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# Furosemide
## Overview
Furosemide is a potent loop diuretic used for the management of edema associated with heart failure, cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to treat hypertension, although it's not typically a first-line agent for this indication alone.
## Primary Indications
* Edema due to heart failure, cirrhosis, or renal disease (including nephrotic syndrome).
* Hypertension (adjunctive therapy).
## Adult Dosing
* **Edema:**
* **Oral:** The usual starting dose is 20-80 mg once daily. Doses can be increased by 20-40 mg every 6-8 hours as needed. The maintenance dose is individualized.
* **Intravenous (IV) or Intramuscular (IM):** The usual starting dose is 20-40 mg once daily. Doses can be increased by 20 mg every 2 hours as needed.
* **Maximum daily dose (oral or IV/IM):** Generally considered 600 mg, but higher doses may be used in specific situations under close medical supervision.
* **Hypertension:**
* **Oral:** 40 mg twice daily. (Note: This is generally not recommended as monotherapy for hypertension).
## Pediatric Dosing
Dosing varies widely and depends on the indication and the child's condition. **Specific dosing should be determined by a pediatrician or specialist.**
* **Edema:**
* **Oral:** Doses typically range from 1-4 mg/kg/day divided into 1-4 doses.
* **Intravenous (IV):** Doses typically range from 1 mg/kg/dose up to a maximum of 6 mg/kg/day divided into multiple doses.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be adjusted; however, furosemide is often still effective in renal failure, sometimes requiring higher doses. Monitor electrolytes and fluid status closely.
* **Hepatic Impairment:** May require dose reduction due to altered metabolism. Monitor for fluid and electrolyte imbalances.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides (caution advised, cross-reactivity is possible but rare).
* Severe electrolyte depletion (e.g., hypokalemia, hyponatremia).
## Adverse Effects
* **Common:** Dizziness, lightheadedness, dehydration, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), hypotension, thirst, increased urination.
* **Serious:** Ototoxicity (especially with rapid IV administration or high doses, or in conjunction with other ototoxic drugs), severe hypotension, hypovolemia, hyperglycemia, hyperuricemia (gout).
## Key Drug Interactions
* **Aminoglycosides and other ototoxic drugs:** Increased risk of ototoxicity.
* **Antihypertensives (including ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **Potassium-sparing diuretics:** May reduce the risk of hypokalemia but increase the risk of hyperkalemia.
* **Lithium:** Reduced renal clearance of lithium, increasing the risk of lithium toxicity.
## Monitoring
* Fluid status (weight, intake/output).
* Electrolytes (sodium, potassium, chloride, magnesium, calcium).
* Renal function (BUN, creatinine).
* Blood pressure.
* Blood glucose (in diabetic patients).
* Uric acid levels.
* Hearing (if concerns arise).
## Clinical Pearls
* Oral and IV doses are not always equivalent; IV doses may be more potent.
* Administer IV furosemide slowly (e.g., over 30-60 minutes) to minimize ototoxicity risk. Rapid IV push can lead to temporary hearing loss.
* Due to its short half-life, furosemide is often dosed once or twice daily for edema. For continuous diuresis, a continuous IV infusion may be considered.
* If hypokalemia occurs, consider potassium supplementation or a potassium-sparing diuretic.
* Monitor patients closely for signs of dehydration and electrolyte depletion, especially the elderly.
**Disclaimer:** This information is for educational purposes only and does not substitute for professional medical advice. Always verify current prescribing information with the official drug labeling and consult with a qualified healthcare provider before making any treatment decisions.
