Question

You want to give 5mg/kg of ampicillin Q8HR to a child weighing 65 pounds. If there is 25mg/ml on hand, how many total mls will you give in 24 hours?

Choose one answer.

a. 18 mls
b. 17.7 mls
c. 17.76 mls
d. 17.4 mls

Answer 1

To calculate the total mls of ampicillin given to a
`65-pound` child over 24 hours at a dosage of
`5mg/kg Q8HR` and
`25mg/ml` concentration, you first convert the child's weight to kilograms, calculate the dose per administration and determine the volume for one administration. Multiplying this volume by the number of administrations in
`24 hours`, the total volume administered is
`17.7 mls`.

Step-by-step explanation:

To determine how many total milliliters (mls) of ampicillin should be administered to a child weighing
`65 pounds` over
`24 hours`, given a dosage of
`5mg/kg` every eight hours (Q8HR) and a concentration of
`25mg/ml`.

follow these steps:

• Convert the child's weight from pounds to kilograms using the conversion factor
  `1 kg = 2.20462 pounds`.
• Multiply the child's weight in kilograms by the dosage
  `(5mg/kg)` to find the total dosage per administration.
• Divide the total dosage per administration by the concentration of the medicine
  `(25mg/ml)` to determine the volume to be administered each time.
• Since the medication is to be administered every
  `8 hours`, calculate the total number of administrations over
  `24 hours`.
• Multiply the volume per administration by the total number of administrations to get the total volume for
  `24 hours.`

First, convert the child's weight:

`65 pounds × (1 kg / 2.20462 pounds) = 29.4835 kg (rounded to four decimal places).`

Next, calculate the dosage per administration:

`29.4835 kg × 5 mg/kg = 147.4175 mg`.

Then find the volume for one administration:

`147.4175 mg ÷ 25 mg/ml = 5.8967 ml` (rounded to four decimal places).

The child receives the medication Q8HR, which is three times per day, so the total volume for
`24 hours` is:

`5.8967 ml × 3 = 17.7 mls` (rounded to one decimal place).

Therefore, the correct choice is (b)
`17.7 mls.`