Worked example

Reconstitution — practice problem 12

The prescriber orders 50 mg of cefazolin IV. The vial directs: add 10 mL of diluent to yield 50 mg/mL.

Ordered dose50 mg
After reconstitution50 mg/mL
Diluent10 mL

How many milliliters should the nurse draw up?

Answer: 1 mL

Step-by-step solution

1. Read the concentration after reconstitution
Add 10 mL diluent → 50 mg per 1 mL
2. Set up dimensional analysis so mg cancels
50 mg × ( 1 mL ÷ 50 mg )
3. Cancel mg and solve
= 50 ÷ 50 mL
= 1 mL

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