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# Furosemide (Oral)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to treat hypertension, usually in combination with other antihypertensives.
## Primary Indications
* Edema (associated with CHF, liver cirrhosis, renal disease, nephrotic syndrome)
* Hypertension
## Adult Dosing
* **Edema:** Typically starts at 20-80 mg once daily. Doses may be increased by 20-40 mg every 6-8 hours as needed. Doses greater than 80 mg/day should be given in divided doses. Doses as high as 600 mg/day have been used in severe cases.
* **Hypertension:** Typically 40 mg twice daily. May be used up to 80-120 mg/day in severe cases, usually in combination with other antihypertensives.
## Pediatric Dosing
* **Edema:** 1-4 mg/kg/dose orally once or twice daily. Maximum dose: 40 mg/day.
* **Hypertension:** 0.5-2 mg/kg/dose orally once or twice daily. Maximum dose: 40 mg/day.
* Note: Dosing in neonates and premature infants requires careful consideration due to immature renal function and potential for increased sensitivity; doses of 0.5-1 mg/kg/dose every 12-24 hours may be used.
## Dose Adjustments
* **Renal Impairment:** Dose may need to be increased in patients with renal impairment, but caution is advised. In severe renal impairment, efficacy may be reduced, and higher doses may be required.
* **Hepatic Impairment:** Dose reduction may be necessary due to altered pharmacokinetics.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and hypotension.**
* **Ototoxicity:** Especially with rapid IV administration or in patients with renal impairment, can be reversible or permanent.
* **Hyperuricemia and gout.**
* **Hyperglycemia.**
* **Photosensitivity.**
* **Aplastic anemia, agranulocytosis, thrombocytopenia, leukopenia** (rare but serious).
## Key Drug Interactions
* **Aminoglycosides, other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effect of furosemide and increase the risk of renal toxicity.
* **Lithium:** Increased risk of lithium toxicity due to decreased renal excretion.
* **Antihypertensives (e.g., ACE inhibitors, ARBs, beta-blockers):** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity in patients who develop hypokalemia or hypomagnesemia.
* **Ticlopidine:** Increased risk of thrombocytopenic purpura.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium), BUN, creatinine, and fluid status, especially with chronic use or dose changes.
* Blood pressure.
* Uric acid and glucose levels periodically.
* Hearing assessment may be considered, particularly in patients receiving high doses or those with risk factors for ototoxicity.
## Clinical Pearls
* Oral furosemide onset of action is typically within 1 hour, with peak effects in 1-2 hours, and duration of action of 4-6 hours.
* Monitor for signs and symptoms of dehydration (dizziness, dry mouth, decreased urine output) and electrolyte imbalances (muscle cramps, weakness, palpitations).
* To minimize nocturnal diuresis, administer the last dose in the late afternoon.
* Correct significant electrolyte disturbances and volume depletion before initiating therapy if possible.
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**Disclaimer:** This information is intended for healthcare professionals and does not replace comprehensive prescribing information. Always consult the current official prescribing information for the specific product being used.
