Worked example

Oral dose - liquid - practice problem 5

The prescriber orders 375 mg of cephalexin oral suspension. The bottle is labeled 125 mg per 5 mL.

Ordered dose375 mg
Concentration125 mg per 5 mL

How many milliliters should the nurse give?

Answer: 15 mL

Step-by-step solution

1. Identify what you have and what you want
Have: 125 mg per 5 mL · Want: 375 mg
2. Set up dimensional analysis so mg cancels
375 mg × ( 5 mL ÷ 125 mg )
3. Cancel mg and solve
= ( 375 × 5 ) ÷ 125 mL
= 15 mL

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