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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic used to manage edema associated with heart failure, liver cirrhosis, and renal disease, including nephrotic syndrome. It is also used to treat hypertension, although it is not typically a first-line agent for this indication alone.
## Primary Indications
* Edema due to heart failure
* Edema due to liver cirrhosis
* Edema due to renal disease
* Hypertension (adjunctive therapy)
## Adult Dosing
* **Edema:**
* Oral: Initial dose is typically 20-80 mg once or twice daily. Doses can be increased by 20-40 mg every 6-8 hours as needed. The usual maintenance dose is 40-120 mg daily, but some patients may require up to 600 mg daily.
* Intravenous (IV)/Intramuscular (IM): Initial dose is typically 20-40 mg once. If insufficient response, doses can be increased by 20 mg every 2 hours or given as a continuous infusion. The maximum daily dose via IV/IM is generally 600 mg, but may be higher in specific cases under close monitoring.
* **Hypertension:**
* Oral: Initial dose is typically 40 mg twice daily. Doses may be adjusted based on response.
## Pediatric Dosing
* **Edema:**
* Oral: 1-4 mg/kg/day divided into 1-4 doses. Maximum daily dose is 40 mg. Higher doses may be used in severe cases under specialist supervision.
* IV/IM: 1 mg/kg/dose. Maximum dose is 20 mg/dose. Higher doses may be used in severe cases under specialist supervision.
## Dose Adjustments
* **Renal Impairment:** Furosemide is renally excreted; dose adjustments may be necessary. In severe renal impairment, higher doses may be required, but caution is advised.
* **Hepatic Impairment:** Patients with cirrhosis may be more sensitive to the effects of furosemide and may develop hepatic encephalopathy. Lower initial doses are recommended.
## Contraindications
* Anuria
* Hypersensitivity to furosemide or sulfonamides
## Adverse Effects
* **Electrolyte disturbances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and hypotension:** Especially with rapid diuresis.
* **Ototoxicity:** Usually associated with rapid IV administration or high doses.
* **Hyperglycemia, hyperuricemia.**
* **Dermatologic reactions:** Rash, photosensitivity.
* **Renal toxicity.**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Other diuretics:** Additive effects, increasing risk of dehydration and electrolyte imbalances.
* **NSAIDs:** May reduce diuretic and antihypertensive effect.
* **Lithium:** Reduced renal clearance, increasing lithium toxicity risk.
* **Antihypertensives:** Additive hypotensive effects.
* **Corticosteroids:** Increased risk of hypokalemia.
## Monitoring
* **Electrolytes:** Serum sodium, potassium, chloride, magnesium, calcium.
* **Renal function:** Serum creatinine, BUN.
* **Fluid balance:** Intake and output, daily weights.
* **Blood pressure.**
* **Auditory function:** If high doses or rapid IV administration.
## Clinical Pearls
* Administer oral furosemide preferably on an empty stomach for better absorption, but may be taken with food or milk if gastric upset occurs.
* For edema, doses should be individualized based on patient response and tolerance.
* IV administration is generally more potent and has a faster onset of action than oral.
* Continuous IV infusion may be more effective than intermittent dosing in patients with severe renal insufficiency or severe edema refractory to intermittent therapy.
* Monitor for signs and symptoms of electrolyte imbalances and dehydration.
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*Disclaimer: This information is intended for healthcare professionals and should not replace clinical judgment or consultation of the most current prescribing information or local protocols. Always verify drug information with official sources before administration.*
