An infant who weighs 22 pounds receives a prescription for amoxicillin 20 mg/kg/day by mouth in divided doses every 8 hours. The bottle is labeled, “Amoxicillin for Oral Suspension, USP 250 mg per 5 mL.” How many mL should the nurse administer with each dose? (Enter numerical value only. If rounding is necessary, round to the nearest tenth.)
The correct answer and Explanation is :
To determine the correct dosage of amoxicillin for the infant, follow these steps:
1. Convert the Infant’s Weight to Kilograms
The infant weighs 22 pounds. First, convert this weight into kilograms. The conversion factor is 1 pound = 0.453592 kilograms.
[ 22 \text{ pounds} \times 0.453592 \text{ kg/pound} = 9.979 \text{ kg} ]
Rounding to one decimal place, the weight is approximately 10 kg.
2. Calculate the Total Daily Dose
The prescription is for 20 mg of amoxicillin per kilogram of body weight per day. To find the total daily dose for the infant:
[ 20 \text{ mg/kg/day} \times 10 \text{ kg} = 200 \text{ mg/day} ]
3. Determine the Dosage per Administration
The medication is to be administered in divided doses every 8 hours. There are 24 hours in a day, so the number of doses per day is:
[ \frac{24 \text{ hours/day}}{8 \text{ hours/dose}} = 3 \text{ doses/day} ]
Thus, the amount of amoxicillin per dose is:
[ \frac{200 \text{ mg/day}}{3 \text{ doses/day}} = 66.67 \text{ mg/dose} ]
4. Convert the Dosage to mL Using the Concentration
The concentration of the amoxicillin suspension is 250 mg per 5 mL. To find out how many mL are needed to administer 66.67 mg:
First, determine the amount of mg per mL:
[ \frac{250 \text{ mg}}{5 \text{ mL}} = 50 \text{ mg/mL} ]
Now, calculate the volume needed for 66.67 mg:
[ \frac{66.67 \text{ mg}}{50 \text{ mg/mL}} = 1.333 \text{ mL} ]
5. Round to the Nearest Tenth
Rounding 1.333 mL to the nearest tenth gives:
[ 1.3 \text{ mL} ]
Therefore, the nurse should administer 1.3 mL of the amoxicillin suspension with each dose.