Please check your internet connection and try again.
# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium and chloride in the ascending limb of the loop of Henle. This leads to increased excretion of water, sodium, chloride, potassium, calcium, and magnesium.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with liver cirrhosis
* Edema associated with renal disease, including the nephrotic syndrome
* Hypertension (less commonly used as first-line therapy)
## Adult Dosing
* **Edema:** The usual starting dose is 20-80 mg orally once or twice daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. The maintenance dose varies widely. Intravenous (IV) or intramuscular (IM) doses are typically half the oral dose.
* Maximum oral dose: Generally 600 mg/day, but higher doses may be used cautiously in specific situations under close monitoring.
* Maximum IV/IM dose: Generally 200 mg in a single dose, but higher doses may be used cautiously under close monitoring.
* **Hypertension:** 40 mg orally once or twice daily. This indication is less common.
## Pediatric Dosing
* **Edema:**
* Oral: 1-4 mg/kg/dose once or twice daily. Maximum dose: 40 mg/day.
* IV/IM: 1 mg/kg/dose. Maximum dose: 20 mg/dose for infants and children younger than 12 years. Higher doses may be necessary in premature infants or children with severe renal impairment, but require careful monitoring.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal insufficiency due to reduced bioavailability and increased tubular secretion. However, higher doses are associated with increased risk of ototoxicity.
* **Hepatic Impairment:** Caution is advised. Monitor electrolytes and fluid status closely.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* **Electrolyte Imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and Hypotension:** Especially with rapid diuresis or excessive doses.
* **Ototoxicity:** Tinnitus, hearing impairment (often reversible, but can be permanent with high doses or rapid IV administration).
* **Hyperglycemia**
* **Hyperuricemia** (can precipitate gout)
* **Dizziness, lightheadedness**
* **Rash, photosensitivity**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Antihypertensives (including ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effects; increased risk of renal impairment.
* **Lithium:** Reduced renal clearance of lithium, increasing risk of lithium toxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* **Electrolytes:** Serum potassium, sodium, chloride, magnesium, and calcium.
* **Renal Function:** BUN, serum creatinine.
* **Fluid Status:** Daily weights, intake and output.
* **Blood Pressure:** Especially with initiation or dose adjustments.
* **Hearing:** Assess for tinnitus or hearing loss.
* **Blood Glucose:** In diabetic patients.
* **Uric Acid:** In patients prone to gout.
## Clinical Pearls
* Furosemide can be administered orally, IM, or IV. IV administration generally results in faster onset of diuresis.
* Rapid IV administration can increase the risk of ototoxicity. Administer IV furosemide slowly (e.g., over 30-60 minutes).
* If oral administration is not feasible or rapid diuresis is required, IM injection is an option.
* Continuous IV infusion may be more effective and safer than bolus injections in some cases of severe volume overload, but requires careful monitoring.
* Consider potassium supplementation or a potassium-sparing diuretic if hypokalemia is significant or persistent.
* Dosing for specific patient populations (e.g., neonates, critically ill) may depend on institutional protocols.
---
*This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any treatment decisions.*
