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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 (CHF), cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:**
* Initial: 20-80 mg orally once or twice daily.
* Maintenance: 20-40 mg orally once or twice daily. Doses may be increased by 20-40 mg every 6-8 hours as needed.
* Maximum oral dose: 600 mg daily (higher doses may be used in severe cases under close supervision, typically in the hospital setting).
* **Hypertension:**
* Initial: 40 mg orally once daily.
* Maintenance: 20-40 mg orally once or twice daily.
* Maximum oral dose: 600 mg daily.
* **Intravenous (IV) or Intramuscular (IM):**
* Initial: 20-40 mg IV/IM once.
* Subsequent doses: 20-40 mg IV/IM every 6-8 hours as needed.
* Higher doses may be required in patients with severe renal impairment or significant fluid overload.
* Maximum IV/IM dose: Generally 200 mg in a single dose, but may be higher in specific situations (e.g., continuous infusion for severe edema).
## Pediatric Dosing
* **Edema:**
* Oral: 1-4 mg/kg/dose orally once or twice daily.
* IV/IM: 1 mg/kg/dose IV/IM once. Doses may be increased by 1 mg/kg/dose every 6-8 hours as needed.
* Maximum oral dose: 40 mg/day.
* Maximum IV/IM dose: 40 mg/dose.
* **Hypertension:** Dosing is not well established in pediatrics.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to reduced renal excretion and increased half-life. However, monitor closely for electrolyte imbalances and ototoxicity.
* **Hepatic Impairment:** Dose may need to be reduced due to increased bioavailability and prolonged half-life. Monitor for hepatic encephalopathy.
## Contraindications
* Anuria.
* Hypersensitivity to furosemide or sulfonamides.
* Electrolyte depletion (e.g., severe hypokalemia, hyponatremia).
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, hyperuricemia.
* **Serious:** Ototoxicity (hearing loss, tinnitus), severe allergic reactions, Stevens-Johnson syndrome, aplastic anemia, pancreatitis, hyperglycemia.
## Key Drug Interactions
* **Aminoglycosides, Cisplatin:** Increased risk of ototoxicity.
* **ACE Inhibitors, ARBs, Potassium-Sparing Diuretics:** Increased risk of hyperkalemia.
* **Corticosteroids, Other Diuretics:** Increased risk of hypokalemia.
* **Lithium:** Reduced renal clearance of lithium, leading to lithium toxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects and increase risk of renal impairment.
* **Digoxin:** Increased risk of digoxin toxicity due to hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride) and bicarbonate.
* Renal function (BUN, creatinine).
* Fluid status (weight, intake/output).
* Blood pressure.
* Hearing and tinnitus (especially with high doses or in patients with risk factors).
* Blood glucose (in diabetic patients).
* Uric acid.
## Clinical Pearls
* Administer oral doses with food or milk to minimize GI upset.
* Administer IV furosemide slowly to reduce the risk of ototoxicity. Rapid IV administration has been associated with hearing loss.
* Monitor urine output closely, as it is an indicator of efficacy.
* Edematous patients with impaired renal function may require higher doses.
* Be aware of the potential for paradoxical worsening of edema or ascites in patients with cirrhosis.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before use.*
