A physician orders heparin sodium (Liquaemin Sodium) 1,250 units/hour IV. The IV solution contains 25,000 units of heparin in 500 mL. A nurse should set the infusion pump to run at how many mL/hour?

• A. 20
• B. 22
• C. 25
• D. 30

Answer: (C)

When giving a drug by IV with a specific unit-per-hour dose, you convert the solution’s concentration to units per milliliter and then use the rate equation: flow rate (mL/hour) = dose (units/hour) ÷ concentration (units/mL).

The heparin solution has 25,000 units in 500 mL, which is 25,000 ÷ 500 = 50 units per mL. To deliver 1,250 units each hour, the required flow is 1,250 ÷ 50 = 25 mL per hour. Therefore, set the infusion pump to 25 mL/hour. Double-check: 25 mL/hour × 50 units/mL = 1,250 units/hour, confirming the calculation.