Examples · Reconstitution
Worked example
Reconstitution — practice problem 5
The prescriber orders 250 mg of ceftriaxone IV. The vial directs: add 2.5 mL of diluent to yield 100 mg/mL.
Ordered dose250 mg
After reconstitution100 mg/mL
Diluent2.5 mL
How many milliliters should the nurse draw up?
Answer: 2.5 mL
Step-by-step solution
1. Read the concentration after reconstitution
Add 2.5 mL diluent → 100 mg per 1 mL
2. Set up dimensional analysis so mg cancels
250 mg × ( 1 mL ÷ 100 mg )
3. Cancel mg and solve
= 250 ÷ 100 mL
= 2.5 mL
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