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# Furosemide
## Overview
Furosemide is a loop diuretic used to reduce fluid overload.
## Primary Indications
* Edema associated with congestive heart failure (CHF), cirrhosis, and renal disease.
* Hypertension (less commonly used as monotherapy).
## Adult Dosing
* **Edema:**
* Oral: Initial dose is typically 20-80 mg once or twice daily. The dose may be increased by 20-40 mg every 6-8 hours as needed.
* Intravenous (IV): Initial dose is typically 20-40 mg once. If no adequate response, subsequent doses may be increased by 20 mg every 2 hours.
* Continuous IV infusion: 4 mg/hour after an initial IV bolus of 40-80 mg.
* **Hypertension:**
* Oral: 40 mg twice daily.
* **Maximum Daily Oral Dose:** Generally 600 mg, but higher doses may be used in rare cases under close supervision.
* **Maximum IV Dose:** No strict maximum, but doses exceeding 200 mg in 24 hours are uncommon and require careful monitoring.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose every 6-12 hours. Maximum dose 6 mg/kg/day.
* IV: 1 mg/kg/dose every 6-12 hours. Maximum dose 6 mg/kg/day.
* Continuous IV infusion: 0.1-0.2 mg/kg/hour.
## Dose Adjustments
* **Renal Impairment:** Lower initial doses and slower titration may be necessary. In severe renal impairment, higher doses may be required due to resistance.
* **Hepatic Impairment:** Caution is advised; doses may need to be reduced.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or its sulfonamide derivatives.
* Electrolyte depletion (e.g., hyponatremia, hypokalemia, hypochloremia).
## Adverse Effects
* **Common:** Dizziness, lightheadedness, orthostatic hypotension, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, azotemia.
* **Serious:** Severe electrolyte disturbances, ototoxicity (especially with rapid IV administration or in renal impairment), hyperglycemia, hyperuricemia, Stevens-Johnson syndrome, aplastic anemia.
## Key Drug Interactions
* **Aminoglycosides, Cisplatin:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effects.
* **Lithium:** Increased risk of lithium toxicity.
* **Potassium-Sparing Diuretics (e.g., spironolactone):** Can help counteract hypokalemia but may lead to hyperkalemia.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium) at baseline and periodically.
* Renal function (BUN, creatinine).
* Blood pressure, especially with antihypertensive use or rapid diuresis.
* Fluid intake and output.
* Hearing (if ototoxicity is suspected).
* Blood glucose in diabetic patients.
* Uric acid levels.
## Clinical Pearls
* Administer IV furosemide slowly (e.g., over 30-60 minutes) to minimize the risk of ototoxicity. Avoid rapid IV push in adults if possible.
* Monitor for signs and symptoms of electrolyte imbalance (e.g., muscle cramps, weakness, confusion, arrhythmias).
* Educate patients about the risk of orthostatic hypotension and advise them to rise slowly.
* Consider potassium supplementation or adding a potassium-sparing diuretic if hypokalemia is significant or persistent.
* The efficacy of furosemide can be reduced in patients with the nephrotic syndrome.
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*Disclaimer: This information is intended for clinical use and does not replace professional judgment. Always consult the most current prescribing information and institutional protocols before initiating or adjusting drug therapy.*
