What is the recommended dosage of Lasix (furosemide) for a 5-month-old patient?

Furosemide Dosing for a 5-Month-Old Patient

The recommended dosage of Lasix (furosemide) for a 5-month-old patient is 2 mg/kg body weight given as a single oral dose, which may be increased by 1-2 mg/kg no sooner than 6-8 hours after the previous dose if the diuretic response is not satisfactory. 1

Dosing Guidelines

The FDA-approved dosing for pediatric patients provides specific guidance:

• Initial dose: 2 mg/kg body weight as a single oral dose 1
• If diuretic response is inadequate: May increase by 1-2 mg/kg no sooner than 6-8 hours after previous dose 1
• Maximum recommended dose: Should not exceed 6 mg/kg body weight 1

For a 5-month-old infant with edema requiring diuretic therapy, the dosing approach should follow these parameters:

• For mild to moderate edema: 0.5-2 mg/kg per dose up to six times daily 2
• For severe edema: Can use up to 10 mg/kg/day, but this maximum should only be used in severe cases 2
• High doses (>6 mg/kg/day) should not be given for periods longer than 1 week 2

Administration Considerations

• Oral furosemide can be administered without regard to meals, though giving with meals may improve gastrointestinal tolerability 1
• For maintenance therapy in infants, the dose should be adjusted to the minimum effective level 1
• In infants with reasonably normal renal function, a steep dose-response curve has been observed with 1 mg/kg IV dosing, suggesting higher doses may not significantly increase diuretic response 3

Monitoring Requirements

When administering furosemide to a 5-month-old infant, careful monitoring is essential:

• Regular assessment of hydration status, edema, and weight 2
• Monitor for electrolyte abnormalities, particularly hypokalemia, hyponatremia, and hypochloremic alkalosis 2
• Assess urine output and renal function 2
• Blood pressure monitoring is crucial as furosemide should be avoided in hypotensive or hypovolemic patients 2

Potential Complications and Cautions

• Long-term use of furosemide in infants (≥2 mg/kg/day for ≥12 days) has been associated with renal calcifications 4
• Infants receiving long-term furosemide may develop hypercalciuria (10-20 times normal) 4
• If long-term therapy is required, consider adding a thiazide diuretic which can reduce calcium excretion and help prevent renal calcifications 4
• Furosemide must be stopped immediately in case of anuria 2
• High doses or rapid administration increase risk of ototoxicity 2

Special Considerations

For infants with specific conditions:

• Patients with cystic fibrosis may have a more pronounced diuretic response to lower doses 3
• In acute renal failure, total daily dose should not exceed 100 mg 3
• For infants with chronic lung disease, furosemide may help manage associated bronchoconstriction 3

By following these guidelines and carefully monitoring the infant's response, furosemide can be safely and effectively administered to a 5-month-old patient requiring diuretic therapy.