, replace aggressively
- Discontinue treatment if no symptoms are apparent after 6 hours
Pediatric dosage forms and strengths
injectable solution
- 10mg/mL
oral solution
- 10mg/mL
- 8mg/mL
tablet
- 20mg
- 40mg
- 80mg
Edema
Infants and children: 1-2 mg/kg IV/IM/PO once initially; increased by 1-2 mg/kg q6-8hr (PO) or 1 mg/kg q2hr (IV/IM); individual dose not to exceed 6 mg/kg
Neonates (<28 days): 0.5-1 mg/kg IV/IM q8-24hr; individual dose not to exceed 2 mg/kg
Resistant Hypertension
<1 year: Safety and efficacy not established
1-17 years: 0.5-2 mg/kg PO q24hr or q12hr; individual dose not to exceed 6 mg/kg/dose
Geriatric dosage forms and strengths
Excessive diuresis may cause dehydration and electrolyte loss in elderly; lower initial dosages and more gradual adjustments are recommended (eg, 10 mg/day PO)
Increase in blood urea nitrogen (BUN) and loss of sodium may cause confusion in elderly; monitor renal function and electrolytes
Edema
20 mg/day PO/IV/IM initially; increased slowly until desired response is obtained
Lasix (furosemide) adverse (side) effects
>10%
Hyperuricemia (40%)
Hypokalemia (14-60%)
Frequency not defined
Anaphylaxis
Anemia
Anorexia
Diarrhea
Dizziness
Glucose intolerance
Glycosuria
Headache
Hearing impairment
Hyperuricemia
Hypocalcemia
Hypokalemia
Hypomagnesemia
Hypotension
Increased patent ductus arteriosus during neonatal period
Muscle cramps
Nausea
Photosensitivity
Rash
Restlessness
Tinnitus
Urinary frequency
Urticaria
Vertigo
Weakness
Warnings
Black box warnings
Agent is potent diuretic that, if given in excessive amounts, may lead to profound diuresis with water and electrolyte depletion
Careful medical supervision is required; dosing must be adjusted to patient's needs
Contraindications
Documented hypersensitivity to furosemide or sulfonamides
Anuria
Cautions
Use caution in systemic lupus erythematosus, liver disease, renal impairment
Concomitant ethacrynic acid therapy (increases risk of ototoxicity)
Risks of fluid or electrolyte imbalance (including causing hyperglycemia, hyperuricemia, gout), hypotension, metabolic alkalosis, severe hyponatremia, severe hypokalemia, hepatic coma and precoma, hypovolemia (with or without hypotension)
Do not commence therapy in hepatic coma and in electrolyte depletion until improvement is noted
IV route twice as potent as PO
Food delays absorption but not diuretic response
May exacerbate lupus
Possibility of skin sensitivity to sunlight
Prolonged use in premature neonates may cause nephrocalcinosis
Efficacy is diminished and risk of ototoxicity increased in patients with hypoproteinemia (associated with nephrotic syndrome); ototoxicity is associated with rapid injection, severe renal impairment, use of higher than recommended doses, concomitant therapy with aminoglycoside antibiotics, ethacrynic acid, or other ototoxic drugs
To prevent oliguria, reversible increases in BUN and creatinine, and azotemia, monitor fluid status and renal function; discontinue therapy if azotemia and oliguria occur during treatment of severe progressive renal disease
FDA-approved product labeling for many medications have included a broad contraindication in patients with a prior allregic reaction to sulfonamides; however, recent studies have suggested that crossreactivity between antibiotic sulfonamides and nonantibiotic sulfonamides is unlikely to occur
In cirrhosis, electrolyte and acid/base imbalances may lead to hepatic encephalopathy; prior to initiation of therapy, correct electrolyte and acid/base imbalances, when hepatic coma is present
High doses (> 80 mg) of furosemide may inhibit binding of thyroid hormones to carrier proteins and result in transient increase in free thyroid hormones, followed by overall decrease in total thyroid hormone levels
In patients at high risk for radiocontrast nephropathy furosemide can lead to higher incidence of deterioration in renal function after receiving radiocontrast compared to high-risk patients who received only intravenous hydration prior to receiving radiocontrast
Observe patients regularly for possible occurrence of blood dyscrasias, liver or kidney damage, or other idiosyncratic reactions
Hearing loss in neonates has been associated with use of furosemide injection; in premature neonates with respiratory distress syndrome, diuretic treatment with furosemide in the first few weeks of life may increase risk of persistent patent ductus arteriosus (PDA), possibly through a prostaglandin-E-mediated process
Excessive diuresis may cause dehydration and blood volume reduction with circulatory collapse and possibly vascular thrombosis and embolism, particularly in elderly patients
Increases in blood glucose and alterations in glucose tolerance tests (with abnormalities of fasting and 2 hour postprandial sugar) have been observed, and rarely, precipitation of diabetes mellitus reported
Patients with severe symptoms of urinary retention (because of bladder emptying disorders, prostatic hyperplasia, urethral narrowing), the administration of furosemide can cause acute urinary retention related to increased production and retention of urine; these patients require careful monitoring, especially during initial stages of treatment
Pregnancy and lactation
Pregnancy category: C; treatment during pregnancy necessitates monitoring of fetal growth because of risk for higher fetal birth weights
Lactation: Drug excreted into breast milk; use with caution; may inhibit lactation
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Lasix (furosemide)
Mechanism of action
Loop diuretic; inhibits reabsorption of sodium and chloride ions at proximal and distal renal tubules and loop of Henle; by interfering with chloride-binding cotransport system, causes increases in water, calcium, magnesium, sodium, and chloride
Absorption
Bioavailability: 47-64% (PO)
Onset: 30-60 min (PO/SL); 30 min (IM); 5 min (IV)
Peak effect: <15 min (IV); 1-2 hr (PO/SL)
Duration: 2 hr (IV); 6-8 hr (PO)
Distribution
Protein bound: 91-99%
Vd: 0.2 L/kg
Metabolism
Metabolized in liver (~10%)
Metabolite: Glucuronide (2-amino-4-chloro-5-sulfamoylanthranilic acid [saluamine]) (activity unknown)
Elimination
Half-life: 30-120 min (normal renal function); 9 hr (end-stage renal disease)
Dialyzable: No
Renal clearance: 2 mL/min/kg
Excretion: Urine (PO, 50%; IV, 80%)
Administration
IV Incompatibilities
Solution: Fructose10W, invert sugar 10% in multiple electrolyte #2
Additive: Amiodarone (at high concentrations of both drugs), buprenorphine, chlorpromazine, diazepam, dobutamine, eptifibatide, erythromycin lactobionate, gentamicin(?), hydrocortisone(?), isoproterenol, meperidine, metoclopramide, netilmicin, papaveretum, prochlorperazine, promethazine
Syringe: Caffeine, doxapram, doxorubicin, eptifibatide, metoclopramide, milrinone, droperidol, vinblastine, vincristine
Y-site: Alatrofloxacin, amiodarone (incompatible at furosemide 10 mg/mL; possibly compatible at 1 mg/mL), chlorpromazine, ciprofloxacin, cisatracurium (incompatible at cisatracurium >2 mg/mL; possibly compatible at 0.1 mg/mL), clarithromycin, diltiazem, diphenhydramine, dobutamine, dopamine, doxorubicin (incompatible at furosemide 10 mg/mL and doxorubicin 2 mg/mL; possibly compatible at furosemide 3 mg/mL and doxorubicin 0.2 mg/mL), droperidol, eptifibatide, esmolol, famotidine(?), fenoldopam, gatifloxacin, gemcitabine, gentamicin(?), hydralazine, idarubicin, labetalol, levofloxacin, meperidine, metoclopramide, midazolam, milrinone, morphine, netilmicin, nicardipine, ondansetron, quinidine, thiopental, vecuronium, vinblastine, vincristine, vinorelbine
Not specified: Tetracycline
IV Compatibilities
Additive: Cimetidine, epinephrine, heparin, nitroglycerin, potassium chloride, verapamiL
Syringe: Heparin
Y-site: Epinephrine, fentanyl, heparin, norepinephrine, nitroglycerin, potassium chloride, verapamil(?), vitamins B and C
IV Preparation
Solution: No preparation needed (available form: 10 mg/mL)
IV Administration
Injection: Inject directly or into tubing of actively running IV over 1-2 minutes
Administer undiluted IV injections at rate of 20-40 mg/min; not to exceed 4 mg/min for short-term intermittent infusion; in children, give 0.5 mg/kg/min, titrated to effect
Use infusion solution within 24 hours
