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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to reduce fluid overload.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with hepatic cirrhosis
* Edema associated with renal disease, including the nephrotic syndrome
* Acute pulmonary edema
## Adult Dosing
* **Oral:**
* For edema: Start with 20-80 mg once daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. A typical maintenance dose is 40-80 mg once daily.
* For acute pulmonary edema: Initial dose of 20-40 mg orally may be given if IV administration is not immediately feasible.
* Maximum oral dose: Generally, 600 mg daily, but higher doses have been used cautiously under close medical supervision.
* **Intravenous (IV):**
* For edema: Start with 20-40 mg IV once daily. Doses may be increased by 20 mg every 6-8 hours as needed.
* For acute pulmonary edema: Initial dose of 40 mg IV. If response is inadequate after 1-2 hours, administer another 40 mg IV.
* Maximum IV dose: Generally, 200 mg in a single dose, but higher doses may be used cautiously in specific situations under close medical supervision. Continuous IV infusion may be considered for refractory edema.
## Pediatric Dosing
* **Oral:**
* 1-2 mg/kg once daily. If inadequate response, doses can be increased by 1-2 mg/kg every 6-8 hours.
* Maximum dose: 6 mg/kg/day.
* **Intravenous (IV):**
* 0.5-1 mg/kg once daily. If inadequate response, doses can be increased by 0.5-1 mg/kg every 2 hours.
* Maximum dose: 6 mg/kg/day.
## Dose Adjustments
* **Renal Impairment:** May require higher doses due to decreased renal excretion. Monitor closely for efficacy and toxicity.
* **Hepatic Impairment:** Use with caution; may precipitate hepatic coma. Dosing adjustments may be necessary.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration:** Especially in elderly patients.
* **Ototoxicity:** Usually reversible, risk increased with rapid IV administration, high doses, and in renal impairment.
* **Hyperglycemia:**
* **Hyperuricemia:** May precipitate gout.
* **Hypotension:**
* **Dizziness, lightheadedness:**
* **Rash, photosensitivity:**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May reduce the diuretic and antihypertensive effect of furosemide.
* **Potassium-sparing diuretics:** May reduce the risk of hypokalemia.
* **Succinylcholine:** May prolong neuromuscular blockade.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid balance (intake and output)
* Weight
* Blood pressure
* Auditory function, particularly with high doses or rapid IV administration.
## Clinical Pearls
* Administer oral furosemide in the morning to minimize nocturia.
* Rapid IV administration can increase the risk of ototoxicity. Infuse IV doses slowly over 30-60 minutes (unless in an acute emergency).
* Electrolyte repletion may be necessary, particularly potassium supplementation, depending on patient status and laboratory values.
* Patients with edema due to CHF may require chronic therapy.
* Monitor for signs and symptoms of dehydration and electrolyte abnormalities.
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*This information is intended for clinical decision-making and does not replace current prescribing information. Always verify with the most up-to-date product monograph and institutional protocols.*
