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# Furosemide (Oral)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with congestive heart failure, liver cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to manage hypertension, although it is not typically a first-line agent for this indication.
## Primary Indications
* Edema (congestive heart failure, liver cirrhosis, renal disease, nephrotic syndrome)
* Hypertension
## Adult Dosing
**Edema:**
* Initial dose: 20-80 mg orally once daily.
* If no response within 6-8 hours, the dose may be increased by 20-40 mg every 6-8 hours.
* Subsequent doses should be adjusted based on response.
* Maintenance dose: Usually the smallest dose that will maintain the desired clinical effect. Doses can range from 20 mg every other day to 200 mg daily, divided into 1-4 doses.
* Maximum daily dose: Not well established, but doses exceeding 600 mg daily have been used in rare cases of severe refractory edema.
**Hypertension:**
* Initial dose: 40 mg orally twice daily.
* This dose is generally not recommended for primary treatment of hypertension.
## Pediatric Dosing
**Edema:**
* 20 mg orally once daily initially.
* If inadequate response, increase dose by 1-2 mg/kg/day every 6-8 hours.
* Maximum daily dose: 6 mg/kg.
* For chronic therapy, doses may be given once or twice daily.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Higher doses may be needed due to impaired absorption and excretion. Monitor for electrolyte imbalances.
* **Hepatic Impairment:** Use with caution. May precipitate hepatic coma in patients with severe liver disease. Monitor closely.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur).
## Adverse Effects
* **Common:** Dizziness, lightheadedness, dehydration, hypotension, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), hyperuricemia, hyperglycemia.
* **Less Common:** Ototoxicity (especially with rapid IV administration or high doses), rash, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **Antihypertensives (including ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Corticosteroids/ACTH:** Increased risk of electrolyte depletion, particularly hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May decrease the diuretic and antihypertensive effects of furosemide.
* **Lithium:** Reduced renal clearance of lithium, increasing risk of lithium toxicity.
* **Potassium-Sparing Diuretics (e.g., spironolactone, amiloride):** Counteract potassium loss; use cautiously to avoid hyperkalemia.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood glucose
* Uric acid
* Fluid balance (intake and output, weight)
* Blood pressure
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize gastrointestinal upset.
* Rapid diuresis can lead to hypotension and electrolyte disturbances; titrate dose to achieve gradual fluid removal.
* Regular monitoring of electrolytes is crucial, especially in elderly patients, those with significant edema, or those on concurrent medications that affect electrolytes.
* Hypokalemia is a common and significant adverse effect; dietary potassium supplementation or potassium-sparing diuretics may be necessary.
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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 relevant clinical guidelines before making therapeutic decisions.*
