Worked example

Reconstitution - practice problem 10

The prescriber orders 1000 mg of ampicillin IV. The vial directs: add 2 mL of diluent to yield 125 mg/mL.

Ordered dose1000 mg
After reconstitution125 mg/mL
Diluent2 mL

How many milliliters should the nurse draw up?

Answer: 8 mL

Step-by-step solution

1. Read the concentration after reconstitution
Add 2 mL diluent → 125 mg per 1 mL
2. Set up dimensional analysis so mg cancels
1000 mg × ( 1 mL ÷ 125 mg )
3. Cancel mg and solve
= 1000 ÷ 125 mL
= 8 mL

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