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 thick ascending limb of the loop of Henle, leading to a significant increase in urine output. It also reduces preload and afterload.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with hepatic cirrhosis
* Edema associated with renal disease (including the nephrotic syndrome)
* Management of hypertension (as adjunctive therapy)
## Adult Dosing
* **Edema:**
* **Oral:** Start with 20-80 mg once daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. Maximum daily oral dose is typically 600 mg, but higher doses have been used under close supervision. Doses greater than 80 mg are usually divided.
* **Intravenous (IV) or Intramuscular (IM):** Start with 20-40 mg once daily. If no response, administer 40 mg IV/IM. Subsequent doses can be increased by 20 mg at intervals of 2 hours or more. Maximum IV/IM dose is typically 200 mg in a single dose, but higher doses may be required in severe cases (e.g., pulmonary edema), up to 1000 mg/day under intensive monitoring.
* **Hypertension:**
* **Oral:** 40 mg twice daily. Typically used as add-on therapy.
## Pediatric Dosing
* **Edema:**
* **Oral:** 1-4 mg/kg/day divided every 6-12 hours. Maximum daily dose is 6 mg/kg.
* **IV or IM:** 1 mg/kg/dose every 6-12 hours. Maximum dose is 6 mg/kg/dose.
* *Note: Dosing can vary significantly based on clinical scenario and patient response. Consult specific pediatric guidelines or protocols.*
## Dose Adjustments
* **Renal Impairment:** May require higher doses due to impaired absorption and diuretic resistance. However, monitor closely for ototoxicity and electrolyte imbalances.
* **Hepatic Impairment:** Monitor for electrolyte imbalances and hepatic encephalopathy.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
* Severe electrolyte depletion (e.g., hypokalemia, hyponatremia)
* Hepatic coma or pre-coma
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), dehydration, hypotension, azotemia, hyperuricemia, hyperglycemia.
* **Less Common/Serious:** Ototoxicity (hearing loss, tinnitus, often irreversible with rapid IV administration or high doses), Stevens-Johnson syndrome, toxic epidermal necrolysis, aplastic anemia, pancreatitis, cholestatic jaundice, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides, Cisplatin:** Increased risk of ototoxicity.
* **Corticosteroids, ACTH:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to hypokalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effect, and increase risk of renal impairment.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal clearance.
* **Antihypertensives (e.g., ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Thiazide diuretics:** Additive diuretic effect.
## Monitoring
* **Electrolytes:** Sodium, potassium, chloride, magnesium, calcium.
* **Renal function:** BUN, creatinine.
* **Fluid balance:** Intake and output, daily weights.
* **Blood pressure:** Especially at initiation or dose change.
* **Hearing:** Audiometric testing may be considered in patients on long-term high-dose therapy.
* **Blood glucose:** In diabetic patients.
* **Uric acid:** In patients with history of gout.
## Clinical Pearls
* Oral administration can be less effective than IV/IM in patients with severe edema due to impaired GI absorption.
* Rapid IV administration (e.g., >20 mg/min) is associated with a higher risk of ototoxicity. Administer IV doses over 30-60 minutes unless in acute pulmonary edema.
* Patients with significant edema may require higher doses due to reduced absorption and increased volume of distribution.
* When switching from IV to oral therapy, the oral dose should generally be 1.5 to 2 times the effective IV dose.
* Continuous IV infusion may be more effective and less ototoxic than intermittent bolus doses in some patients with severe edema.
***
**Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always consult the most current prescribing information and professional medical judgment before making any treatment decisions. Local protocols may dictate specific dosing strategies and monitoring parameters.
