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## Furosemide (Lasix)
### Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium and chloride in the thick ascending limb of the Loop of Henle, leading to increased excretion of water, sodium, chloride, potassium, calcium, and magnesium.
### Primary Indications
* Edema associated with congestive heart failure (CHF)
* Hepatic cirrhosis
* Renal disease (including nephrotic syndrome)
* Hypertension (adjunctive therapy)
### Adult Dosing
* **Edema:**
* Oral: 20-80 mg once daily. May increase by 20-40 mg every 6-8 hours as needed. Maximum daily dose typically 600 mg, but higher doses may be used in resistant cases under close supervision.
* Intravenous (IV) or Intramuscular (IM): 20-40 mg once daily. May increase by 20 mg every 2 hours as needed. Higher doses may be administered by continuous infusion or intermittent boluses.
* **Hypertension:**
* Oral: 40 mg twice daily. Not a first-line agent for uncomplicated hypertension.
### Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once daily. If inadequate response, may increase dose every 6 hours. Maximum dose 6 mg/kg/day.
* IV: 1 mg/kg/dose. If inadequate response, may increase dose every 2 hours. Maximum dose 6 mg/kg/day.
### Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to decreased drug clearance and increased volume of distribution. IV doses may be more effective than oral.
* **Hepatic Impairment:** Use with caution; may precipitate hepatic coma. Lower doses may be necessary.
### Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
### Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)
* Dehydration
* Hypotension
* Ototoxicity (especially with rapid IV administration or high doses)
* Hyperuricemia (may precipitate gout)
* Hyperglycemia
* Photosensitivity
* Rash
### Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Antihypertensives:** Additive hypotensive effects.
* **NSAIDs:** May reduce diuretic and antihypertensive efficacy.
* **Potassium-depleting agents (e.g., corticosteroids):** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced lithium clearance, increasing risk of lithium toxicity.
### Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or prolonged therapy)
* Blood glucose (in diabetic patients)
* Uric acid levels
### Clinical Pearls
* Oral administration is generally preferred for chronic conditions.
* IV administration is indicated for more rapid onset of diuresis or when oral absorption is impaired.
* The timing of administration can impact patient comfort due to nocturia.
* Monitor for signs and symptoms of electrolyte depletion, particularly hypokalemia. Potassium supplementation may be necessary.
* Rapid IV infusion (>4 mg/min) should be avoided to minimize the risk of ototoxicity.
* Use cautiously in patients with bladder outlet obstruction due to the risk of acute urinary retention.
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*Disclaimer: This information is intended for healthcare professionals and should not be a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any treatment decisions. Drug information can change, and it is crucial to verify the accuracy and completeness of the information provided.*
