PHARMACEUTICAL MATH I PHRA 1209

Dosage calculations can be broken down into three areas:

• calculating the number of doses
• calculating the total amount
• calculating the size of each dose

The formula for dosage is:

Whenever calculating any dosage problem ask the following questions:

• how much of the "active ingredient" do I need ?
• what is the source of this "active ingredient" ?
• what am I trying to find - number of doses, size of each dose or total amount of active ingredient ?

Examples:

How many doses are contained in a 5 gram bottle if the dosage is 25 mg?

source = 5 gram bottle        dose = 25 mg    number doses = ?

1. convert the grams to milligrams (total amount)

2. fill in the formula

What dosage should be administered if 2 grams of a mediation needs to be make into 25 doses?

    source = 2 grams        dose = ? mg    number doses = 25

1. convert the grams to milligrams (total amount)

2. convert the original dose formula (using basic algebra) to solve for the size of each dose

Calculate the volume of a mediation needed to to provide 100 - 10ml doses.

source = ? ml        dose = 10 ml    number doses = 100

convert the original dose formula (using basic algebra) to solve for the total amount