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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium, chloride, and potassium in the thick ascending limb of the Loop of Henle, leading to increased excretion of these electrolytes and water.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with liver cirrhosis
* Edema associated with renal disease, including nephrotic syndrome
* Hypertension (usually used as an adjunct)
* Acute pulmonary edema
## Adult Dosing
* **Edema:** Initial dose is typically 20-80 mg orally once daily. Doses can be increased by 20-40 mg every 6-8 hours as needed. The usual maintenance dose is 40-80 mg orally once daily or divided twice daily. Doses up to 600 mg/day have been used in severe edema under close medical supervision.
* **Hypertension:** 40 mg orally twice daily.
* **Acute Pulmonary Edema:** 20-40 mg intravenously. If inadequate response, may repeat dose every 2 hours. Higher IV doses may be required.
## Pediatric Dosing
* **Edema and Hypertension:** 1-2 mg/kg orally once daily. Maximum 6 mg/kg/day.
* **Intravenous:** 1 mg/kg once daily. If inadequate response, may increase to 2 mg/kg/day. Higher doses may be required under close supervision.
## Dose Adjustments
* **Renal Impairment:** Patients with renal impairment may require higher doses due to reduced renal clearance and altered protein binding. Dose titration should be guided by clinical response and electrolyte levels.
* **Hepatic Impairment:** Use with caution. Dose adjustments may be necessary.
## Contraindications
* Anuria
* History of hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)
* Dehydration
* Hypotension
* Ototoxicity (especially with rapid IV administration or high doses)
* Hyperuricemia, hyperglycemia
* Dizziness, lightheadedness
* Nausea, vomiting, diarrhea
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal clearance.
* **Antihypertensives:** Additive hypotensive effects.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or risk factors for ototoxicity)
* Blood glucose and uric acid levels
## Clinical Pearls
* Administer furosemide orally in the morning to minimize nocturia.
* IV administration can be given as a bolus or continuous infusion. Bolus doses should be administered slowly (e.g., over 1-2 minutes) to minimize ototoxicity risk.
* Monitor for signs and symptoms of dehydration and electrolyte imbalance.
* Potassium supplementation may be necessary, especially with prolonged use or higher doses.
* Effectiveness may be reduced in patients with significant edema due to decreased absorption. In such cases, IV administration is preferred.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for complete details and to verify this information.*
