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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to treat fluid overload and edema.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Hepatic cirrhosis
* Renal disease (including nephrotic syndrome)
* Pulmonary edema (acute)
* Hypertension (adjunct therapy, less common)
## Adult Dosing
* **Edema:**
* **Oral:** 20-80 mg once daily. Doses can be increased by 20-40 mg every 6-8 hours until desired response is achieved. Maximum daily dose is generally 600 mg, but higher doses may be used in refractory edema under close supervision. Doses greater than 80 mg are often divided.
* **Intravenous (IV) / Intramuscular (IM):** 20-40 mg once daily. If insufficient response, may increase dose or administer more frequently. IV doses should be administered slowly (e.g., over 30-60 minutes) to avoid ototoxicity. Maximum daily IV dose is generally 600 mg, but higher doses may be used in refractory edema under close supervision. Convert to oral therapy as soon as clinically feasible.
* **Hypertension (adjunct):** 40 mg twice daily. Typically used in patients with concurrent edema.
## Pediatric Dosing
* **Edema:**
* **Oral:** 1-2 mg/kg/dose every 6-12 hours. Maximum dose 6 mg/kg/day.
* **Intravenous (IV) / Intramuscular (IM):** 1 mg/kg/dose every 6-12 hours. Maximum dose 6 mg/kg/day. Neonates may have altered pharmacokinetics; doses typically range from 0.5-2 mg/kg/dose every 12-24 hours.
## Dose Adjustments
* **Renal Impairment:** Patients with renal impairment may require lower doses or less frequent administration due to reduced clearance. However, significant edema in renal failure often requires aggressive diuresis, sometimes necessitating higher doses. Monitor response carefully.
* **Hepatic Impairment:** Dose adjustments may be necessary, though often similar doses are used. Monitor electrolytes and fluid status closely.
## 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 high doses).
* **Hyperuricemia** (can precipitate gout).
* **Hyperglycemia.**
* **Increased BUN and creatinine.**
* Dizziness, headache, nausea, vomiting.
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Other ototoxic drugs (e.g., cisplatin):** Increased risk of ototoxicity.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Lithium:** Reduced renal clearance of lithium, increasing risk of lithium toxicity.
* **Antihypertensives:** Additive hypotensive effect.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Fluid status (weight, intake/output)
* Renal function (BUN, creatinine)
* Blood pressure
* Hearing (especially with high doses or rapid IV administration)
## Clinical Pearls
* Administer oral furosemide in the morning to minimize nocturnal diuresis.
* For patients with refractory edema, consider continuous IV infusion or higher doses administered cautiously.
* Electrolyte supplementation, particularly potassium, is often necessary.
* Paradoxical worsening of edema or hyponatremia can occur in patients with the syndrome of inappropriate antidiuretic hormone (SIADH) if furosemide is used without sodium repletion.
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*This information is intended for healthcare professionals. Always consult the official prescribing information and consider individual patient factors before making clinical decisions. Dosing and recommendations may vary based on local protocols and guidelines.*
