Initial Starting Dose of Lasix (Furosemide) for Heart, Kidney, or Liver Failure
For suspected heart failure, the recommended initial starting dose of furosemide is 20-40 mg orally or intravenously, while for liver failure with ascites, the recommended starting dose is 40 mg orally in combination with 100 mg spironolactone. 1
Heart Failure
- For acute heart failure, the recommended initial dose is a bolus of furosemide 20-40 mg IV at admission 1
- For chronic heart failure, the usual initial oral dose is 20-80 mg given as a single dose 2
- Patients should be monitored frequently in the initial phase to follow urine output; bladder catheterization may be desirable to monitor urinary output and assess treatment response 1
- In patients with evidence of volume overload, the IV furosemide dose may be increased according to renal function and history of chronic oral diuretic use 1
- Total furosemide dose should remain <100 mg in the first 6 hours and <240 mg during the first 24 hours 1
Liver Failure with Ascites
- The usual diuretic regimen consists of single morning doses of oral spironolactone and furosemide, beginning with 100 mg of spironolactone and 40 mg of furosemide 1
- Starting with both drugs appears to be the preferred approach in achieving rapid natriuresis and maintaining normal potassium levels 1
- An alternative approach would be to start with single-agent spironolactone, particularly in the outpatient setting 1
- The doses of both oral diuretics can be increased simultaneously every 3-5 days (maintaining the 100 mg:40 mg ratio) if weight loss and natriuresis are inadequate 1
- Usual maximum doses are 400 mg/day of spironolactone and 160 mg/day of furosemide 1
Kidney Failure
- Patients with parenchymal renal disease may tolerate less spironolactone than usual because of hyperkalemia 1
- Careful dose adjustment is needed based on renal function 1
- Patients with hypotension (SBP <90 mmHg), severe hyponatremia, or acidosis are unlikely to respond to diuretic treatment 1
Important Considerations and Monitoring
- Single morning dosing maximizes compliance 1
- Monitor for potential adverse effects of loop diuretics: 1
- Hypokalaemia, hyponatraemia, hyperuricaemia
- Hypovolaemia and dehydration
- Neurohormonal activation
- Increased hypotension following initiation of ACEI/ARB therapy
Special Populations
- For geriatric patients, dose selection should be cautious, usually starting at the low end of the dosing range 2
- For pediatric patients, the usual initial dose is 2 mg/kg body weight given as a single dose 2
Combination Therapy
- In cases of diuretic resistance, thiazides (hydrochlorothiazide 25 mg) and aldosterone antagonists (spironolactone 25-50 mg) can be used in association with loop diuretics 1
- Combinations in low doses are often more effective with fewer side effects than higher doses of a single drug 1
- Studies have shown that even low doses of furosemide (20 mg) can produce significant diuretic and natriuretic effects in heart failure patients 3
Caution
- Furosemide should be used cautiously in patients with hypotension, as it may worsen hemodynamic status 1
- High doses of diuretics may lead to hypovolemia and hyponatremia, increasing the likelihood of hypotension when initiating ACEIs or ARBs 1
- Alternative treatment options such as IV vasodilators may reduce the need for high-dose diuretic therapy in acute heart failure 1