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# Furosemide (Lasix)
## Overview
Furosemide is a loop diuretic used to treat edema associated with heart failure, liver disease, and kidney disease, including the nephrotic syndrome. It is also used to treat hypertension, although it's not a first-line agent for this indication.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, and renal disease.
* Hypertension (adjunctive therapy).
## Adult Dosing
* **Edema:**
* Oral: 20-80 mg once daily, then adjust as needed. Doses higher than 80 mg should be given in divided doses. The usual maintenance dose is 40 mg once or twice daily.
* Intravenous (IV)/Intramuscular (IM): 20-40 mg once daily, then adjust as needed. For severe edema, doses of 80-120 mg may be given once, then followed by a continuous IV infusion of 10 mg/hour.
* **Hypertension:**
* Oral: 40 mg twice daily. Not typically used as monotherapy.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/day divided into 1-2 doses. Maximum dose: 6 mg/kg/day.
* IV/IM: 1 mg/kg/dose, not to exceed 20 mg/dose for a single dose. For patients unresponsive to lower doses, doses up to 6 mg/kg/dose may be administered.
## Dose Adjustments
* **Renal Impairment:** Dose adjustments may be necessary, particularly with IV administration. Patients with significant renal impairment may require higher doses.
* **Hepatic Impairment:** Monitor electrolytes and fluid status closely.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
* Severe electrolyte imbalance (e.g., hypokalemia, hyponatremia).
* Hepatic coma.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypocalcemia, hypomagnesemia.
* **Dehydration and hypotension.**
* **Ototoxicity:** Hearing impairment, tinnitus (especially with rapid IV administration or high doses).
* **Hyperglycemia.**
* **Hyperuricemia:** May precipitate gout.
* **Dizziness, lightheadedness.**
* **Rash, photosensitivity.**
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May decrease the diuretic and antihypertensive effect of furosemide and increase the risk of renal impairment.
* **Antihypertensives (including other diuretics):** Additive hypotensive effects.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal clearance.
* **Digoxin:** Increased risk of digoxin toxicity, especially if hypokalemia occurs.
* **Potassium supplements/Potassium-sparing diuretics:** May be used cautiously to manage hypokalemia but require close monitoring.
## Monitoring
* **Electrolytes:** Serum sodium, potassium, chloride, calcium, magnesium.
* **Renal function:** Serum creatinine, BUN.
* **Fluid status:** Weight, blood pressure, signs of edema.
* **Hearing:** Assess for tinnitus or hearing loss, especially with high doses or prolonged therapy.
* **Blood glucose and uric acid levels** in susceptible patients.
## Clinical Pearls
* Administer oral furosemide with or without food.
* If given for edema, administer in the morning to minimize nocturia.
* Rapid IV administration can increase the risk of ototoxicity. Administer IV doses slowly, usually over 30-60 minutes, or via continuous infusion.
* Monitor urine output closely; a significant decrease in urine output may indicate worsening renal function or insufficient dosing.
* Correct significant electrolyte imbalances before initiating therapy or monitor closely during treatment.
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*Disclaimer: 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 clinical guidelines for complete details and to verify information before making treatment decisions.*
