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# Furosemide (Oral)
## Overview
Furosemide is a potent loop diuretic used for the management of edema associated with heart failure, liver cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to lower blood pressure, usually in combination with other antihypertensives.
## Primary Indications
* Edema associated with congestive heart failure, liver cirrhosis, and renal disease (including nephrotic syndrome).
* Hypertension (adjunctive therapy).
## Adult Dosing
* **Edema:**
* **Initial:** 20-80 mg orally once daily. Doses may be given as a single dose or divided doses.
* **Maintenance:** 20-40 mg orally once or twice daily. Some patients may require higher doses up to 80 mg twice daily.
* **Maximum:** 600 mg daily in divided doses for patients with severe edema, though doses exceeding 80 mg may not provide additional benefit and can increase the risk of adverse effects.
* **Hypertension:**
* **Initial:** 40 mg orally twice daily.
* **Maintenance:** Adjust dose based on response. May be used in combination with other antihypertensives.
* **Maximum:** Typically 120 mg daily.
## Pediatric Dosing
* **Edema:**
* **Infants < 2 months:** 1 mg/kg/dose orally once daily. Increase by 1 mg/kg/dose every 2 days as needed. Maximum 6 mg/kg/day.
* **Infants > 2 months and Children:** 1-2 mg/kg/dose orally once daily. Increase by 1-2 mg/kg/dose every 2 days as needed. Maximum 6 mg/kg/day or 40 mg/day, whichever is less.
* Some sources recommend starting with 1 mg/kg/dose orally every 12-24 hours.
## Dose Adjustments
* **Hepatic Impairment:** Use with caution and consider lower doses due to increased bioavailability and potential for electrolyte imbalances.
* **Renal Impairment:** Dose may need to be increased in renal impairment to achieve a diuretic effect, but monitor closely for toxicity.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Electrolyte disturbances:** Hyponatremia, hypokalemia, hypochloremia, metabolic alkalosis, hypomagnesemia, hypocalcemia.
* **Dehydration:** Dizziness, orthostatic hypotension.
* Ototoxicity (especially with rapid IV administration or high doses).
* Hyperglycemia.
* Increased BUN.
* Rash, pruritus.
* Gout exacerbation.
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **ACE inhibitors, ARBs, potassium-sparing diuretics:** Increased risk of hyperkalemia.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced renal clearance of lithium, increased risk of lithium toxicity.
## Monitoring
* **Electrolytes:** Sodium, potassium, chloride, magnesium, calcium.
* **Renal function:** BUN, creatinine.
* **Fluid balance:** Daily weights, intake/output.
* **Blood pressure:** Especially when used for hypertension.
* **Blood glucose:** In patients with diabetes.
* **Auditory function:** Especially with high doses or in those with risk factors for hearing loss.
## Clinical Pearls
* Oral furosemide absorption can be variable. Food may delay but does not significantly affect absorption.
* Dosing should be individualized based on patient response and degree of fluid overload.
* To minimize nocturia, administer the last dose at least 4-6 hours before bedtime.
* Close monitoring for electrolyte imbalances and dehydration is crucial, particularly in elderly patients or those with significant comorbidities.
* In patients with severe edema, consider alternative dosing strategies or intravenous administration if oral efficacy is poor.
**Please consult the most current prescribing information for complete details and to verify this information before use.**
