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# Furosemide (Lasix)
## Overview
Furosemide is a loop diuretic used to treat fluid overload (edema) associated with heart failure, liver disease, and kidney disease, including nephrotic syndrome. It is also used to treat high blood pressure, alone or in combination with other antihypertensives.
## Primary Indications
* Edema due to heart failure, liver disease, or kidney disease
* Hypertension
## Adult Dosing
* **Edema:** 20 mg to 80 mg orally once daily. Doses may be increased by 20 mg to 40 mg every 6 to 8 hours until desired response is achieved. The usual maintenance dose is 40 mg to 80 mg once or twice daily. Maximum oral dose is typically 600 mg daily, but higher doses may be used in specific situations under close medical supervision.
* **Hypertension:** 40 mg orally twice daily. Doses may be adjusted as needed. Not typically recommended as a first-line agent for hypertension unless edema is also present.
## Pediatric Dosing
* **Edema:** 1 mg/kg to 2 mg/kg orally once daily. Maximum dose is 40 mg/day. Doses may be repeated every 6 hours if needed. For more severe edema, initial intravenous (IV) doses of 1 mg/kg may be administered, with a maximum of 20 mg per dose.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to reduced renal excretion and impaired receptor binding. However, cautious dose selection is warranted to avoid excessive diuresis and electrolyte disturbances.
* **Hepatic Impairment:** Cirrhosis with ascites may require careful dose titration to avoid precipitating hepatic coma.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* **Electrolyte Imbalance:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration:** Especially in the elderly.
* **Ototoxicity:** Hearing loss, tinnitus (more common with rapid IV administration or high doses).
* **Metabolic:** Hyperuricemia (can precipitate gout), hyperglycemia.
* **Other:** Dizziness, lightheadedness, orthostatic hypotension, rash.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects; may increase risk of renal impairment.
* **Antihypertensives:** Additive hypotensive effect.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced renal clearance of lithium, increasing the risk of lithium toxicity.
* **Potassium-Sparing Diuretics (e.g., Spironolactone):** Monitor potassium closely to avoid hyperkalemia.
## Monitoring
* Electrolytes (serum potassium, sodium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Fluid balance (intake and output, daily weight)
* Hearing (especially with high doses or rapid IV administration)
## Clinical Pearls
* Administer oral doses in the morning to minimize nocturia.
* Monitor for signs of dehydration and electrolyte depletion, particularly in elderly patients or those on concurrent therapies that affect electrolytes.
* Rapid IV administration can increase the risk of ototoxicity. Infuse slowly as recommended.
* Caution is advised when discontinuing furosemide in patients with chronic edema, as fluid may reaccumulate.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and relevant clinical guidelines for complete details and to verify drug information.*
