An order is received for Principen (ampicillin) 25 mg/kg IV for a toddler who weighs 22 lb. The dose is to be infused over 30 minutes. The ampicillin dose arrives from the pharmacy prepared in 50 mL of solution.
How many milliliters per hour should be administered?
A.
25 mL/hr
B.
50 mL/hr
C.
100 mL/hr
D.
10 mL/hr
The Correct Answer and Explanation is:
To determine how many milliliters per hour should be administered for the toddler, follow these steps:
1. Convert the Toddler’s Weight from Pounds to Kilograms
The weight of the toddler is given as 22 pounds. First, convert this weight into kilograms because the dosage of ampicillin is provided in mg/kg.
1 pound = 0.453592 kilograms22 lb×0.453592 kg/lb=9.979 kg≈10 kg22 \, \text{lb} \times 0.453592 \, \text{kg/lb} = 9.979 \, \text{kg} \approx 10 \, \text{kg}22lb×0.453592kg/lb=9.979kg≈10kg
2. Calculate the Total Dose of Ampicillin
The prescribed dose is 25 mg/kg. Multiply this dose by the toddler’s weight in kilograms:25 mg/kg×10 kg=250 mg25 \, \text{mg/kg} \times 10 \, \text{kg} = 250 \, \text{mg}25mg/kg×10kg=250mg
3. Determine the Infusion Rate
The prepared ampicillin solution arrives in 50 mL. The total dose (250 mg) is contained in these 50 mL. The medication needs to be infused over 30 minutes.
First, convert the infusion time from minutes to hours:30 minutes=0.5 hours30 \, \text{minutes} = 0.5 \, \text{hours}30minutes=0.5hours
To find the infusion rate in mL per hour, use the formula:Infusion Rate=Total VolumeInfusion Time (hours)\text{Infusion Rate} = \frac{\text{Total Volume}}{\text{Infusion Time (hours)}}Infusion Rate=Infusion Time (hours)Total Volume Infusion Rate=50 mL0.5 hours=100 mL/hr\text{Infusion Rate} = \frac{50 \, \text{mL}}{0.5 \, \text{hours}} = 100 \, \text{mL/hr}Infusion Rate=0.5hours50mL=100mL/hr
Conclusion
The infusion rate required is 100 mL per hour.
Correct Answer: C. 100 mL/hr
Explanation
To ensure proper dosing, the medication must be administered at the correct infusion rate based on the prepared volume and the infusion time. By converting the infusion time into hours and calculating the rate based on the total volume of solution, we can determine the correct rate for administration. In this case, to administer 50 mL over 30 minutes, the correct rate is 100 mL per hour. This ensures that the toddler receives the full dose of ampicillin over the prescribed time, maintaining appropriate therapeutic levels of the medication.