A vial contains 5 grams of an antibiotic in 20 mL of solution. If a client is to receive 250 mg, how many mL should the nurse give to the client?

• A. 0.5
• B. 1
• C. 1.5
• D. 1

Answer: (D)

Determining how much to give relies on converting the vial’s strength to milligrams per milliliter and using that to find the volume that delivers the required dose. The vial has 5 grams in 20 mL, which is 5000 mg / 20 mL = 250 mg per mL. To deliver 250 mg, you would administer 250 mg ÷ 250 mg/mL = 1 mL. So the nurse should give 1 mL. If you gave 0.5 mL, that would be 125 mg; 1.5 mL would be 375 mg.