Furosemide is a high-ceiling loop diuretic indicated for the management of edema associated with congestive heart failure, cirrhosis of the liver, and renal disease, including the nephrotic syndrome. It acts primarily on the thick ascending limb of the loop of Henle to inhibit the reabsorption of sodium and chloride, resulting in profound diuresis. This agent is particularly valuable in clinical scenarios requiring rapid and significant fluid removal, offering a critical therapeutic option for patients with fluid overload resistant to other diuretics. Its predictable pharmacokinetics and well-established efficacy profile make it a cornerstone in both acute and chronic care settings.

Features

• Active ingredient: Furosemide
• Drug class: Loop diuretic
• Available forms: Oral tablets, oral solution, intravenous injection, intramuscular injection
• Mechanism of action: Inhibits the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle
• Onset of action: Oral: 30-60 minutes; IV: within 5 minutes
• Peak effect: Oral: 1-2 hours; IV: 30 minutes
• Duration of action: 6-8 hours
• Bioavailability: 60-70% (oral)
• Protein binding: >98%
• Metabolism: Hepatic (minimal)
• Excretion: Primarily renal (unchanged), fecal (minor)
• Half-life: Approximately 2 hours (prolonged in renal impairment)

Benefits

• Rapid and significant reduction of edema in congestive heart failure, facilitating improved cardiac function and symptom relief
• Effective management of pulmonary edema through prompt diuresis, enhancing respiratory function
• Useful in controlling hypertension, particularly in patients with renal impairment or resistance to thiazide diuretics
• Provides flexible dosing options (oral and parenteral) suitable for both outpatient and acute care settings
• Helps correct fluid and electrolyte imbalances in hepatic cirrhosis with ascites
• Supports management of hypercalcemia through enhanced calcium excretion

Common use

Furosemide is primarily prescribed for the treatment of edema associated with congestive heart failure, liver cirrhosis, and renal impairment, including nephrotic syndrome. It is also used in the management of hypertension, either alone or in combination with other antihypertensive agents. In hospital settings, intravenous furosemide is frequently administered for acute pulmonary edema and for forced diuresis in the treatment of certain drug intoxications. Off-label uses include treatment of hypercalcemia and as adjunctive therapy in patients with acute renal failure to convert oliguric to non-oliguric failure.

Dosage and direction

Oral administration:

• Edema: Initial dose 20-80 mg as a single dose, may increase by 20-40 mg every 6-8 hours until desired diuretic response
• Maintenance: May be given once or twice daily (e.g., 20-80 mg/day)
• Hypertension: Initial dose 40 mg twice daily, adjusted according to response
• Maximum dose: 600 mg/day in divided doses for severe edema

Parenteral administration:

• IV/IM: 20-40 mg, may be repeated in 2 hours and increased by 20 mg until desired response
• Continuous IV infusion: Loading dose 20-40 mg followed by 0.1-0.4 mg/min
• Renal impairment: Higher doses may be required; monitor closely

Take oral doses in the morning to avoid nocturnal diuresis. Administer with food to minimize gastrointestinal upset. Monitor blood pressure, renal function, and electrolytes regularly.

Precautions

• Monitor serum electrolytes (particularly potassium, sodium, and magnesium), blood urea nitrogen, creatinine, and uric acid regularly
• Use caution in patients with sulfonamide allergy (cross-sensitivity may occur)
• Risk of ototoxicity, especially with rapid IV administration, high doses, or concurrent use of other ototoxic drugs
• May precipitate or worsen gout due to increased uric acid levels
• Use with caution in patients with hepatic impairment due to risk of hepatic encephalopathy
• Photosensitivity reactions may occur; advise sun protection
• Elderly patients may be more susceptible to dehydration and electrolyte disturbances
• May increase blood glucose levels; monitor diabetics closely

Contraindications

• Anuria unresponsive to furosemide trial dose
• Severe electrolyte depletion (hypokalemia, hyponatremia)
• Hepatic coma or severe hepatic impairment with encephalopathy
• Hypersensitivity to furosemide or sulfonamide-derived drugs
• Concomitant use with aminoglycosides in renal impaired patients (increased ototoxicity risk)
• Patients with documented sulfa allergy

Possible side effect

Common (≥1%):

• Dehydration
• Hypokalemia
• Hyponatremia
• Hypochloremia
• Hypomagnesemia
• Hyperglycemia
• Hyperuricemia
• Orthostatic hypotension
• Dizziness
• Headache
• Nausea

Less common (<1%):

• Ototoxicity (tinnitus, hearing loss)
• Pancreatitis
• Photosensitivity
• Blood dyscrasias (thrombocytopenia, agranulocytosis)
• Stevens-Johnson syndrome
• Interstitial nephritis
• Cholecystitis
• Blurred vision

Drug interaction

• Digoxin: Hypokalemia may increase risk of digitalis toxicity
• Lithium: Reduced renal clearance may cause lithium toxicity
• NSAIDs: May reduce diuretic and antihypertensive effects
• Aminoglycosides: Increased risk of ototoxicity and nephrotoxicity
• Probenecid: May decrease diuretic effect
• Antihypertensives: Enhanced hypotensive effect
• Corticosteroids: Enhanced potassium wasting
• Sucralfate: May reduce absorption of furosemide
• Salicylates: Increased risk of salicylate toxicity at lower doses
• Cisplatin: Increased risk of ototoxicity and nephrotoxicity

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose to make up for a missed one. For twice-daily regimens, if remembered within 4 hours of the scheduled time, take the missed dose; otherwise, skip and resume normal schedule. For once-daily dosing, take when remembered unless within 8 hours of next dose.

Overdose

Symptoms include profound water loss, electrolyte depletion (particularly hypokalemia), dehydration, reduction in blood volume, circulatory collapse, and possibly vascular thrombosis and embolism. Treatment involves cessation of therapy, electrolyte replacement, and supportive care. Hemodialysis does not significantly enhance elimination. Monitor fluid and electrolyte status closely and provide appropriate volume replacement.

Storage

Store at controlled room temperature (20-25°C or 68-77°F). Protect from light and moisture. Keep in original container with lid tightly closed. Do not freeze oral solution. Discard any unused portion of oral solution after 90 days. Parenteral solutions should be inspected for particulate matter and discoloration before administration.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Furosemide is a prescription medication that should be used only under the supervision of a qualified healthcare professional. Dosage and administration must be individualized based on the patient’s clinical condition, renal function, and response to therapy. Patients should not initiate, adjust, or discontinue therapy without consulting their healthcare provider.

Reviews

“Furosemide remains the gold standard for rapid diuresis in our cardiac care unit. Its predictable response and flexible dosing make it indispensable for managing acute decompensated heart failure.” - Cardiology Specialist, 15 years experience

“In nephrology practice, furosemide provides crucial fluid management for our dialysis patients and those with nephrotic syndrome. The ability to use both oral and IV formulations allows for seamless transition between care settings.” - Nephrologist, 12 years experience

“While extremely effective, furosemide requires careful monitoring of electrolytes, particularly in elderly patients. Its potency demands respect and thorough patient education about signs of dehydration.” - Internal Medicine Physician, 20 years experience

“The rapid action of IV furosemide in pulmonary edema cases can be literally life-saving. However, we always administer slowly to minimize ototoxicity risk.” - Emergency Medicine Physician, 8 years experience