Safe dose range for each 8 hour dose?

Question

The recommended dosage of amoxicillin is 20 to 40 mg/kg/day divided in equal doses q8 h. The medication is supplied as 50 mg/mL oral suspension. The child weighs 72 pounds

 Calculate the safe dose range for each 8-hour dose. _______________________

(Type in number, then a space, then hyphen, then space, then number.)

AND keep your numbers to the hundredth)

Answer 1

First, convert weight from lbs to kg: 72 lbs x 1 kg/2.2 lbs = 32.7 kg

It would be easiest to do the calculation twice: once using 20 mg/kg/day and the other using 40 mg/kg/day

20 mg/kg/day

20 mg/kg-day x 32.7 kg = 654 mg/day. This is to be divided into 3 equal doses since q 8 hr means 3 x a day

654 mg/day /3 = 218 mg per 8 hr dose

218 mg/dose x 1 ml/50 mg = 4.36 ml per 8 hr dose

40 mg/kg/day

Repeat above calculations using 40 mg/kg/day. Answer should be 2x that calculated for 20 mg/kg/day.

436 mg per 8 hr dose

8.72 ml per 8 hr dose