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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, as well as hypertension.
## Primary Indications
* Edema due to congestive heart failure, liver cirrhosis, or renal disease.
* Hypertension (adjunctive therapy).
## Adult Dosing
* **Edema:**
* **Initial:** 20-80 mg orally once daily. Doses may be given every 6-8 hours if needed.
* **Maintenance:** Adjust dose based on response. Doses up to 600 mg/day have been used in severe cases under close monitoring.
* **Intermittent therapy:** 40 mg orally daily, with a dose-free day every other day or 1-2 days per week.
* **Hypertension:** 40 mg orally twice daily. Typically used in combination with other antihypertensives.
* **Intravenous (IV)/Intramuscular (IM):**
* **Edema:** 20-40 mg IV/IM once daily. Doses can be increased by 20 mg every 2 hours if no response. Continuous IV infusion may be considered for severe edema.
* **Hypertensive emergencies:** 40-80 mg IV.
## Pediatric Dosing
* **Edema:**
* **Oral:** 1-2 mg/kg/dose orally once or twice daily. Maximum 6 mg/kg/day.
* **IV/IM:** 1 mg/kg/dose IV/IM once daily. Maximum 6 mg/kg/dose. Doses up to 4 mg/kg/day may be given in divided doses if needed.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in renal impairment due to decreased efficacy and prolonged half-life. Close monitoring of electrolytes and fluid status is crucial.
* **Hepatic Impairment:** Use with caution. Monitor for electrolyte imbalances and hepatic encephalopathy.
## Contraindications
* Anuria.
* History of hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalance (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), dehydration, orthostatic hypotension, hearing loss (especially with rapid IV administration or high doses), rash.
* **Less Common:** Hyperuricemia, hyperglycemia, pancreatitis, aplastic anemia, thrombocytopenia, Stevens-Johnson syndrome.
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May decrease diuretic and antihypertensive effects; increased risk of renal dysfunction.
* **ACE inhibitors/ARBs/DRIs:** Increased risk of hypotension and renal dysfunction.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to hypokalemia.
* **Lithium:** Increased risk of lithium toxicity; monitor lithium levels.
* **Antidiabetic agents:** May decrease efficacy.
## Monitoring
* **Electrolytes:** Serum electrolytes (sodium, potassium, chloride, magnesium, calcium) and bicarbonate.
* **Renal function:** BUN, creatinine.
* **Fluid balance:** Daily weights, intake and output.
* **Blood pressure:** Especially with parenteral administration or in hypertensive patients.
* **Hearing:** Audiometric testing if ototoxicity is suspected.
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize GI upset.
* Administer IV furosemide slowly (e.g., over 30-60 minutes) to reduce the risk of ototoxicity. Rapid IV administration can cause transient deafness.
* Monitor for signs of dehydration and electrolyte depletion (e.g., muscle cramps, confusion, arrhythmias).
* Potassium supplementation may be necessary, especially with prolonged use or higher doses.
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*This information is intended for healthcare professionals. Always verify current prescribing information and consult relevant guidelines before making clinical decisions.*
