Worked example

Oral dose — liquid — practice problem 1

The prescriber orders 62.5 mg of ranitidine oral suspension. The bottle is labeled 125 mg per 1 mL.

Ordered dose62.5 mg
Concentration125 mg per 1 mL

How many milliliters should the nurse give?

Answer: 0.5 mL

Step-by-step solution

1. Identify what you have and what you want
Have: 125 mg per 1 mL · Want: 62.5 mg
2. Set up dimensional analysis so mg cancels
62.5 mg × ( 1 mL ÷ 125 mg )
3. Cancel mg and solve
= ( 62.5 × 1 ) ÷ 125 mL
= 0.5 mL

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