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# Furosemide
## Overview
Furosemide is a loop diuretic used to treat fluid overload (edema) associated with heart failure, liver disease, and kidney disease, including nephrotic syndrome. It is also used to treat high blood pressure.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:**
* **Oral:** Initial dose is typically 20 mg to 80 mg once daily. Doses may be increased by 20 mg to 40 mg every 6 to 8 hours as needed. The usual maintenance dose is 40 mg to 120 mg daily, but may be as high as 600 mg daily in severe cases, divided into doses.
* **Intravenous (IV) or Intramuscular (IM):** Initial dose is typically 20 mg to 40 mg once daily. If no adequate diuresis is achieved, doses may be increased by 20 mg every 2 hours. The usual maintenance dose is 40 mg to 80 mg once daily. For patients with severe edema, continuous IV infusion may be initiated at 4 mg/minute after an initial IV bolus of 20 mg to 40 mg.
* **Hypertension:**
* **Oral:** Initial dose is typically 20 mg to 40 mg once daily. Doses may be adjusted based on response. Doses higher than 40 mg are not usually effective in lowering blood pressure.
## Pediatric Dosing
* **Edema:**
* **Oral:** 1 mg/kg to 2 mg/kg per dose once daily. The maximum dose is 6 mg/kg per day. Doses can be given once or twice daily.
* **Intravenous (IV) or Intramuscular (IM):** 1 mg/kg per dose once daily. The maximum dose is 6 mg/kg per day. For continuous infusion, a rate of 0.1 mg/kg/hour may be used.
## Dose Adjustments
* **Renal Impairment:** Dose reduction may be necessary, particularly in patients with severe renal impairment. Continuous infusion may be preferred over bolus dosing in some cases.
* **Hepatic Impairment:** Caution and dose reduction may be required.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
* Hepatic coma or severe electrolyte depletion.
## Adverse Effects
* **Electrolyte Imbalance:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and Hypotension:** Especially with rapid diuresis.
* **Ototoxicity:** Usually reversible, but can be permanent with high doses or rapid IV administration.
* **Hyperuricemia and Gout.**
* **Hyperglycemia.**
* **Dizziness, lightheadedness.**
* **Rash, photosensitivity.**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **Lithium:** Increased risk of lithium toxicity due to reduced renal clearance.
* **Antihypertensives:** Additive hypotensive effect.
* **Digoxin:** Increased risk of toxicity due to furosemide-induced hypokalemia.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Theophylline:** May decrease clearance of theophylline.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Blood pressure.
* Fluid intake and output.
* Hearing (especially with high doses).
* Blood glucose (in diabetic patients).
## Clinical Pearls
* Administer oral furosemide with or without food. If given with food, it may decrease absorption slightly.
* To minimize nocturia, administer the last dose of the day at least 4 hours before bedtime.
* Rapid IV administration can increase the risk of ototoxicity and hypotension. Inject IV furosemide slowly.
* Patients with severe edema may require higher doses or continuous infusion. The maximum daily oral dose is generally considered 600 mg, though higher doses have been used under specialist supervision. The maximum IV dose is typically 100 mg per dose, but higher doses may be given by infusion.
* Furosemide can cause metabolic alkalosis due to volume and chloride depletion.
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*This information is intended for healthcare professionals. Always consult the official prescribing information and relevant clinical guidelines for the most up-to-date and comprehensive details.*
