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# Furosemide
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload and edema, as well as hypertension.
## Primary Indications
* Edema associated with congestive heart failure (CHF), liver cirrhosis, and renal disease (including nephrotic syndrome).
* Hypertension (essential hypertension), usually in combination with other antihypertensives.
* Management of acute and chronic renal failure.
## Adult Dosing
**Edema:**
* **Oral:**
* Initial dose: 20-80 mg once daily.
* Dose may be adjusted by 20-40 mg every 6-8 hours as needed.
* For chronic edema, the dose may be administered every day or every other day.
* Maximum daily dose: 600 mg.
* **Intravenous (IV) or Intramuscular (IM):**
* Initial dose: 20-40 mg once daily.
* If inadequate response, doses may be increased by 20 mg every 2 hours.
* Continuous IV infusion: Start at 4 mg/hour after an initial IV bolus of 20-40 mg.
* Maximum IV dose: Generally 40 mg initially, but higher doses may be required in severe edema. Doses up to 100-200 mg IV have been used, but require careful monitoring.
**Hypertension:**
* **Oral:**
* Initial dose: 40 mg twice daily.
* May be adjusted to 20-60 mg twice daily.
* Maximum daily dose: 120 mg, but higher doses are not typically recommended for hypertension alone.
**Acute Renal Failure:**
* **Oral:** 100 mg once daily.
* **IV:** 100-200 mg once daily.
## Pediatric Dosing
**Edema:**
* **Oral:** 1-2 mg/kg/dose once daily, not to exceed 6 mg/kg/day.
* **IV or IM:** 1 mg/kg/dose once daily, not to exceed 6 mg/kg/day. Doses may be repeated every 6-8 hours if needed.
**Neonates (especially premature):**
* **Oral:** 1 mg/kg/dose every 12-24 hours.
* **IV or IM:** 0.5-1 mg/kg/dose every 12-24 hours.
## Dose Adjustments
* **Renal Impairment:** In patients with severe renal impairment, larger and more frequent doses may be needed to achieve the desired diuresis. Close monitoring of electrolytes and renal function is crucial.
* **Hepatic Impairment:** Dose reduction may be necessary. Electrolyte and fluid balance are critical.
* **Concomitant medications:** Adjustments may be needed when used with other nephrotoxic agents, ototoxic drugs, or drugs that affect electrolytes.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
* Hepatic coma and severe electrolyte depletion.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, headache, weakness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), dehydration, hypotension, azotemia.
* **Less Common:** Hyperuricemia, hyperglycemia, tinnitus, hearing loss (especially with rapid IV administration or in renal impairment), rash, photosensitivity, pancreatitis, gastrointestinal upset.
## Key Drug Interactions
* **Aminoglycosides/Ototoxic drugs:** Increased risk of ototoxicity.
* **ACE inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to hypokalemia.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Lithium:** Reduced renal clearance, increased risk of lithium toxicity.
* **Potassium-sparing diuretics:** Can be used to counteract hypokalemia, but requires careful monitoring of potassium levels.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Blood pressure.
* Urine output.
* Hearing (especially with high doses or risk factors).
* Blood glucose and uric acid levels in susceptible patients.
## Clinical Pearls
* Furosemide is a potent diuretic; monitor for signs of dehydration and electrolyte depletion.
* Rapid IV administration can lead to ototoxicity; infuse slowly.
* Administering furosemide late in the day can lead to nocturia and sleep disturbances.
* For continuous IV infusion, an initial bolus is often given followed by a continuous infusion. The infusion rate needs to be adjusted based on patient response.
* Edematous patients may require higher oral doses than initially estimated due to altered absorption.
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*Please verify the most current prescribing information for specific indications, dosing, and safety information.*
