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# Furosemide
## 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, either alone or in combination with other antihypertensives.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, renal disease, and nephrotic syndrome.
* Hypertension.
## Adult Dosing
* **Edema:**
* Oral: 20 mg to 80 mg once daily. The dose may be increased by 20 mg to 40 mg every 6 to 8 hours until the desired response is achieved. Doses up to 600 mg/day have been used in severe cases under close medical supervision.
* Intravenous (IV) or Intramuscular (IM): 20 mg to 40 mg once daily. If inadequate response, may increase dose or give at 6-8 hour intervals. Doses up to 200 mg in a single IV dose have been used in severe cases.
* **Hypertension:**
* Oral: 40 mg twice daily. Doses may be adjusted based on response. It is rarely used as a sole agent for hypertension.
## Pediatric Dosing
* **Edema:**
* Oral: 1 mg/kg/dose to 2 mg/kg/dose every 6 to 12 hours. Maximum dose is 6 mg/kg/day.
* IV/IM: 1 mg/kg/dose every 6 to 12 hours. Maximum dose is 6 mg/kg/day.
* **Neonates:** Due to immature renal function, doses may need to be lower and given less frequently. Consult specific neonatal protocols.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment due to decreased GFR and increased half-life. Close monitoring of response and electrolytes is essential. Doses are often guided by diuresis response rather than serum creatinine.
* **Hepatic Impairment:** May require dose reduction and close monitoring for electrolyte imbalances and hepatic encephalopathy.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, dehydration, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), hyperuricemia, hyperglycemia.
* **Serious:** Hypotension, ototoxicity (especially with rapid IV administration or high doses), severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis), blood dyscrasias, pancreatitis, rhabdomyolysis.
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce the diuretic and natriuretic effect.
* **Lithium:** Increased risk of lithium toxicity.
* **Antihypertensives (e.g., ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Blood glucose (in diabetic patients)
* Uric acid
* Hearing (especially with high doses or IV administration)
## Clinical Pearls
* Administer oral furosemide on an empty stomach to increase absorption, but may be taken with food or milk if gastric upset occurs.
* IV administration is generally more potent and has a faster onset of action than oral. Rapid IV infusion can increase the risk of ototoxicity. Slow infusion (e.g., over 20-30 minutes) is preferred.
* Continuous IV infusion may be more effective than intermittent bolus doses in critically ill patients with severe edema.
* Electrolyte replacement, particularly potassium, may be necessary with continued use.
* Monitor for signs of dehydration and electrolyte imbalance.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the official prescribing information and relevant guidelines for the most current and complete drug details. Local protocols may dictate specific dosing adjustments.
