A nurse is preparing to administer clindamycin phosphate IM 15 mg/kg/day divided in equal doses every 6 hr to an infant who weighs 21 lb.

A nurse is preparing to administer clindamycin phosphate IM 15 mg/kg/day divided in equal doses every 6 hr to an infant who weighs 21 lb. Available is clindamycin phosphate injection 150 mg/mL. How many mL should the nurse administer per dose? (Round the answer to the nearest hundredth. Use a leading zero if applicable. Do not use a trailing zero.)

The Correct Answer and Explanation is:

To determine the correct dosage of clindamycin phosphate for the infant, follow these steps:

1. Convert the infant’s weight from pounds to kilograms:
   • The infant weighs 21 lb. The conversion factor is 1 kg = 2.20462 lb.
   • Weight in kg=21 lb2.20462≈9.53 kg\text{Weight in kg} = \frac{21 \text{ lb}}{2.20462} \approx 9.53 \text{ kg}Weight in kg=2.2046221 lb​≈9.53 kg
2. Calculate the total daily dose:
   • The ordered dosage is 15 mg/kg/day.
   • Total daily dose=15 mg/kg/day×9.53 kg≈142.95 mg/day\text{Total daily dose} = 15 \text{ mg/kg/day} \times 9.53 \text{ kg} \approx 142.95 \text{ mg/day}Total daily dose=15 mg/kg/day×9.53 kg≈142.95 mg/day
3. Divide the total daily dose into equal doses every 6 hours:
   • Since there are 24 hours in a day and the medication is to be administered every 6 hours, this results in 4 doses per day.
   • Dose per administration=142.95 mg4≈35.74 mg\text{Dose per administration} = \frac{142.95 \text{ mg}}{4} \approx 35.74 \text{ mg}Dose per administration=4142.95 mg​≈35.74 mg
4. Calculate the volume of clindamycin phosphate injection to administer:
   • The available concentration of clindamycin phosphate is 150 mg/mL.
   • To find the volume needed for a single dose, use the formula:
   Volume (mL)=Dose (mg)Concentration (mg/mL)\text{Volume (mL)} = \frac{\text{Dose (mg)}}{\text{Concentration (mg/mL)}}Volume (mL)=Concentration (mg/mL)Dose (mg)​
   • Substituting the values:
   Volume (mL)=35.74 mg150 mg/mL≈0.2383 mL\text{Volume (mL)} = \frac{35.74 \text{ mg}}{150 \text{ mg/mL}} \approx 0.2383 \text{ mL}Volume (mL)=150 mg/mL35.74 mg​≈0.2383 mL
5. Round the answer to the nearest hundredth:
   • Rounding 0.2383 mL gives approximately 0.24 mL.

In summary, the nurse should administer 0.24 mL of clindamycin phosphate per dose. This calculation ensures that the infant receives the appropriate dose based on their weight and the medication’s available concentration, which is crucial in pediatric pharmacotherapy due to the sensitivity of infants to medication dosing. Proper conversions and calculations are essential to avoid underdosing or overdosing, which can lead to inadequate treatment or adverse effects, respectively.