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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium and chloride in the ascending limb of the loop of Henle, leading to increased excretion of water, sodium, potassium, chloride, calcium, and magnesium.
## Primary Indications
* Edema associated with congestive heart failure (CHF), liver cirrhosis, and renal disease (including the nephrotic syndrome).
* Hypertension (usually in combination with other antihypertensives).
* Acute pulmonary edema.
## Adult Dosing
* **Edema:** Initial dose is typically 20-80 mg orally once or twice daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. Doses can range from 20 mg to 600 mg daily, divided into 1-4 doses.
* **Hypertension:** Initial dose is typically 40 mg orally twice daily. Doses can range from 40-120 mg daily, divided into two doses.
* **Acute Pulmonary Edema:** 20-40 mg IV. If IV is not available, 40 mg orally. Doses may be repeated every 2 hours if needed.
## Pediatric Dosing
* **Edema/Hypertension:** 1-2 mg/kg orally once daily. Doses may be increased by 1-2 mg/kg every 6-8 hours as needed. Maximum oral dose is 6 mg/kg/day.
* **Acute Pulmonary Edema (IV):** 1 mg/kg/dose IV, not to exceed 20 mg/dose. Doses may be repeated every 2 hours.
## Dose Adjustments
* **Renal Impairment:** Dose adjustment may be necessary. In severe renal impairment, consider increasing the dose and duration of therapy, or administering IV doses more frequently.
* **Hepatic Impairment:** Use with caution due to risk of electrolyte imbalance and hepatic encephalopathy.
## Contraindications
* Anuria.
* History of hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration:** Dizziness, orthostatic hypotension.
* **Ototoxicity:** Tinnitus, hearing loss (especially with rapid IV administration or in patients with renal impairment).
* **Metabolic:** Hyperuricemia (may precipitate gout), hyperglycemia.
* **Renal:** Increased BUN and creatinine.
* **Hematologic:** Thrombocytopenia, leukopenia, anemia.
* **Dermatologic:** Rash, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **ACE Inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **NSAIDs:** May blunt the diuretic and antihypertensive effect of furosemide and increase the risk of renal dysfunction.
* **Lithium:** Furosemide can decrease lithium clearance, increasing the risk of lithium toxicity.
* **Potassium-Sparing Diuretics/Spironolactone/Eplerenone:** Risk of hyperkalemia.
* **Digoxin:** Furosemide-induced hypokalemia can increase digoxin toxicity.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Fluid status (weight, intake/output).
* Blood pressure.
* Hearing (especially with high doses or IV administration).
* Blood glucose and uric acid levels (particularly in patients with pre-existing conditions).
## Clinical Pearls
* Rapid IV administration can increase the risk of ototoxicity. Infuse IV furosemide slowly, typically over 30-60 minutes.
* Oral administration is usually slower to take effect but may provide a more sustained diuresis.
* Furosemide is a high-ceiling diuretic, meaning its diuretic effect increases with dose up to a ceiling.
* Monitor for signs of dehydration and electrolyte depletion, especially in elderly patients or those with significant fluid losses.
* Oral doses are typically given in the morning to minimize nocturia.
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*This information is intended for healthcare professionals and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any clinical decisions.*
