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# Furosemide
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) and high blood pressure. It works by inhibiting the reabsorption of sodium and chloride in the kidneys, leading to increased excretion of water and electrolytes.
## Primary Indications
* Edema associated with congestive heart failure (CHF), liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:**
* Oral: 20 mg to 80 mg once daily. Doses may be increased by 20 mg to 40 mg every 6 to 8 hours until desired response is achieved. Usual dose is 40 mg to 120 mg daily, but doses up to 600 mg daily have been used in severe cases.
* Intravenous (IV)/Intramuscular (IM): 20 mg to 40 mg once daily. Doses may be increased by 20 mg to 40 mg every 2 hours until desired response is achieved. Usual dose is 40 mg to 80 mg daily, but doses up to 200 mg may be given as a single dose in severe cases.
* **Hypertension:**
* Oral: 40 mg twice daily. Not typically a first-line agent for hypertension; used when edema is also present.
## Pediatric Dosing
* **Edema:**
* Oral: 1 mg/kg/dose to 2 mg/kg/dose every 6 to 12 hours. Maximum dose: 6 mg/kg/dose daily.
* IV/IM: 1 mg/kg/dose every 6 to 12 hours. Maximum dose: 6 mg/kg/dose daily.
* Neonates: May be more sensitive to effects and require lower doses; use with caution.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to reduced drug excretion and increased protein binding. However, monitor closely for ototoxicity.
* **Hepatic Impairment:** Use with caution.
## Contraindications
* Anuria.
* History of hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, hyperuricemia, hyperglycemia.
* **Serious:** Ototoxicity (hearing loss, tinnitus, especially with rapid IV administration or high doses), severe dehydration, hypovolemia, acute kidney injury, Stevens-Johnson syndrome.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects; increased risk of renal impairment.
* **Lithium:** Reduced renal clearance of lithium, increasing risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride).
* Renal function (BUN, creatinine).
* Blood pressure.
* Urine output.
* Hearing (especially with high doses or risk factors for ototoxicity).
* Blood glucose.
* Uric acid.
## Clinical Pearls
* Administer oral furosemide with or without food.
* Rapid IV administration (>4 mg/min) can increase the risk of ototoxicity. For doses >80 mg, consider continuous IV infusion.
* Monitor for signs of dehydration and electrolyte depletion.
* Dietary potassium supplementation or potassium-sparing diuretics may be necessary to prevent hypokalemia, especially with chronic use.
* Furosemide can cause photosensitivity; advise patients to use sun protection.
* In patients with significant edema, response may be blunted due to reduced absorption. Consider IV administration.
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*Disclaimer: This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the current prescribing information and a healthcare professional for complete and up-to-date drug details and treatment decisions.*
