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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) associated with heart failure, liver disease, and kidney disease, as well as hypertension.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, or renal disease.
* Hypertension (often as add-on therapy).
## Adult Dosing
* **Edema:** 20 mg to 80 mg orally once daily. May be increased by 20 mg to 40 mg every 6-8 hours as needed. Maximum oral dose is typically 600 mg daily, but higher doses may be used in rare, select cases under close supervision. For rapid diuresis, IV administration may be preferred.
* **Hypertension:** 40 mg orally once daily. Doses may be adjusted based on response. Furosemide is generally not a first-line agent for hypertension unless edema is also present.
* **IV/IM Dosing:** 20 mg to 40 mg intravenously or intramuscularly once. May be repeated every 2 hours as needed. Higher doses may be administered in critical care settings.
## Pediatric Dosing
* **Edema/Hypertension:** 1 mg/kg/dose orally every 6-12 hours. Maximum single dose: 40 mg.
* **IV/IM Dosing:** 1 mg/kg/dose intravenously or intramuscularly every 6-12 hours. Maximum single dose: 40 mg.
## Dose Adjustments
* **Renal Impairment:** Higher doses may be required due to reduced efficacy. Closely monitor fluid status and electrolytes.
* **Hepatic Impairment:** Dose reduction may be necessary due to altered metabolism and increased risk of electrolyte disturbances.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur).
* Severe electrolyte depletion (e.g., hyponatremia, hypokalemia).
## Adverse Effects
* **Electrolyte Imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and Hypotension:** Especially with aggressive diuresis.
* **Ototoxicity:** Particularly with rapid IV administration or high doses.
* **Hyperglycemia and Hyperuricemia.**
* **Photosensitivity.**
* **Dizziness, headache, weakness.**
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced renal clearance of lithium, increasing the risk of lithium toxicity.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium) regularly, especially during initiation and dose changes.
* Fluid balance (intake and output).
* Weight (daily).
* Blood pressure.
* Renal function (BUN, creatinine).
* Blood glucose (in diabetic patients).
* Uric acid (in patients with gout).
* Hearing (if ototoxicity is suspected).
## Clinical Pearls
* Furosemide is a potent diuretic; initiate at the lowest effective dose.
* Oral administration is generally preferred for chronic conditions; IV administration is used for acute or severe fluid overload.
* Due to rapid onset and short duration of action, dosing frequency is critical for managing edema. Doses are often given once daily in the morning to minimize nocturia.
* For patients with significant renal impairment, continuous infusion or frequent high doses may be necessary.
* Monitor for signs and symptoms of dehydration and electrolyte imbalances.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and a qualified healthcare provider for any questions regarding a medication.*
