Worked example

Reconstitution — practice problem 8

The prescriber orders 150 mg of cefazolin IV. The vial directs: add 10 mL of diluent to yield 50 mg/mL.

Ordered dose150 mg
After reconstitution50 mg/mL
Diluent10 mL

How many milliliters should the nurse draw up?

Answer: 3 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
150 mg × ( 1 mL ÷ 50 mg )
3. Cancel mg and solve
= 150 ÷ 50 mL
= 3 mL

More reconstitution examples