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# Furosemide
## Overview
Furosemide is a loop diuretic used to treat edema associated with heart failure, liver cirrhosis, and renal disease, including nephrotic syndrome. It is also used to treat hypertension, alone or in combination with other antihypertensives.
## Primary Indications
* Edema (congestive heart failure, liver cirrhosis, renal disease)
* Hypertension
## Adult Dosing
* **Edema:**
* Oral: Typically starts at 20-80 mg once or twice daily. Doses may be increased by 20-40 mg every 6-8 hours as needed.
* IV/IM: Typically starts at 20-40 mg once. Doses may be increased by 20 mg every 2 hours as needed. Higher doses (e.g., 80-100 mg) may be given as a bolus or continuous infusion. Dosing for IV administration should be about half the total daily oral dose.
* Maximum daily oral dose: 600 mg.
* Maximum daily IV dose: 200 mg (though higher doses may be used in specific, closely monitored situations).
* **Hypertension:**
* Oral: Typically 40 mg twice daily. Can be used alone or with other antihypertensives.
* Maximum daily oral dose: 600 mg.
* **Infants and Children (Edema):**
* Oral: 2 mg/kg/dose every 6 hours. May be increased to 6 mg/kg/dose every 6 hours if needed.
* IV/IM: 1 mg/kg/dose every 6 hours. May be increased to 2 mg/kg/dose every 6 hours if needed. Maximum single dose is 40 mg for both routes.
* *Note: Dosing in neonates can be highly variable and requires careful monitoring.*
## Dose Adjustments
* **Renal Impairment:** Patients with severe renal impairment may require higher doses due to reduced renal clearance and impaired drug delivery to the site of action. However, caution is still advised as they are also more susceptible to adverse effects.
* **Hepatic Impairment:** Reduced doses may be necessary due to altered pharmacokinetics and increased sensitivity to electrolyte and fluid disturbances.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalance (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, hyperuricemia.
* **Serious:** Severe electrolyte depletion, ototoxicity (especially with rapid IV administration or in renal impairment), severe hypotension, hyperglycemia, pancreatitis, Stevens-Johnson syndrome, aplastic anemia.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Antihypertensives:** Additive hypotensive effects.
* **Lithium:** Reduced lithium clearance, increasing the risk of lithium toxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Fluid balance (intake and output)
* Hearing (especially with high doses or rapid IV administration)
* Blood glucose (in diabetic patients)
* Uric acid
## Clinical Pearls
* Furosemide is a potent diuretic; administer with caution and monitor closely for dehydration and electrolyte imbalances.
* Oral administration may be delayed by about 1 hour compared to IV administration.
* IV administration of doses greater than 40 mg should be given slowly (over 30-60 minutes) to reduce the risk of ototoxicity.
* Rapid IV administration can cause hypotension and tinnitus.
* Patients with edema due to heart failure may require higher doses of furosemide than those with renal edema.
* Diurnal dosing (e.g., morning and early afternoon) can help avoid nocturia.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and relevant clinical guidelines for complete details and to verify dosage before administration.*
