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# Furosemide (Lasix)
## Overview
Furosemide is a potent loop diuretic that inhibits the reabsorption of sodium and chloride in the ascending limb of the loop of Henle, leading to increased excretion of water, sodium, chloride, potassium, calcium, and magnesium.
## Primary Indications
* Edema associated with congestive heart failure (CHF)
* Edema associated with hepatic cirrhosis
* Edema associated with renal disease, including nephrotic syndrome
* Hypertension (adjunctive therapy)
* Acute pulmonary edema
## Adult Dosing
* **Edema:**
* Oral: 20-80 mg once daily. May increase by 20-40 mg every 6-8 hours as needed. Usual maintenance dose is 40-80 mg daily. Doses up to 600 mg/day have been used in severe cases, but higher doses are less effective and increase risk of adverse effects.
* Intravenous/Intramuscular: 20-40 mg once daily. May increase by 20 mg every 2 hours as needed. Usual maintenance dose is 40-80 mg daily. In resistant edema, doses up to 80-100 mg IV may be given once. Continuous infusion may be used for severe edema (e.g., 4 mg/minute after an initial bolus of 40-80 mg).
* **Hypertension:**
* Oral: 40 mg twice daily.
* **Acute Pulmonary Edema:**
* Intravenous: 20-40 mg. If response is inadequate, subsequent doses of 40 mg IV may be administered after 2 hours.
*Dosing depends on individual response and severity of condition. Specific titration protocols may be followed based on local guidelines.*
## Pediatric Dosing
* **Edema:**
* Oral: 1-2 mg/kg/dose every 6-12 hours. Doses may be increased by 1 mg/kg/dose every 6-8 hours as needed. Maximum dose: 6 mg/kg/day.
* Intravenous/Intramuscular: 1 mg/kg/dose every 6-12 hours. Maximum dose: 6 mg/kg/day.
* Premature infants: 0.5-1 mg/kg/dose every 12-24 hours.
## Dose Adjustments
* **Renal Impairment:** Furosemide is eliminated renally. In patients with renal insufficiency, higher doses may be required to achieve diuresis. However, monitor closely for increased accumulation and potential ototoxicity with very high doses. In patients with anuria, furosemide may be ineffective.
* **Hepatic Impairment:** Caution is advised. Electrolyte imbalances may precipitate hepatic encephalopathy.
## Contraindications
* Anuria
* History of 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, gout
* Hyperglycemia
* Dizziness, lightheadedness
* Photosensitivity
* Rash
* Aplastic anemia, agranulocytosis, thrombocytopenia (rare)
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects.
* **Lithium:** Furosemide can decrease lithium clearance, increasing the risk of lithium toxicity.
* **Corticosteroids:** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **Antihypertensives:** Additive hypotensive effects.
* **Sucralfate:** May decrease the absorption of furosemide. Administer furosemide at least 1 hour before or 4-6 hours after sucralfate.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Blood glucose (in diabetic patients)
* Uric acid
* Hearing (especially with high doses or rapid IV administration)
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize GI upset.
* Rapid IV administration can increase the risk of ototoxicity. Infuse slowly over 30-60 minutes or as a continuous infusion.
* Monitor for signs and symptoms of electrolyte depletion, such as muscle cramps, weakness, confusion, and cardiac arrhythmias.
* Potassium supplementation may be necessary for patients on chronic furosemide therapy.
* Be aware of potential for dose-related hearing loss, which may be temporary or permanent.
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*This information is intended for healthcare professionals and does not replace the need to consult the official prescribing information or other relevant clinical resources for the most current and complete details.*
