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# Furosemide
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver disease, and kidney disease, including nephrotic syndrome. It is also used to treat high blood pressure, alone or in combination with other antihypertensives.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:** 20-80 mg orally once daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. Doses may be given every other day or at larger intervals. The maximum daily oral dose is typically 600 mg, but doses up to 1 gram have been used in severe cases under close supervision.
* **Hypertension:** 40 mg orally twice daily. This dose is usually reserved for patients who are not adequately controlled with other diuretics.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose given once or twice daily. The maximum daily dose is 6 mg/kg. Doses should not exceed 40 mg per dose.
* Intravenous (IV): 1 mg/kg/dose given as a single dose. If inadequate response, subsequent doses may be increased by 1 mg/kg/dose. The maximum dose is 6 mg/kg/dose.
## Dose Adjustments
* **Renal Impairment:** Doses may need to be increased in patients with renal impairment due to decreased GFR and reduced tubular secretion. However, caution is advised as higher doses may lead to increased ototoxicity. Dose adjustments should be guided by patient response and monitoring.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended, but close monitoring for fluid and electrolyte imbalances is crucial.
## Contraindications
* Anuria.
* Hypersensitivity to furosemide or sulfonamides.
* Severe electrolyte depletion (e.g., hypokalemia, hyponatremia).
## Adverse Effects
* **Common:** Dizziness, lightheadedness, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia), dehydration, hypotension, azotemia.
* **Serious:** Ototoxicity (especially with rapid IV administration or high doses), hyperuricemia, hyperglycemia, rash, Stevens-Johnson syndrome, blood dyscrasias.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide.
* **Lithium:** Furosemide can decrease lithium clearance, increasing the risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity if hypokalemia or hypomagnesemia occurs.
## Monitoring
* **Electrolytes:** Serum electrolytes (sodium, potassium, chloride, magnesium) should be monitored regularly, especially during initiation and dose adjustments.
* **Renal Function:** Monitor BUN and serum creatinine.
* **Fluid Status:** Assess for signs of dehydration or fluid overload.
* **Blood Pressure:** Monitor blood pressure, especially in hypertensive patients.
* **Auditory Function:** Patients should be advised to report tinnitus or hearing loss.
## Clinical Pearls
* Oral furosemide is generally preferred for chronic conditions. IV administration is used for more rapid diuresis in acute situations.
* Rapid IV administration of furosemide (e.g., >4 mg/min) is associated with an increased risk of ototoxicity. Administer IV furosemide slowly, typically over 30-60 minutes.
* To minimize nocturia, administer the last dose of furosemide in the afternoon.
* For patients with severe edema and a poor response to oral furosemide, consider switching to IV administration or administering oral furosemide at higher doses or more frequently.
* Furosemide can cause or exacerbate metabolic alkalosis.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and consider individual patient factors before making any clinical decisions.*
