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# Furosemide
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, cirrhosis, and renal disease, as well as hypertension.
## Primary Indications
* Edema (fluid overload) due to:
* Congestive heart failure (CHF)
* Liver cirrhosis
* Renal disease, including nephrotic syndrome
* Hypertension (usually in combination with other antihypertensives)
* Acute pulmonary edema
## Adult Dosing
* **Edema:**
* Oral: Initial dose 20-80 mg once daily. The dose may be increased by 20-40 mg every 6-8 hours as needed until desired response is achieved. Subsequent daily doses can be adjusted based on response.
* IV/IM: Initial dose 20-40 mg once daily. The dose may be increased by 20 mg every 2 hours as needed until desired response is achieved.
* Maximum oral dose: Typically 600 mg/day, but higher doses have been used in rare cases of severe edema under close monitoring.
* Maximum IV/IM dose: Typically 200 mg per dose, but higher doses may be required in severe cases.
* **Hypertension:**
* Oral: 40 mg twice daily. May be adjusted to 20-120 mg/day in divided doses. Typically used in combination with other antihypertensives.
* **Acute Pulmonary Edema:**
* IV: 40 mg administered as a rapid injection. If response is inadequate after 2 hours, a second dose of 80 mg can be administered. Further doses may be given every 2-4 hours as needed.
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose once daily. The dose may be increased by 1 mg/kg/dose every 6-8 hours as needed. The maximum daily dose should not exceed 6 mg/kg.
* IV/IM: 1 mg/kg/dose once daily. If inadequate response, the dose may be increased by 1 mg/kg/dose every 2 hours. The maximum daily dose should not exceed 6 mg/kg.
## Dose Adjustments
* **Renal Impairment:** Dose adjustments may be needed; however, furosemide is often used to treat edema in renal disease. Monitor for efficacy and electrolyte imbalances.
* **Hepatic Impairment:** Dose adjustments may be needed, particularly in patients with cirrhosis, due to altered drug metabolism and increased risk of electrolyte disturbances.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or sulfonamides (cross-sensitivity may occur)
## Adverse Effects
* **Common:** Dizziness, lightheadedness, headache, electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia), dehydration, hypotension, azotemia.
* **Less Common:** Hyperuricemia, hyperglycemia, ototoxicity (especially with rapid IV administration or high doses), rash, pruritus, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides & other ototoxic drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce natriuretic and antihypertensive effects, and increase risk of renal impairment.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Increased risk of lithium toxicity due to reduced renal clearance.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or rapid IV infusion)
* Blood glucose and uric acid levels (in susceptible patients)
## Clinical Pearls
* Administer oral furosemide with or without food. If given with food, it may be absorbed more slowly.
* IV administration should be given slowly (over at least 30 seconds for doses up to 40 mg, and over 1-2 minutes for higher doses) to minimize the risk of ototoxicity.
* Furosemide can cause significant fluid and electrolyte losses. Regular monitoring is essential, especially in patients with comorbidities.
* Oral administration can be given once daily in the morning to minimize nocturia. For edema, if a single dose is insufficient, a second dose can be given in the early afternoon.
* For patients with severe edema unresponsive to oral therapy, continuous IV infusion may be more effective than intermittent bolus doses.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult current prescribing information and your institution's protocols for definitive guidance.*
