A patient is to receive 2000 units of heparin. If the vial is 1000 units per mL, how many mL are needed?

A patient is to receive 2000 units of heparin. If the vial is 1000 units per mL, how many mL are needed?

• A. 1.0
• B. 2.0
• C. 3.0
• D. 4.0

Answer: (B)

When you convert a prescribed amount from units to volume, you use volume = total units ÷ (units per milliliter). If the solution has a concentration of one thousand units per milliliter, each milliliter contains one thousand units. You need two thousand units, which is twice as many as what’s in one milliliter, so you draw twice the volume of one milliliter. That means you should prepare an amount equal to twice one milliliter.

When you convert a prescribed amount from units to volume, you use volume = total units ÷ (units per milliliter). If the solution has a concentration of one thousand units per milliliter, each milliliter contains one thousand units. You need two thousand units, which is twice as many as what’s in one milliliter, so you draw twice the volume of one milliliter. That means you should prepare an amount equal to twice one milliliter.