Worked example

Reconstitution - practice problem 2

The prescriber orders 2000 mg of ampicillin IV. The vial directs: add 2 mL of diluent to yield 125 mg/mL.

Ordered dose2000 mg

After reconstitution125 mg/mL

Diluent2 mL

How many milliliters should the nurse draw up?

Answer: 16 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

2000 mg × ( 1 mL ÷ 125 mg )

3. Cancel mg and solve

= 2000 ÷ 125 mL

= 16 mL