General Dose Calculations – Number, size of a dose, total quantity of a Drug
A pharmacist should be able to calculate the number of doses that can be made from a given quantity of drug, size of a dose and the total quantity of medication to be dispensed. For determining these variables, the following equation is useful:
$$ No. of Doses = {total \ quantity \over size \ of \ dose}$$
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Solved Problem: Dose of an antibiotic is 100 mg, how many doses are there in 10 g of antibiotic. $$ No. of Doses = {10000 \ mg \over 100 \ mg}$$ Answer: 100 doses |
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Solved Problem: If 100 ml of a cough syrup contains 20 doses, how many teaspoonfuls are there in each dose? $$ 20 = {100 \ ml \over size \ of \ dose}$$ $$ size \ of \ dose = 5 \ ml = 1 \ teaspoon $$ Answer: 1 teaspoon |
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Solved Problem: A pharmacist needs to prepare 70 doses each containing 40 mg of drug, how many grams of drug will he need? $$ 70 = { total \ quantity \over 40 \ mg} = 2800 \ mg$$ Answer: 2.8 g |