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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) and high blood pressure. It works by inhibiting the reabsorption of sodium and chloride in the kidneys, leading to increased urine output.
## Primary Indications
* Edema associated with heart failure, liver disease, or kidney disease (including nephrotic syndrome).
* Hypertension (often in combination with other antihypertensives).
## Adult Dosing
* **Edema:** Oral: 20-80 mg once daily. Higher doses may be needed, typically divided every 12-24 hours. Maximum recommended oral dose is 600 mg daily, but doses up to 1 g daily have been used in severe cases under close monitoring. Intravenous/Intramuscular: 20-40 mg once daily. May be given as a continuous infusion in refractory edema.
* **Hypertension:** Oral: 20-40 mg twice daily.
## Pediatric Dosing
* **Edema:** Oral: 1-4 mg/kg/day divided every 12-24 hours. Maximum 6 mg/kg/day. Intravenous/Intramuscular: 1 mg/kg/dose, not to exceed 20 mg/dose. May be repeated every 6-12 hours. For continuous infusion: 0.1 mg/kg/hour.
## Dose Adjustments
* **Renal Impairment:** Patients with renal impairment may require higher doses due to decreased drug excretion. Monitor closely.
* **Hepatic Impairment:** Use with caution; may precipitate hepatic coma.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia).
* Dehydration.
* Ototoxicity (especially with rapid IV administration or high doses).
* Hypotension.
* Hyperuricemia (may precipitate gout).
* Hyperglycemia.
* Dizziness, lightheadedness.
* Photosensitivity.
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **ACE inhibitors and ARBs:** Increased risk of hypotension and renal dysfunction.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May blunt the diuretic and antihypertensive effects of furosemide and increase the risk of renal dysfunction.
* **Lithium:** Decreased renal clearance of lithium, increasing risk of lithium toxicity.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid status (weight, intake/output)
* Blood pressure
* Hearing (if indicated)
## Clinical Pearls
* Administer oral furosemide on an empty stomach if possible for maximum absorption, but may be taken with food or milk if gastric upset occurs.
* Rapid IV administration can lead to ototoxicity; infuse slowly.
* Monitor for signs of dehydration and electrolyte depletion.
* Potassium supplementation is often required, especially with higher doses.
* Patients with edema may have significant daily weight fluctuations due to fluid shifts; monitor weight regularly.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and a qualified healthcare provider for any medical decisions.*
