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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver disease, and renal disease. It is also used to treat hypertension.
## Primary Indications
* Edema (congestive heart failure, cirrhosis, renal disease)
* Hypertension (often used in combination with other agents)
## Adult Dosing
* **Edema:** 20-80 mg orally once or twice daily. Doses up to 200 mg/day may be given in divided doses in severe cases.
* **Hypertension:** 40 mg orally twice daily.
* **Intravenous (IV) or Intramuscular (IM):** 20-40 mg once daily. Doses can be increased by 20 mg every 2 hours. Higher doses may be required for severe edema or anuria.
## Pediatric Dosing
* **Oral:** 1-2 mg/kg/dose every 6-12 hours. Maximum dose: 6 mg/kg/day.
* **IV/IM:** 1 mg/kg/dose every 6-12 hours. Maximum dose: 6 mg/kg/day. For premature infants, doses may be lower (0.5-1 mg/kg/dose).
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased due to decreased renal excretion. However, caution is advised as increased doses can also worsen renal function. For patients with impaired renal function, continuous infusion may be more effective than intermittent bolus doses.
* **Hepatic Impairment:** Use with caution; dose reduction may be necessary.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur)
* Severe electrolyte depletion (e.g., hypokalemia, hyponatremia)
## Adverse Effects
* **Electrolyte Imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and Hypotension:** Especially with rapid diuresis.
* **Ototoxicity:** Hearing loss, tinnitus (particularly with rapid IV administration or high doses).
* **Hyperglycemia:** May occur, especially in patients with diabetes.
* **Hyperuricemia:** May precipitate gout.
* **Photosensitivity.**
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **ACE inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May decrease the diuretic and antihypertensive effects of furosemide and increase the risk of renal impairment.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal clearance.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Fluid intake and output
* Weight
* Hearing (especially with high doses or IV administration)
## Clinical Pearls
* Administer oral doses with or without food.
* IV administration should be given slowly (e.g., over 30-60 minutes) to reduce the risk of ototoxicity.
* Monitor for signs and symptoms of dehydration and electrolyte imbalances.
* For patients with heart failure, titrate to symptom relief and avoid excessive diuresis, which can lead to renal compromise.
* When treating hypertension, furosemide is typically used in patients with edema or impaired renal function; it is not usually a first-line agent for uncomplicated hypertension.
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*Disclaimer: This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider and refer to the official prescribing information for the most up-to-date and complete drug details.*
