Worked example

Oral dose - liquid - practice problem 4

The prescriber orders 625 mg of cephalexin oral suspension. The bottle is labeled 250 mg per 5 mL.

Ordered dose625 mg
Concentration250 mg per 5 mL

How many milliliters should the nurse give?

Answer: 12.5 mL

Step-by-step solution

1. Identify what you have and what you want
Have: 250 mg per 5 mL · Want: 625 mg
2. Set up dimensional analysis so mg cancels
625 mg × ( 5 mL ÷ 250 mg )
3. Cancel mg and solve
= ( 625 × 5 ) ÷ 250 mL
= 12.5 mL

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