A prescriber orders 75 mg IV. The vial contains 150 mg in 3 mL. How many milliliters should be administered?

A prescriber orders 75 mg IV. The vial contains 150 mg in 3 mL. How many milliliters should be administered?

• A. 0.75 mL
• B. 2 mL
• C. 3 mL
• D. 1.5 mL

Answer: (D)

The key idea is converting concentration to a usable dose. The vial has 150 mg in 3 mL, so the concentration is 150 mg ÷ 3 mL = 50 mg per mL. To get a 75 mg dose, divide by the concentration: 75 mg ÷ 50 mg/mL = 1.5 mL. So you should administer 1.5 mL. As a quick check, 0.75 mL would deliver about 37.5 mg, 2 mL would deliver 100 mg, and 3 mL would deliver 150 mg, confirming 1.5 mL is correct.

The key idea is converting concentration to a usable dose. The vial has 150 mg in 3 mL, so the concentration is 150 mg ÷ 3 mL = 50 mg per mL. To get a 75 mg dose, divide by the concentration: 75 mg ÷ 50 mg/mL = 1.5 mL. So you should administer 1.5 mL. As a quick check, 0.75 mL would deliver about 37.5 mg, 2 mL would deliver 100 mg, and 3 mL would deliver 150 mg, confirming 1.5 mL is correct.