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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. It is also used to manage high blood pressure, often in combination with other antihypertensives.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, and renal disease (including nephrotic syndrome).
* Hypertension (high blood pressure).
## Adult Dosing
* **Edema:**
* Starting dose: 20-80 mg orally once daily.
* Subsequent doses: May be increased by 20-40 mg every 6-8 hours as needed, or doses adjusted based on diuretic response.
* Maximum daily dose: Generally 600 mg orally, but higher doses may be used under close medical supervision in hospitalized patients.
* For patients requiring chronic oral therapy, doses are usually given once or twice daily.
* **Hypertension:**
* Starting dose: 40 mg orally twice daily.
* Subsequent doses: May be adjusted based on blood pressure response.
* Maximum daily dose: Typically 160 mg orally.
* **Intravenous (IV) Dosing (for severe edema unresponsive to oral therapy):**
* Starting dose: 20-40 mg IV once.
* Subsequent doses: May be administered every 2-6 hours. Dosing is highly individualized and depends on the patient's response and fluid status.
* Continuous IV infusion: May be considered for patients with severe edema and renal impairment. Initial infusion rates can range from 4 mg/hour, titrating upwards based on response.
## Pediatric Dosing
* **Edema/Hypertension:**
* 0-17 years: 1-2 mg/kg orally once daily.
* Maximum single dose: 40 mg.
* Doses may be increased every 6-8 hours if response is inadequate.
* Maximum daily dose: 6 mg/kg/day orally.
* **Intravenous (IV) Dosing:**
* 0-17 years: 1 mg/kg IV once.
* Maximum single IV dose: 20 mg.
* Doses may be increased by 1 mg/kg every 2 hours if response is inadequate.
* Maximum daily IV dose: 6 mg/kg/day.
## Dose Adjustments
* **Renal Impairment:** In patients with severe renal impairment, lower doses may be required, and response should be carefully monitored. In some cases, higher doses or continuous infusions may be necessary to achieve diuresis.
* **Hepatic Impairment:** Monitor for electrolyte imbalances and hepatic encephalopathy. Doses may need to be adjusted cautiously.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or its sulfonamide derivatives.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, dehydration, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), hyperuricemia, hyperglycemia.
* **Serious:** Hypotension, ototoxicity (hearing loss, tinnitus, especially with rapid IV administration or high doses), severe electrolyte depletion, pancreatitis, aplastic anemia, Stevens-Johnson syndrome.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Other Ototoxic Drugs:** Increased risk of hearing damage.
* **ACE Inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **NSAIDs:** May decrease furosemide's diuretic and antihypertensive effects and increase the risk of renal impairment.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Lithium:** Reduced lithium clearance and increased risk of lithium toxicity.
## Monitoring
* **Electrolytes:** Serum potassium, sodium, chloride, magnesium, and calcium should be monitored regularly, especially during initiation, dose changes, or in patients with risk factors for depletion.
* **Renal Function:** Serum creatinine and BUN.
* **Fluid Balance:** Daily weights, intake and output.
* **Blood Pressure:** Monitor for hypotension.
* **Hearing:** Assess for tinnitus or hearing loss.
## Clinical Pearls
* Administer oral furosemide on an empty stomach to enhance absorption, but may be given with food or
