Question

A medication order for a 20-lb pediatric patient calls for vancomycin 10mg/kg, to be administered by intravenous infusion. The pharmacy has a 10-mL injection containing 500 mg of vancomycin. The pharmacist adds the correct amount to a 100-mL bag of normal saline solution. (A) How many milliliters of the injection were added and (B) what is the content of vancomycin in the infusion, in mg/mL? The answers are (A) 1.8 mL and (B) 0.89 mg/mL vancomycin. Please show how these problems are solved.

Answer 1

Solution :-

Part a) Converting lb to kg

20 lb * 0.4536 kg /1 lb = 9.072 kg

`now lets calculate the dose needed for the 9.072 kg weight

9.072 kg* 10 mg/kg = 90.72 mg

Now lets calculate the volume of injection in ml needed to deliver 90.72 mg

90.72 mg * 10 ml / 500 mg = 1.8 mL injection

Therefore the answer for the part A is volume of injection added is 1.8 mL

Part b)

Content of vancomycin in the infusion

Total volume = 1.8 ml + 100 ml = 101.8 ml

Amount of vancomycin = 90.72 mg

Therefore

90.72 mg / 101.8 ml = 0.89 mg/ml

Therefore the answer for the part b is 0.89 mg/mL