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# Furosemide
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload (edema) associated with heart failure, liver disease, and kidney disease, as well as hypertension.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, or renal disease.
* Hypertension.
## Adult Dosing
* **Edema:**
* Oral: Start with 20-80 mg once daily. The dose may be increased by 20-40 mg every 6-8 hours as needed.
* Intravenous (IV) or Intramuscular (IM): Start with 20-40 mg once daily. The dose may be increased by 20 mg every 2 hours as needed.
* Continuous IV infusion: Initial dose of 4 mg/min for the first 1-2 hours, followed by an infusion of 2-4 mg/min.
* **Hypertension:**
* Oral: Start with 40 mg twice daily.
* **Maximum Doses:**
* Oral: 600 mg per day (higher doses may be used in severe edema under close supervision).
* IV/IM: Typically 80 mg per day, but higher doses may be used in hospitalized patients with severe edema.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once or twice daily. Maximum: 6 mg/kg/day.
* IV/IM: 1 mg/kg/dose once. If inadequate response, may increase by 1 mg/kg every 2 hours. Maximum: 6 mg/kg/day.
* *Note: Dosing for neonates and infants may vary; consult specific pediatric guidelines.*
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased due to decreased renal clearance. However, monitor for ototoxicity and nephrotoxicity.
* **Hepatic Impairment:** May require dose adjustment due to altered metabolism and distribution.
## Contraindications
* Anuria.
* 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).
* **Hyperglycemia.**
* **Hyperuricemia** (can precipitate gout).
* **Dizziness, lightheadedness.**
* **Rash, photosensitivity.**
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **ACE inhibitors, ARBs, other antihypertensives:** Additive hypotensive effects.
* **NSAIDs:** May decrease diuretic and antihypertensive effects, and increase risk of renal impairment.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Decreased renal clearance of lithium, increasing risk of lithium toxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* **Electrolytes:** Serum electrolytes (sodium, potassium, chloride, magnesium, calcium) and BUN/creatinine at baseline and regularly during therapy.
* **Fluid status:** Weight, intake/output, signs of edema.
* **Blood pressure:** Especially when used for hypertension or with other antihypertensives.
* **Hearing:** Assess for tinnitus or hearing loss.
## Clinical Pearls
* Administer IV furosemide slowly to minimize ototoxicity risk.
* Oral and IV doses are not necessarily interchangeable; oral bioavailability is about 50-60%.
* Concurrent potassium or magnesium supplementation may be necessary.
* Monitor closely for signs of dehydration and electrolyte abnormalities, especially in the elderly and those with significant renal or hepatic impairment.
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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 to determine the best course of treatment for your specific condition. Verify current prescribing information with the manufacturer's product insert or other reliable sources.
