math
posted by melissa on .
A prescription calls for erythromycin 400mg/5ml, dispense 100ml. The dose is 40mg/kg/day and the child weighs 44 pounds. The sig. reads ____tsp qid until gone. What would the tsp dose be? How many days will the prescription last?

44 lb is 20 kg, so the child's dose is 20kg*40(mg/kg day) = 800 mg/day. That would require 10 ml of the solution per day, since 5 ml contains 400 mg of the active ingredient.
A 100 ml bottle would last 100 ml/10 ml/day = 10 days.
I will leave you to convert the 10 ml daily liquid mixture dose to teaspoons (tsp).