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## Furosemide (Lasix)
### Overview
Furosemide is a potent loop diuretic used to manage fluid overload and edema.
### Primary Indications
* Edema associated with congestive heart failure (CHF)
* Liver cirrhosis
* Renal disease (including nephrotic syndrome)
* Hypertension (usually as adjunctive therapy)
### Adult Dosing
* **Edema:**
* Oral: Start with 20-80 mg once daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. Usual maintenance dose: 20-120 mg/day, may be given as a single dose or divided. Maximum daily dose typically 600 mg, but higher doses have been used in refractory cases under close monitoring.
* Intravenous (IV)/Intramuscular (IM): Start with 20-40 mg once daily. Doses may be increased by 20 mg every 2 hours as needed. Usual maintenance dose: 20-120 mg/day. Maximum IV/IM dose typically 600 mg/day, but higher doses may be required.
* **Hypertension:** 40 mg twice daily. Not a first-line agent.
### Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once daily. Doses may be increased by 1 mg/kg every 6-8 hours as needed. Maximum dose: 6 mg/kg/day.
* IV/IM: 1 mg/kg/dose once daily. Doses may be increased by 1 mg/kg every 2 hours as needed. Maximum dose: 6 mg/kg/day. For neonatal intensive care unit (NICU) patients, lower initial doses (e.g., 0.5-1 mg/kg/dose) may be preferred.
### Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to decreased renal excretion, but monitor closely for ototoxicity. IV doses may be more effective than oral doses in severe renal dysfunction.
* **Hepatic Impairment:** Caution and reduced doses may be necessary.
### Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur)
* Hepatic coma or severe electrolyte depletion
### Adverse Effects
* **Common:** Dizziness, lightheadedness, muscle cramps, weakness, headache, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration.
* **Serious:** Ototoxicity (especially with rapid IV administration or high doses, reversible or irreversible), hypotension, hyperglycemia, hyperuricemia (gout), pancreatitis, Stevens-Johnson syndrome, aplastic anemia.
### Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May decrease diuretic and antihypertensive effect.
* **Lithium:** Reduced renal clearance, increased risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Potassium-depleting agents (e.g., corticosteroids):** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
### Monitoring
* **Electrolytes:** Sodium, potassium, chloride, magnesium, calcium (frequently, especially at initiation and with dose changes).
* **Renal function:** BUN, creatinine.
* **Blood pressure:** Monitor for hypotension.
* **Urine output:** Assess effectiveness and hydration status.
* **Hearing:** Assess for tinnitus or hearing loss.
* **Blood glucose:** In diabetic patients.
* **Uric acid:** In patients with a history of gout.
### Clinical Pearls
* Administer IV furosemide slowly (over at least 30-60 minutes) to minimize ototoxicity risk. Rapid IV push can lead to transient hearing loss.
* Oral administration is generally preferred for chronic management.
* Hypokalemia is a significant concern; consider potassium supplementation or potassium-sparing diuretics if clinically indicated.
* Monitor weight daily for patients with edema to assess fluid status.
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*Disclaimer: This information is intended for clinical professionals and does not substitute for professional judgment. Always consult the most current prescribing information and institutional protocols before making treatment decisions.*
