SOLVED. The following information is on the label of a 500 mg/vial cefazolin for injection USP: “For IM administration: Add 2 mL of sterile water for injection. SHAKE WELL to dissolve. Withdraw entire contents. Provides an approximate volume of 2.2 mL (225 mg/mL). For IV administration: See package insert.” The nurse is to administer cefazolin 500 mg IM every 12 hr. How many mL of sterile water for injection will the nurse add to the vial? What is the resulting dosage strength? How many mL will the nurse administer?