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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to reduce fluid overload (edema) associated with heart failure, liver disease, and kidney disease, including nephrotic syndrome. It is also used to manage hypertension.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, and renal disease
* Hypertension (adjunctive therapy)
## Adult Dosing
* **Edema:**
* Oral: Initial dose of 20-80 mg once daily. May increase by 20-40 mg every 6-8 hours as needed. Usual maintenance dose is 20-80 mg daily, but may be divided. Maximum daily dose is typically 600 mg.
* Intravenous (IV) or Intramuscular (IM): Initial dose of 20-40 mg once daily. May increase by 20 mg every 2 hours as needed. Usual maintenance dose is 20-80 mg daily, but may be divided. Maximum daily dose is typically 600 mg. Higher doses may be used in severe cases under close monitoring.
* **Hypertension:**
* Oral: 40 mg twice daily. Doses higher than 40 mg twice daily are not typically recommended for primary antihypertensive therapy.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once daily. If inadequate response, may increase dose by 1-2 mg/kg/dose every 6-8 hours. Do not exceed 6 mg/kg/dose.
* IV or IM: 1 mg/kg/dose once daily. If inadequate response, may increase dose by 1 mg/kg/dose every 2 hours. Do not exceed 6 mg/kg/dose.
* **Neonates:**
* IV or IM: 0.5-1 mg/kg/dose every 12-24 hours. Higher doses may be needed.
* **Hypertension:** Dosing in children for hypertension is not well established.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased, but monitor for toxicity. In severe renal impairment, response may be blunted.
* **Hepatic Impairment:** Use with caution.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides
## Adverse Effects
Common: Dizziness, lightheadedness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, hyperuricemia, hyperglycemia.
Serious: Severe electrolyte depletion, ototoxicity (especially with rapid IV administration or high doses), pancreatitis, aplastic anemia, Stevens-Johnson syndrome.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Lithium:** Furosemide can decrease lithium clearance, increasing risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride)
* BUN, creatinine
* Blood pressure
* Fluid intake and output
* Weight (for fluid status)
* Blood glucose (especially in diabetics)
* Uric acid
## Clinical Pearls
* Furosemide has a rapid onset of action, especially when given IV (within 5 minutes).
* To minimize nocturia, administer the last dose at least 4-6 hours before bedtime.
* Monitor closely for signs of dehydration and electrolyte imbalances, particularly hypokalemia. Potassium supplementation may be required.
* In patients with severe renal impairment, higher doses may be necessary, but efficacy can be reduced. Consider continuous infusion in some cases.
* Caution in patients with sulfa allergies; while cross-reactivity is possible, it is not absolute.
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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 ensure patient-specific appropriateness.*
