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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload and edema.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease (including nephrotic syndrome).
* Hypertension (alone or in combination with other antihypertensives).
* Acute pulmonary edema.
## Adult Dosing
* **Edema:**
* **Oral:** Start with 20-80 mg once daily. The dose may be titrated upwards by 20-40 mg every 6-8 hours or by 20-40 mg every day or every other day. The usual maintenance dose is 40-80 mg daily. Doses may be given in 1-2 divided doses.
* **Intravenous (IV) / Intramuscular (IM):** Start with 20-40 mg once daily. The dose may be titrated upwards by 20 mg every 2 hours.
* **Maximum daily dose:** Generally 600 mg, but higher doses may be necessary in severe cases under close medical supervision.
* **Hypertension:**
* **Oral:** Start with 40 mg twice daily. Adjust based on response.
* **Acute Pulmonary Edema:**
* **IV:** 40 mg administered as soon as possible. If response is inadequate after 2 hours, administer an additional 80 mg IV. Further doses should be guided by response.
## Pediatric Dosing
* **Edema:**
* **Oral:** 1-2 mg/kg/dose once daily. If inadequate response, doses may be repeated every 6 hours or increased. Maximum dose: 6 mg/kg/day.
* **IV/IM:** 1 mg/kg/dose once daily. If inadequate response, doses may be repeated every 2 hours. Maximum dose: 6 mg/kg/day.
* **Neonates:** Dosing varies significantly. Consultation with a pediatric specialist or reference is recommended. Typical starting doses are 0.5-1 mg/kg/dose every 12-24 hours.
## Dose Adjustments
* **Renal Impairment:** Dose adjustment is complex and requires careful monitoring. Higher doses may be needed in patients with impaired renal function.
* **Hepatic Impairment:** Monitor for electrolyte imbalances and fluid status closely.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
* Electrolyte depletion (e.g., hypokalemia, hyponatremia).
## Adverse Effects
* **Electrolyte Imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration:** Dizziness, orthostatic hypotension.
* **Ototoxicity:** Tinnitus, hearing loss (usually reversible, risk increased with rapid IV administration or high doses).
* **Metabolic:** Hyperuricemia, hyperglycemia.
* **Renal:** Increased BUN and creatinine.
* **Gastrointestinal:** Nausea, vomiting, diarrhea.
* **Dermatologic:** Rash, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **ACE Inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **Digoxin:** Risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced renal clearance of lithium, increasing the risk of lithium toxicity.
* **Corticosteroids/ACTH:** Increased risk of electrolyte depletion.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid balance (intake/output, weight)
* Blood pressure
* Hearing (especially with high doses or IV administration)
* Blood glucose and uric acid (in susceptible individuals)
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize gastrointestinal upset.
* IV administration should be slow (e.g., over 30-60 minutes) to reduce the risk of ototoxicity. Rapid IV injection can cause transient deafness.
* Monitor for signs of dehydration and electrolyte depletion.
* Dosing is highly individualized and depends on the severity of fluid overload and patient response.
* May require potassium supplementation if hypokalemia develops.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making therapeutic decisions. Local protocols may influence dosing and management.
