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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) and high blood pressure.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease.
* Hypertension (usually as adjunctive therapy).
## Adult Dosing
* **Edema:**
* Oral: Initial dose 20-80 mg once daily. Dose can be increased by 20-40 mg every 6-8 hours as needed.
* IV/IM: Initial dose 20-40 mg once daily. Dose can be increased by 20 mg every 2 hours as needed, or by 1-2 mg/kg/dose for severe cases.
* Maximum daily oral dose generally 600 mg, but may be higher in severe renal impairment.
* Maximum IV/IM dose generally 200 mg per dose, but may be higher under specialist supervision.
* **Hypertension:**
* Oral: 40 mg twice daily. Often used in combination with other antihypertensives.
* Maximum daily oral dose generally 600 mg.
## Pediatric Dosing
Dosing is highly variable and depends on indication and renal function. Consult specific pediatric guidelines or institutional protocols.
* **Edema:**
* Oral: 1-2 mg/kg/dose every 6-12 hours. Maximum 6 mg/kg/day.
* IV/IM: 1 mg/kg/dose every 6-12 hours. Maximum 6 mg/kg/day. Continuous infusions may be used: 0.1-0.4 mg/kg/hour.
## Dose Adjustments
* **Renal Impairment:** May require higher doses to achieve diuresis. Careful monitoring is essential.
* **Hepatic Impairment:** Use with caution; fluid and electrolyte balance is crucial.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Electrolyte Imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypocalcemia, hypomagnesemia.
* **Dehydration:** Dizziness, orthostatic hypotension.
* **Ototoxicity:** Hearing loss (usually reversible), tinnitus, particularly with rapid IV administration or high doses.
* **Metabolic:** Hyperglycemia, hyperuricemia (gout).
* **Renal:** Increased BUN and creatinine.
* **Other:** Rash, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects.
* **Lithium:** Increased risk of lithium toxicity due to reduced renal clearance.
* **Antihypertensives:** Additive hypotensive effects.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity, especially with hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Fluid balance (intake/output, daily weight).
* Blood pressure.
* Hearing (especially with high doses or IV administration).
## Clinical Pearls
* Administer oral furosemide on an empty stomach for better absorption, but can be given with food or milk if GI upset occurs.
* IV administration should be slow (over 30-60 minutes) to minimize ototoxicity. Avoid rapid infusion.
* Monitor for signs of hypokalemia (muscle cramps, weakness, arrhythmias). Potassium supplementation may be necessary.
* Furosemide can cause significant fluid and electrolyte losses. Assess patient's hydration status closely.
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***Disclaimer:** This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines before making treatment decisions.*
