Examples · Reconstitution
Worked example
Reconstitution — practice problem 9
The prescriber orders 750 mg of ampicillin IV. The vial directs: add 2.5 mL of diluent to yield 250 mg/mL.
Ordered dose750 mg
After reconstitution250 mg/mL
Diluent2.5 mL
How many milliliters should the nurse draw up?
Answer: 3 mL
Step-by-step solution
1. Read the concentration after reconstitution
Add 2.5 mL diluent → 250 mg per 1 mL
2. Set up dimensional analysis so mg cancels
750 mg × ( 1 mL ÷ 250 mg )
3. Cancel mg and solve
= 750 ÷ 250 mL
= 3 mL
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