A nurse is preparing to administer the correct volume of amoxicillin for a pediatric patient. If the dose on hand were 250 mg per 5 mL and the ordered dose is 100 mg, what volume is required for the dose?

• A. 2 mL
• B. 3 mL
• C. 4 mL
• D. 5 mL

Answer: (A)

You determine volume from the drug’s concentration. If 250 mg is in 5 mL, the concentration is 50 mg per mL. To deliver 100 mg, solve for volume: 50 mg/mL × volume = 100 mg, so volume = 100 ÷ 50 = 2 mL. The required volume is 2 mL, since 2 mL × 50 mg/mL = 100 mg. For reference, 3 mL would be 150 mg, 4 mL would be 200 mg, and 5 mL would be 250 mg.