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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver disease, and renal disease, as well as hypertension.
## Primary Indications
* Edema (congestive heart failure, cirrhosis, renal disease)
* Hypertension (adjunctive therapy)
* Acute pulmonary edema
## Adult Dosing
* **Edema:** Oral: 20 mg to 80 mg once daily, may increase by 20 mg to 40 mg every 6-8 hours. Initial dose usually 40 mg once daily. Maximum daily oral dose typically 600 mg, but higher doses may be used under specialist supervision. IV/IM: 20 mg to 40 mg once daily. For acute pulmonary edema, 40 mg IV may be given. Can titrate up to 80-100 mg IV for severe cases, with subsequent doses based on response.
* **Hypertension:** Oral: 40 mg twice daily. Generally not recommended as a first-line agent for hypertension alone.
## Pediatric Dosing
* **Edema:** Oral: 1 mg/kg to 2 mg/kg per dose every 6 to 12 hours. Maximum single dose 40 mg. IV/IM: 1 mg/kg per dose every 6 to 12 hours. Maximum single dose 20 mg. Doses may need to be individualized and adjusted based on response and renal function.
## Dose Adjustments
* **Renal Impairment:** Higher doses may be required due to decreased protein binding and impaired tubular secretion. Dosing should be individualized.
* **Hepatic Impairment:** Monitor for fluid and electrolyte imbalances.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia)
* Dehydration
* Hypotension
* Ototoxicity (especially with rapid IV administration or high doses)
* Hyperuricemia, hyperglycemia
* Dizziness, lightheadedness
## Key Drug Interactions
* **Aminoglycosides/Other Ototoxic Drugs:** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **ACE inhibitors/ARBs:** Increased risk of hypotension and renal dysfunction.
* **Potassium-sparing diuretics/Spironolactone/Eplerenone:** Monitor potassium closely.
* **Digoxin:** Increased risk of toxicity due to furosemide-induced hypokalemia.
* **Lithium:** Reduced renal clearance, increased risk of toxicity.
## Monitoring
* Electrolytes (serum sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Fluid balance (intake and output, weight)
* Blood pressure
* Hearing (especially with high doses or IV administration)
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize GI upset.
* IV administration should be slow (e.g., over 30-60 minutes) to reduce the risk of ototoxicity. Avoid rapid injection.
* Correction of electrolyte imbalances, especially hypokalemia, is crucial before initiating or continuing treatment, particularly with digoxin.
* Monitor weight daily for effective fluid management. A weight gain of 3 pounds or more in a day or 5 pounds or more in a week may indicate fluid retention.
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*Disclaimer: This information is intended for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider and refer to the official prescribing information for the most current and complete drug details.*
