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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to reduce fluid overload.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with hepatic cirrhosis
* Edema associated with renal disease, including nephrotic syndrome
* Hypertension (adjunctive therapy)
## Adult Dosing
* **Edema:**
* Oral: Typically starts at 20-80 mg once daily. May be given as a single dose or divided doses. The dose can be increased by 20-40 mg every 6-8 hours as needed until desired diuresis is achieved.
* IV/IM: Typically starts at 20-40 mg once daily. May be given as a single dose or divided doses.
* Maximum oral dose: 600 mg/day (higher doses may be used in specific refractory cases under close medical supervision).
* Maximum IV/IM dose: 200 mg in a single dose (higher doses may be used in specific refractory cases under close medical supervision, typically with continuous infusion).
* **Hypertension:**
* Oral: Typically 40 mg twice daily. Not usually a first-line agent for hypertension alone.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once or twice daily.
* IV/IM: 1 mg/kg/dose once daily.
* Maximum dose: 6 mg/kg/dose or 40 mg/dose for oral, and 1 mg/kg/dose or 20 mg/dose for IV/IM. Higher doses may be considered in specific situations.
## Dose Adjustments
* **Renal Impairment:** May require higher doses to achieve the same diuretic effect. Closely monitor fluid and electrolytes.
* **Hepatic Impairment:** Use with caution; can precipitate hepatic coma. Monitor electrolytes and fluid status closely.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* **Common:** Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, dizziness, lightheadedness, hyperuricemia, hyperglycemia.
* **Less Common/Serious:** Ototoxicity (especially with rapid IV administration or high doses), photosensitivity, rash, Stevens-Johnson syndrome, aplastic anemia, agranulocytosis, thrombocytopenia, pancreatitis, renal failure.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Antihypertensives (including ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Digoxin:** Risk of digoxin toxicity is increased with furosemide-induced hypokalemia.
* **NSAIDs:** May reduce the natriuretic and diuretic effects of furosemide and increase the risk of nephrotoxicity.
* **Potassium-sparing diuretics (e.g., spironolactone, amiloride):** Monitor potassium levels closely due to counteracting effects.
* **Thiazide diuretics:** Additive diuresis and electrolyte depletion.
## Monitoring
* **Daily:** Weight, urine output, blood pressure.
* **Regularly:** Serum electrolytes (sodium, potassium, chloride, magnesium, calcium), BUN, creatinine, glucose, uric acid.
* **As indicated:** Hearing assessment (especially with high doses or IV administration).
## Clinical Pearls
* Administer IV furosemide slowly (e.g., over 30-60 minutes) to minimize the risk of ototoxicity. Rapid IV injection can lead to transient hearing loss.
* Oral administration can be done with or without food.
* If a patient is unresponsive to oral furosemide, consider switching to IV administration.
* Electrolyte replacement (especially potassium) is often necessary during therapy.
* Consider initiating therapy with lower doses and titrating based on response and patient tolerance, especially in elderly patients or those with significant comorbidities.
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***Disclaimer:** This information is intended for healthcare professionals. Always consult the official prescribing information and current clinical guidelines for complete details before making any treatment decisions. Dosing and management may vary based on individual patient factors and local protocols.*
