What is the dose of Lasix (furosemide) in mL for a 1-year-old child weighing 5.55 kg?

Furosemide Dosing for a 1-Year-Old Weighing 5.55 kg

For this 1-year-old child weighing 5.55 kg, the appropriate furosemide dose is 11.1 mg (using the standard 2 mg/kg initial dose), which equals 1.85 mL of the standard 10 mg/mL oral solution, or 2.78 mL if using the 20 mg/5 mL suspension.

Dosing Calculation

• The FDA-approved initial pediatric dose of oral furosemide is 2 mg/kg body weight given as a single dose 1
• For this child: 2 mg/kg × 5.55 kg = 11.1 mg per dose
• If the diuretic response is inadequate, the dose may be increased by 1-2 mg/kg no sooner than 6-8 hours after the previous dose 1
• Maximum dose should not exceed 6 mg/kg body weight (which would be 33.3 mg for this child) 1

Volume Conversion Based on Available Formulations

Standard oral solution (10 mg/mL):

• 11.1 mg ÷ 10 mg/mL = 1.85 mL per dose

Oral suspension (20 mg/5 mL = 4 mg/mL):

• 11.1 mg ÷ 4 mg/mL = 2.78 mL per dose

Administration Guidelines

• The dose should be given as a single administration 1
• If needed, the same dose can be repeated 6-8 hours later 1
• For maintenance therapy, adjust to the minimum effective level once diuresis is achieved 1
• Use an accurate oral syringe for measurement, particularly critical in infants where small volume errors can result in significant dosing errors 2

Important Clinical Considerations

• This child's weight (5.55 kg) is significantly below the expected weight for a 1-year-old (typically 9-11 kg), suggesting possible malnutrition, failure to thrive, or prematurity, which may affect drug response 2
• Monitor for signs of intravascular volume depletion (4.6% incidence) and electrolyte disturbances, particularly hypokalemia (3.6% incidence), which are the most common adverse effects 3
• The diuretic response correlates with urinary furosemide concentration, not plasma levels - a urinary concentration of at least 24.2 ± 10.5 μg/mL is needed for significant diuresis in infants 2
• In infants with reasonably normal renal function, a steep dose-response curve exists at 1 mg/kg IV, suggesting higher doses may not significantly increase diuretic response 2
• Renal function should be monitored as furosemide can compromise glomerular filtration rate through tubuloglomerular feedback activation, particularly if renal function is already impaired 4

Monitoring Parameters

• Urine output should increase within 1-2 hours of oral administration 5
• Watch for excessive fluid loss, hypotension, or signs of dehydration 3
• Electrolytes (particularly potassium) should be monitored, especially with repeated dosing 3
• If no response occurs after the initial dose, consider increasing by 1-2 mg/kg (to 16.65-22.2 mg total) after 6-8 hours 1