Worked example

Oral dose — tablets — practice problem 9

The prescriber orders 500 mg of metformin PO. The pharmacy stocks metformin in 500 mg tablets.

Ordered dose500 mg
On hand500 mg per tablet

How many tablets should the nurse give?

Answer: 1 tablet

Step-by-step solution

1. Identify what you have and what you want
Have: 500 mg per tablet · Want: 500 mg
2. Set up dimensional analysis so mg cancels
500 mg × ( 1 tablet ÷ 500 mg )
3. Cancel mg and solve
= ( 500 × 1 ) ÷ 500 tablet
= 1 tablet

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