Starting Dose for Lasix (Furosemide)
The recommended initial dose of furosemide is 20-40 mg given as a single dose, administered intravenously or intramuscularly. 1
Dosing Guidelines by Route of Administration
Intravenous Administration
- Initial dose: 20-40 mg IV given slowly over 1-2 minutes 1
- For acute pulmonary edema: 40 mg IV initially, may increase to 80 mg if satisfactory response not seen within 1 hour 1
- Maximum rate for high-dose IV infusion: should not exceed 4 mg/min 1
Oral Administration
- Initial dose: 20-40 mg as a single dose 2
- For heart failure patients: Starting with 20 mg can produce significant diuretic and natriuretic effects 3
Dosing Considerations for Special Populations
Pediatric Patients
- Initial dose: 1 mg/kg body weight given slowly under close medical supervision 1
- May increase by 1 mg/kg not sooner than 2 hours after previous dose if response is inadequate 1
- Maximum recommended dose: 6 mg/kg body weight 1
- For premature infants: Maximum dose should not exceed 1 mg/kg/day 1
Geriatric Patients
- Dose selection should be cautious, usually starting at the low end of the dosing range 1
Heart Failure Patients
- Initial dose: 20-40 mg IV or oral 2
- For volume-overloaded patients: May increase dose according to renal function and history of chronic diuretic use 2
- Total furosemide dose should remain < 100 mg in the first 6 hours and < 240 mg during the first 24 hours 2
Monitoring and Follow-up
- Assess patients frequently in the initial phase to follow urine output 2
- Monitor for potential adverse effects:
- Electrolyte abnormalities (hypokalaemia, hyponatraemia, hyperuricaemia)
- Hypovolaemia and dehydration
- Neurohormonal activation
- Hypotension following initiation of ACEIs/ARBs 2
Important Clinical Considerations
- Parenteral therapy should be replaced with oral therapy as soon as practical 1
- For refractory cases, combination with thiazide diuretics (e.g., hydrochlorothiazide 25 mg) or aldosterone antagonists (spironolactone, eplerenone 25-50 mg) may be considered 2
- Furosemide is a buffered alkaline solution with a pH of about 9 and may precipitate at pH values below 7 1
- Acid solutions or other parenteral medications must not be administered concurrently in the same infusion 1
Efficacy and Dose Adjustments
- Studies show that even low doses (20 mg) can produce significant diuretic effects in heart failure patients 3
- Dose should be adjusted based on clinical response to achieve maximal therapeutic effect with minimal dose needed 1
- For refractory heart failure, higher doses (≥500 mg/day) may be considered in selected cases, but should be administered cautiously 4
Remember that close medical supervision is necessary when furosemide is given, especially for prolonged periods, and therapy should always be individualized according to patient response.