Overview
Furosemide is a potent loop diuretic used to treat edema associated with heart failure, liver cirrhosis, renal disease, and hypertension. It works by inhibiting sodium and chloride reabsorption in the ascending loop of Henle, leading to increased urine output and reduced fluid retention.
Mechanism of Action
Furosemide inhibits the Na+/K+/2Cl- cotransporter in the thick ascending limb of the loop of Henle in the kidney, reducing sodium and chloride reabsorption. This increases the excretion of sodium, chloride, potassium, calcium, magnesium, and water, leading to diuresis and reduced extracellular fluid volume.
Indications
- Edema associated with congestive heart failure, cirrhosis of the liver, and renal disease
- Hypertension
- Acute pulmonary edema
Dosage
Dosage varies based on condition: For edema: 20-80 mg orally once daily, may increase by 20-40 mg every 6-8 hours; For hypertension: 40 mg orally twice daily, adjust based on response; IV/IM: 20-40 mg, may repeat in 1-2 hours. Adjust in renal impairment.
Contraindications
- Anuria
- Hypersensitivity to furosemide or sulfonamides
- Hepatic coma
- Severe electrolyte depletion
Side Effects
- Hypokalemia
- Hypotension
- Dehydration
- Ototoxicity (tinnitus, hearing loss)
- Hyperglycemia
- Hyperuricemia
- Nausea, vomiting, diarrhea
- Dizziness, headache
- Photosensitivity
- Pancreatitis
Interactions
- Aminoglycosides: Increased risk of ototoxicity
- Digoxin: Hypokalemia may increase digoxin toxicity
- Lithium: Reduced renal clearance of lithium, risk of toxicity
- NSAIDs: Reduced diuretic effect
- Probenecid: Reduced diuretic effect
- Antihypertensives: Additive hypotensive effect
- Corticosteroids: Increased risk of hypokalemia