A medication is ordered at 10 mg/hr. The available concentration is 2 mg/mL. What is the infusion rate in mL/hr?

A medication is ordered at 10 mg/hr. The available concentration is 2 mg/mL. What is the infusion rate in mL/hr?

• A. 2 mL/hr
• B. 10 mL/hr
• C. 1.6 mL/hr
• D. 5 mL/hr

Answer: (D)

Infusion rate is found by converting the prescribed dose into a volume using the concentration. The rate in mL per hour equals the dose rate (mg/hr) divided by the concentration (mg/mL). Here, 10 mg/hr ÷ 2 mg/mL = 5 mL/hr. So the infusion should run at 5 mL per hour. If you test other numbers, 2 mL/hr would deliver only 4 mg/hr, 10 mL/hr would deliver 20 mg/hr, and 1.6 mL/hr would deliver 3.2 mg/hr. The math hinges on canceling the mg units, leaving mL/hr.

Infusion rate is found by converting the prescribed dose into a volume using the concentration. The rate in mL per hour equals the dose rate (mg/hr) divided by the concentration (mg/mL). Here, 10 mg/hr ÷ 2 mg/mL = 5 mL/hr. So the infusion should run at 5 mL per hour.

If you test other numbers, 2 mL/hr would deliver only 4 mg/hr, 10 mL/hr would deliver 20 mg/hr, and 1.6 mL/hr would deliver 3.2 mg/hr. The math hinges on canceling the mg units, leaving mL/hr.