A prescription calls for 0.36 mg of a drug that you have in 50 mcg/mL concentration. How many mL do you need?

Question

Can someone answer this in an algebraic expression?

Answer 1

Convert mcg to mg so you are working in the same units throughout the problem.

50 mcg x 1 mg/1000 mcg = 0.050 mg.  So the on-hand drug solution of 50 mcg/ml is = 0.050 mg/ml.

Now, find mls needed to obtain 0.36 mg of drug.

(0.05 mg/ml)(x ml) = 0.36 mg

x ml = 0.36 mg/0.05 mg/ml

x ml = 7.2 ml