Please check your internet connection and try again.
# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium and chloride in the ascending limb of the loop of Henle, leading to increased excretion of water, sodium, chloride, potassium, and hydrogen ions.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with hepatic cirrhosis
* Edema associated with renal disease, including the nephrotic syndrome
* Hypertension (may be used in addition to other antihypertensives)
## Adult Dosing
* **Edema:** Oral: 20-80 mg once daily. May increase by 20-40 mg every 6-8 hours as needed. Doses above 80 mg orally may be less effective and increase the risk of adverse effects. Maximum oral dose is typically 600 mg/day, but higher doses may be used under close medical supervision. Intravenous (IV)/Intramuscular (IM): 20-40 mg once daily. May increase by 20 mg every 2 hours as needed. Maximum IV/IM dose is typically 200 mg in a single dose, but higher doses may be used under close medical supervision.
* **Hypertension:** Oral: 40 mg twice daily.
## Pediatric Dosing
* **Edema:** Oral: 1-2 mg/kg/dose once daily. May increase by 1-2 mg/kg/dose every 6-8 hours. Maximum dose: 6 mg/kg/day.
* **Hypertension:** Oral: 0.5-1 mg/kg/dose once daily. Maximum dose: 40 mg/day.
* IV/IM: 1 mg/kg/dose. Maximum dose: 20 mg. May repeat every 2 hours. Higher doses may be needed in neonates or children with severe renal dysfunction.
## Dose Adjustments
* **Renal Impairment:** Dosage may need to be increased in patients with renal impairment due to decreased glomerular filtration and impaired secretion into the renal tubules. Conversely, dosage may need to be reduced in patients with impaired renal function to avoid excessive diuresis. Specific dosing adjustments depend on the degree of renal impairment and patient response.
* **Hepatic Impairment:** Patients with hepatic cirrhosis may be more sensitive to the effects of furosemide, particularly regarding electrolyte disturbances and fluid and electrolyte balance. Lower doses may be required.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur)
* Severe electrolyte depletion (e.g., hypokalemia, hyponatremia)
## Adverse Effects
* **Common:** Dizziness, lightheadedness, orthostatic hypotension, dehydration, hypokalemia, hyponatremia, hypochloremia, metabolic alkalosis, hyperglycemia, hyperuricemia.
* **Serious:** Severe electrolyte imbalances, renal failure, ototoxicity (especially with rapid IV administration or high doses), Stevens-Johnson syndrome, aplastic anemia, thrombocytopenia, agranulocytosis.
## Key Drug Interactions
* **Aminoglycosides (e.g., gentamicin, amikacin):** Increased risk of ototoxicity and nephrotoxicity.
* **Antihypertensives (e.g., ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effects. May require blood pressure monitoring and dose adjustments.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs (e.g., ibuprofen, naproxen):** May reduce the diuretic and antihypertensive effects of furosemide and potentiate nephrotoxicity.
* **Potassium-sparing diuretics (e.g., spironolactone, amiloride):** May counteract the potassium-wasting effects of furosemide but increase the risk of hyperkalemia if not carefully monitored.
* **Lithium:** Reduced renal clearance of lithium, increasing the risk of lithium toxicity.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid balance (intake and output, daily weights)
* Blood pressure
* Blood glucose (in diabetic patients)
* Uric acid
* Auditory function (especially with high doses or rapid IV administration)
## Clinical Pearls
* Oral administration is preferred when possible.
* Furosemide is most effective when given on an empty stomach, but may be given with food or milk if gastric irritation occurs.
* Rapid IV administration can cause ototoxicity. Administer IV infusions slowly, typically over 30-60 minutes.
* Monitor for signs and symptoms of electrolyte depletion, especially hypokalemia (muscle weakness, cramps, arrhythmias).
* Educate patients about potential side effects, including dizziness and orthostatic hypotension, and advise them to rise slowly from a sitting or lying position.
* In patients with edema due to CHF or cirrhosis, daily weight monitoring is crucial to assess fluid status.
***
*This information is intended for healthcare professionals and should not be used as a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines for complete details.*
