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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) caused by heart failure, liver disease, or kidney disease, and to treat high blood pressure.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:**
* Oral: 20 mg to 80 mg once daily. If ineffective, dose may be increased by 20 mg to 40 mg every 6 to 8 hours. Usual maintenance dose: 40 mg to 120 mg daily in divided doses. Maximum daily dose: 600 mg.
* Intravenous/Intramuscular: 20 mg to 40 mg once daily. If inadequate response, dose may be increased by 20 mg every 2 hours. Usual maintenance dose: 40 mg to 120 mg daily in divided doses. Maximum daily dose: 600 mg.
* **Hypertension:**
* Oral: 40 mg twice daily. Not recommended as the sole agent for hypertension.
## Pediatric Dosing
* **Edema:**
* Oral: 1 mg/kg/dose once daily, not to exceed 6 mg/kg/day.
* Intravenous/Intramuscular: 1 mg/kg/dose once daily, not to exceed 6 mg/kg/day.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in renal impairment due to reduced efficacy. However, caution is advised as high doses can lead to ototoxicity.
* **Hepatic Impairment:** Caution and dose reduction may be necessary due to increased sensitivity and risk of hepatic coma.
## Contraindications
* Anuria.
* History of hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* Electrolyte imbalance (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia).
* Dehydration.
* Ototoxicity (hearing loss, tinnitus), especially with rapid IV administration or high doses.
* Hypotension.
* Hyperuricemia, hyperglycemia.
* Dizziness, lightheadedness.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic drugs:** Increased risk of ototoxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effects.
* **Lithium:** Furosemide can decrease lithium clearance, increasing lithium toxicity risk.
* **Digoxin:** Risk of digoxin toxicity if hypokalemia develops.
* **Antihypertensives:** Additive hypotensive effect.
## Monitoring
* Electrolytes (serum potassium, sodium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or rapid IV administration)
## Clinical Pearls
* Administer IV furosemide slowly (over 30-60 minutes) to reduce the risk of ototoxicity. Rapid injection can cause profound diuresis and hypotension.
* Monitor for signs and symptoms of electrolyte imbalance, especially hypokalemia.
* Patients with heart failure may require lower doses of furosemide compared to those with renal disease.
* In infants, particularly premature infants, furosemide can increase the risk of nephrocalcinosis and nephrolithiasis; ultrasound monitoring may be considered.
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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 individual patient factors before making any treatment decisions.
