Examples · Reconstitution
Worked example
Reconstitution - practice problem 10
The prescriber orders 500 mg of ampicillin IM. A 1 g vial directs: add 3.5 mL of diluent to yield 250 mg/mL.
Ordered dose500 mg
Vial1 g
Diluent3.5 mL
After reconstitution250 mg/mL
How many milliliters should the nurse draw up?
Answer: 2 mL
Step-by-step solution
1. Read the concentration after reconstitution
Add 3.5 mL diluent → 250 mg per 1 mL
2. Set up dimensional analysis so mg cancels
500 mg × ( 1 mL ÷ 250 mg )
3. Cancel mg and solve
= 500 ÷ 250 mL
= 2 mL
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