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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) due to heart failure, liver disease, and kidney disease, including nephrotic syndrome. It is also used to treat high blood pressure, alone or in combination with other antihypertensives.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:** 20 mg to 80 mg orally once daily. Doses may be increased by 20 mg to 40 mg every 6 to 8 hours as needed. The usual maintenance dose is 40 mg to 80 mg orally once daily.
* **Hypertension:** 40 mg orally twice daily.
* **Acute Edema:** 20 mg to 40 mg intravenously or intramuscularly once. If inadequate response, may increase by 20 mg to 40 mg every 2 hours.
* **Maximum Oral Dose:** Generally, no more than 600 mg per day should be used for prolonged periods in patients with chronic renal failure. Higher doses may be used in specific acute situations under close monitoring.
* **Maximum IV/IM Dose:** No specific maximum dose is established; doses are individualized based on response and patient condition.
## Pediatric Dosing
* **Edema:**
* Oral: 1 mg/kg to 2 mg/kg once daily. Doses may be increased by 1 mg/kg to 2 mg/kg every 6 to 8 hours as needed. Maximum dose is 6 mg/kg per day.
* IV/IM: 1 mg/kg once daily. If inadequate response, may increase by 1 mg/kg every 2 hours. Maximum dose is 6 mg/kg per day.
* **Hypertension:** Safety and efficacy in pediatric patients have not been established for this indication.
## Dose Adjustments
* **Renal Impairment:** Dosage may need to be increased due to reduced renal excretion. Close monitoring of fluid and electrolyte status is essential.
* **Hepatic Impairment:** Dosage may need to be reduced due to altered metabolism and increased sensitivity.
## Contraindications
* Anuria.
* History of hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia).
* Dehydration.
* Hypotension.
* Ototoxicity (hearing loss, tinnitus), especially with rapid IV administration or high doses.
* Hyperglycemia.
* Hyperuricemia (can precipitate gout).
* Photosensitivity.
* Aplastic anemia, agranulocytosis, thrombocytopenia (rare).
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects.
* **Lithium:** Furosemide can decrease lithium clearance, leading to increased lithium levels and toxicity.
* **Potassium-sparing Diuretics/ACE Inhibitors/ARBs/Spironolactone/Eplerenone:** Increased risk of hyperkalemia.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Risk of digoxin toxicity is increased with furosemide-induced hypokalemia.
* **Antihypertensives:** Additive hypotensive effects.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Fluid balance (intake and output, weight).
* Blood pressure.
* Blood glucose and uric acid levels (periodically).
* Hearing status.
## Clinical Pearls
* Administer oral furosemide in the morning to minimize nocturnal diuresis.
* Rapid IV administration can cause ototoxicity. Infuse slowly, typically over 30-60 minutes for doses up to 40 mg, or as an infusion for higher doses.
* Monitor for signs and symptoms of electrolyte depletion, particularly hypokalemia, which can increase the risk of cardiac arrhythmias.
* Furosemide can cause orthostatic hypotension. Advise patients to rise slowly from sitting or lying positions.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols for definitive guidance.*
