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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to treat hypertension, alone or in combination with other antihypertensives.
## Primary Indications
* Edema (heart failure, liver cirrhosis, 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. Usual dose range is 40 mg to 200 mg daily. Maximum single dose is 200 mg. Maximum daily dose is 600 mg.
* Intravenous (IV) or Intramuscular (IM): 20 mg to 40 mg once daily. Doses may be increased by 20 mg every 2 hours. Usual dose range is 40 mg to 200 mg daily. Maximum daily dose is 600 mg.
* **Hypertension:**
* Oral: 40 mg twice daily. Doses may be adjusted as needed. Not recommended as a first-line agent for hypertension unless edema is also present.
## Pediatric Dosing
* **Edema:**
* Oral: 1 mg/kg to 4 mg/kg per dose once or twice daily. Maximum dose is 40 mg once daily.
* IV or IM: 1 mg/kg per dose once daily. Maximum dose is 20 mg once daily. Doses can be increased to 2 mg/kg per dose once daily if needed.
## Dose Adjustments
* **Renal Impairment:** Use with caution and may require higher doses. Monitor electrolytes closely.
* **Hepatic Impairment:** May require dose reduction due to increased bioavailability. Monitor electrolytes closely.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)
* Dehydration
* Ototoxicity (hearing loss, tinnitus), especially with rapid IV administration or high doses.
* Hypotension
* Hyperuricemia (may precipitate gout)
* Hyperglycemia
* Photosensitivity
* Aplastic anemia, thrombocytopenia, agranulocytosis (rare)
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **Potassium-depleting drugs (e.g., corticosteroids):** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal clearance.
* **Antihypertensives:** Additive hypotensive effect.
## Monitoring
* Electrolytes (serum sodium, potassium, chloride, magnesium, calcium)
* BUN, creatinine
* Blood pressure
* Fluid intake and output
* Hearing (especially with high doses or IV administration)
* Blood glucose (in diabetic patients)
* Uric acid (in patients prone to gout)
## Clinical Pearls
* Administer IV furosemide slowly to avoid ototoxicity. A rate of 4 mg/minute or less is recommended for doses up to 40 mg. For doses greater than 40 mg, consider continuous infusion.
* Oral administration is generally preferred for chronic therapy.
* Furosemide can cause significant fluid and electrolyte losses; monitor patients closely, especially the elderly and those with significant comorbidities.
* If a patient is not responding to oral furosemide, consider an IV or IM formulation.
* The timing of furosemide doses should be considered to minimize nocturia and sleep disruption.
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*Please verify the current prescribing information and local protocols for definitive patient management.*
