100 mL of fluid containing vancomycin 400 mg has been added to a burette. The infusion is to be given over 45 minutes. What is the required pump setting in mL/h?

• A. 120 mL/h
• B. 133 mL/h
• C. 125 mL/h
• D. 140 mL/h

Answer: (B)

Infusion rate is the volume delivered per unit time. To find mL per hour, take the total volume and divide by the infusion time in hours. 45 minutes is 0.75 hours, so 100 mL ÷ 0.75 h = 133.33 mL/h, which rounds to 133 mL/h. The amount of drug (400 mg) inside the 100 mL doesn’t change the pump setting here because the instruction is to deliver the entire volume in 45 minutes. Therefore the appropriate pump rate is 133 mL/h.