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# Furosemide (Lasix)
## Overview
Furosemide is a loop diuretic used to treat fluid overload (edema) due to heart failure, liver disease, or kidney disease. It is also used to treat high blood pressure, sometimes in combination with other medications.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with liver cirrhosis
* Edema associated with renal disease, including nephrotic syndrome
* Hypertension (alone or in combination)
## Adult Dosing
* **Edema:**
* Initial: 20-80 mg orally once daily. Doses may be given every 12 hours or as a single dose.
* Maximum: 600 mg orally per day, though higher doses may be used under close supervision in severe cases.
* The dose should be adjusted based on response and fluid status. For patients requiring higher doses or those with significant edema, intermittent intravenous or intramuscular administration may be considered.
* **Hypertension:**
* Initial: 40 mg orally once daily.
* Doses may be adjusted upwards based on response, up to a maximum of 120 mg orally per day, typically divided into two doses.
* Often used in combination therapy.
## Pediatric Dosing
* **Edema/Hypertension:**
* Initial: 1-2 mg/kg orally once daily.
* Maximum: 6 mg/kg orally per day.
* Doses can be given every 12 hours if needed. Dosing should be individualized and carefully monitored.
## Dose Adjustments
* **Renal Impairment:** In patients with significant renal impairment, higher doses may be required due to decreased drug effect or altered pharmacokinetics. Closely monitor electrolytes and fluid status.
* **Hepatic Impairment:** Caution is advised due to potential for increased furosemide bioavailability and increased risk of electrolyte imbalances.
## Contraindications
* Anuria
* Known hypersensitivity to furosemide or its sulfonamide constituents.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration:** Dizziness, orthostatic hypotension, weakness.
* **Ototoxicity:** Hearing loss (usually reversible, more common with rapid IV administration or high doses).
* **Metabolic:** Hyperuricemia, hyperglycemia.
* **Gastrointestinal:** Nausea, diarrhea, abdominal pain.
* **Dermatologic:** Rash, photosensitivity.
## Key Drug Interactions
* **Aminoglycosides, Cisplatin:** Increased risk of ototoxicity.
* **Other Diuretics (Thiazides, Potassium-Sparing):** Additive diuretic effect, increased risk of electrolyte disturbances.
* **NSAIDs:** May reduce the natriuretic and diuretic effect of furosemide.
* **Lithium:** Furosemide can decrease renal clearance of lithium, increasing lithium toxicity risk.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Warfarin:** Furosemide can displace warfarin from protein binding sites, potentially increasing warfarin's anticoagulant effect.
## Monitoring
* Serum electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or IV administration)
* Blood glucose and uric acid levels
## Clinical Pearls
* Furosemide is a potent diuretic; monitor for signs of dehydration and electrolyte depletion.
* Oral administration of furosemide is generally effective unless absorption is impaired or rapid diuresis is required.
* In patients with edema, the goal is to achieve a weight loss of approximately 1-2 kg per day.
* Concurrent potassium supplementation or use of potassium-sparing diuretics may be necessary to prevent hypokalemia, especially with long-term use or higher doses.
* Ototoxicity is a risk, particularly with rapid intravenous infusion or very high doses.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.*
