Section 1: Calculating the Total Amount of Drug Present
If you know the size of a single dose and you know how many doses are needed, then you can calculate the total amount of drug needed.
A patient is given 15 tablets, each tablet containing 30 mg of drug A. What is the total amount of drug A present in the tablets?
The total amount of drug A present is 450 milligrams.
EITHER:
If each tablet contains 30 mg of drug A and there are 15 tablets:
Total amount of drug A present must be 30 x 15 mg.
The total amount of drug A present is 450 milligrams.
OR USING THE EQUATION:
Total amount of drug = Size of Single Dose x Number of Doses
Total amount of drug A = 30 x 15 milligrams
Total amount of drug A = 450 milligrams
A patient needs enough solution for 20 doses. If each dose is 5 ml, how many ml of solution are needed?
100 ml of solution are needed.
EITHER:
If 20 doses are needed and each dose is 5 ml:
The total amount needed is 20 x 5 ml.
The total amount needed is 100 ml.
OR USING THE EQUATION:
Total Amount = Size of Single Dose x Number of Doses
Total Amount of Solution = 5 x 20 millilitres
Total Amount of Solution = 100 millilitres