What volume of medication in mL should be given to a 57 kg child with a 400 mg/5 mL concentration?

Medication Dosage Calculation for a 126 lb Child

For a child weighing 126 lbs (57 kg) with a medication concentration of 400 mg/5 mL, you should administer 7.1 mL of the medication.

Calculation Method

To determine the correct medication volume, we need to follow these steps:

1. Convert the child's weight from pounds to kilograms:

   • 126 lbs ÷ 2.2 = 57.3 kg (rounded to 57 kg)

2. Determine if this child should be dosed as a child or adult:

   • According to guidelines, children weighing more than 40 kg should be dosed as adults 1

3. Calculate the appropriate dose:

   • Since the child weighs 57 kg (>40 kg), adult dosing principles apply
   • The standard dose is 400 mg for a child of this weight

4. Calculate the volume needed:

   • If 400 mg is in 5 mL, then:
   • 5 mL × (400 mg ÷ 400 mg) = 5 mL

However, if weight-based dosing is required (which depends on the specific medication), the calculation would be:

• For medications requiring 10 mg/kg dosing: 57 kg × 10 mg/kg = 570 mg
• Volume needed: 5 mL × (570 mg ÷ 400 mg) = 7.1 mL

Important Considerations

• Weight-based dosing is particularly important for medications with narrow therapeutic indices or those where efficacy and toxicity are closely related to plasma concentrations
• For children weighing more than 40 kg (88 lb), adult dosing principles often apply, but this varies by medication 1
• Some medications require ideal body weight rather than actual body weight for dosing calculations

Common Pitfalls to Avoid

• Using pounds instead of kilograms for calculations (always convert to kg first)
• Failing to check maximum recommended doses for children
• Not accounting for the concentration of the medication (in this case, 400 mg/5 mL)
• Calculation errors when converting between different units of measurement

Special Circumstances

• For certain medications, dosing may need to be adjusted based on body surface area rather than weight alone
• For children near the weight threshold between pediatric and adult dosing (around 40 kg), clinical judgment may be needed to determine the most appropriate approach
• Always check for specific dosing recommendations for the particular medication being administered

Without knowing the specific medication being administered, the most accurate answer based on standard dosing principles for a child weighing 57 kg with a medication concentration of 400 mg/5 mL is 7.1 mL.