An IV infusion contains 750 mg of a drug in 75 mL and must be delivered over 90 minutes. What is the rate in mL/hour?

An IV infusion contains 750 mg of a drug in 75 mL and must be delivered over 90 minutes. What is the rate in mL/hour?

• A. 25 mL/hr
• B. 50 mL/hr
• C. 75 mL/hr
• D. 100 mL/hr

Answer: (B)

Infusion rate is found by dividing the total volume by the total time. Convert 90 minutes to hours: 90 minutes is 1.5 hours. Then 75 mL ÷ 1.5 h = 50 mL/hour. So the delivery rate is 50 mL/hour. The amount of drug (750 mg) sets the concentration (750 mg in 75 mL = 10 mg/mL), but does not change the mL/hour rate. If you needed mg/hour, that concentration would matter (50 mL/hour × 10 mg/mL = 500 mg/hour).

Infusion rate is found by dividing the total volume by the total time. Convert 90 minutes to hours: 90 minutes is 1.5 hours. Then 75 mL ÷ 1.5 h = 50 mL/hour. So the delivery rate is 50 mL/hour. The amount of drug (750 mg) sets the concentration (750 mg in 75 mL = 10 mg/mL), but does not change the mL/hour rate. If you needed mg/hour, that concentration would matter (50 mL/hour × 10 mg/mL = 500 mg/hour).