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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 (CHF), liver cirrhosis, and renal disease (including nephrotic syndrome).
* Hypertension, usually in combination with other antihypertensives.
* Acute pulmonary edema.
## Adult Dosing
* **Edema:**
* Oral: 20 mg to 80 mg once daily. May be increased by 20 mg to 40 mg every 6 to 8 hours as needed. Doses may be given once daily, twice daily, or divided.
* Intravenous (IV) or Intramuscular (IM): 20 mg to 40 mg once daily. May be increased by 20 mg every 2 hours, or by 40 mg every 4 hours as needed. Continuous IV infusion may be used.
* Maximum daily oral dose: 600 mg (higher doses may be used in severe cases under close monitoring).
* Maximum daily IV/IM dose: Generally 100 mg, but higher doses may be used in refractory cases under expert supervision.
* **Hypertension:**
* Oral: 40 mg twice daily.
* Adjunctive therapy: Typically 20 mg to 40 mg once or twice daily.
* **Acute Pulmonary Edema:**
* IV: 40 mg. If inadequate response after 1 hour, administer an additional 40 mg to 80 mg IV. Doses up to 200 mg have been reported in severe cases.
## Pediatric Dosing
Dosing is highly individualized and depends on the indication and patient's response. Consult specific pediatric guidelines or expert advice.
* **Edema/Hypertension:**
* Oral: 1 mg/kg to 2 mg/kg once daily, up to a maximum of 6 mg/kg/day.
* IV/IM: 1 mg/kg once daily, up to a maximum of 20 mg/dose. May increase by 1 mg/kg every 2 hours.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased due to decreased renal excretion and tubular secretion. Careful monitoring of response and electrolytes is essential.
* **Hepatic Impairment:** Dose may need to be reduced due to altered pharmacokinetics.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and hypotension.**
* **Ototoxicity** (especially with rapid IV administration or high doses).
* **Hyperuricemia** and gout.
* **Hyperglycemia.**
* **Dizziness, lightheadedness.**
* **Photosensitivity.**
* **Rash, pruritus.**
* **Tinnitus, hearing impairment.**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects, and increase risk of nephrotoxicity.
* **Lithium:** Furosemide can decrease renal clearance of lithium, increasing the risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Cisplatin:** Increased risk of ototoxicity and nephrotoxicity.
## Monitoring
* **Electrolytes:** Serum sodium, potassium, chloride, magnesium, calcium.
* **Renal function:** BUN, serum creatinine.
* **Fluid balance:** Intake and output, daily weight.
* **Blood pressure.**
* **Hearing function** (especially with high doses or risk factors for ototoxicity).
* **Blood glucose** in diabetic patients.
* **Uric acid levels.**
## Clinical Pearls
* Furosemide is a potent diuretic; monitor for signs of dehydration and electrolyte depletion.
* Administer IV furosemide slowly (e.g., over 30-60 minutes) to reduce the risk of ototoxicity. Avoid rapid IV push.
* For patients with significant edema or poor oral absorption, IV administration may be necessary.
* Oral dosing once daily in the morning is often preferred to minimize nocturia. However, twice-daily dosing may be needed for more consistent diuresis.
* Electrolyte replacement may be required, especially potassium.
* Monitor patients closely for hearing loss, particularly those receiving high doses or concomitant ototoxic drugs.
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**Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Always verify current prescribing information with the official product labeling or consult a healthcare professional before making any treatment decisions.
