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?
25 mL/hr
50 mL/hr
100 mL/hr
10 mL/hr
The Correct Answer is C
To find the milliliters per hour, you need to calculate the following:
- The patient's weight in kilograms
- The dose of Principen in milligrams
- The infusion rate in milliliters per hour using the formula: Infusion rate (mL/h) = (Total volume (mL) x Flow factor (gt/mL)) / Time (min) x 60 min/h
First, convert the patient's weight from pounds to kilograms by dividing by 2.2:
22 lb / 2.2 = 10 kg
Next, multiply the patient's weight by the dose of Principen per kilogram to get the total dose in milligrams:
10 kg x 25 mg/kg = 250 mg
Then, use the formula for infusion rate to find how many milliliters per hour the IV pump should deliver:
Infusion rate (mL/h) = (Total volume (mL) x Flow factor (gt/mL)) / Time (min) x 60 min/h
Since the medication is prepared in 50 mL of solution and the infusion time is 30 minutes, plug in these values into the formula:
Infusion rate (mL/h) = (50 mL x 1 gt/mL) / 30 min x 60 min/h
Simplify and solve for the infusion rate:
Infusion rate (mL/h) = 100 mL/h
Therefore, the nurse should administer **100 mL/h** to infuse Principen 250 mg over 30 minutes.

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Related Questions
Correct Answer is B
Explanation
The infusion will be completed at 3:15 p.m.
This answer is correct because it is based on a simple division and addition calculation. The nurse should follow these steps to determine when the infusion will be completed:
1) Convert the volume of the fluid from liters to milliliters by multiplying by 1000, since there are 1000 mL in 1 L. The volume of the fluid is 750 mL.
2) Divide the volume of the fluid by the infusion rate to get the duration of the infusion in hours, as follows:
750 mL / 120 mL/hr = 6.25 hr
Therefore, the infusion will take 6.25 hours to complete.
3) Add the duration of the infusion to the start time of the infusion to get the end time, as follows:
9:00 a.m. + 6:25 = 3:15 p.m.
Therefore, the infusion will be completed at 3:15 p.m.
Correct Answer is C
Explanation
The nurse should add 250 mL of water to the formula to dilute it to half strength.
This answer is correct because it is based on a simple ratio and proportion calculation. The nurse can set up a proportion as follows:
250 mL / 1 = x mL / 0.5
Cross-multiplying and solving for x gives:
x = 500 mL
Therefore, the nurse should add 250 mL of water to the formula to make a total volume of 500 mL, which is half the concentration of the original formula.
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