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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) and high blood pressure.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease.
* Hypertension (often in combination with other antihypertensives).
## Adult Dosing
* **Edema:**
* Oral: 20-80 mg once daily, may be increased in increments of 20-40 mg every 6-8 hours as needed. Maximum daily dose is typically 600 mg, but may be higher in refractory cases under close monitoring.
* Intravenous/Intramuscular: 20-40 mg once daily, may be increased in increments of 20 mg every 2 hours. Continuous IV infusion may be considered for severe edema. Maximum IV dose is typically 600 mg/day, but higher doses may be used cautiously.
* **Hypertension:**
* Oral: 40 mg twice daily. Not typically a first-line agent for hypertension alone.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once or twice daily. Maximum single dose is 6 mg/kg.
* Intravenous/Intramuscular: 1 mg/kg/dose, not to exceed 20 mg per dose. May be repeated every 6 hours as needed. For chronic edema, higher doses may be used under specialist guidance.
## Dose Adjustments
* **Renal Impairment:** Higher doses may be required due to decreased efficacy, but monitor closely for electrolyte abnormalities and ototoxicity.
* **Hepatic Impairment:** May require dose reduction due to impaired metabolism and increased sensitivity to fluid and electrolyte loss.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur).
* Severe electrolyte depletion (e.g., hyponatremia, hypokalemia).
## Adverse Effects
* Electrolyte abnormalities (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia).
* Dehydration.
* Ototoxicity (especially with rapid IV administration or high doses).
* Hypotension.
* Hyperuricemia, hyperglycemia.
* Dizziness, lightheadedness.
* Rash.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects; increased risk of renal impairment.
* **ACE Inhibitors/ARBs:** Increased risk of symptomatic hypotension and renal dysfunction.
* **Digoxin:** Increased risk of digoxin toxicity due to hypokalemia.
* **Lithium:** Increased risk of lithium toxicity due to reduced renal clearance.
* **Antidiabetic Agents:** May diminish their effect.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium), renal function (BUN, creatinine), and fluid status (weight, I&O) at baseline and regularly during therapy.
* Blood pressure.
* Hearing (especially with high doses or risk factors for ototoxicity).
* Blood glucose and uric acid levels in susceptible patients.
## Clinical Pearls
* Administer oral furosemide preferably in the morning to minimize nocturia.
* If given intravenously, infuse slowly to reduce the risk of ototoxicity.
* Monitor for signs of dehydration and electrolyte imbalances.
* Accompanying potassium or magnesium supplementation may be necessary.
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**Disclaimer:** This information is intended for clinical pharmacists and healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines for complete details and to ensure patient-specific appropriateness of care.
