The physician orders thiamine HCL 200 mg IM. The multi-use vial reads 100 mg/mL. How many milliliters should be administered?

The physician orders thiamine HCL 200 mg IM. The multi-use vial reads 100 mg/mL. How many milliliters should be administered?

• A. 2 mL
• B. 1 mL
• C. 0.5 mL
• D. 4 mL

Answer: (A)

When you need a specific dose from a labeled concentration, use volume = dose ÷ concentration. Here, the dose needed is 200 mg and the vial concentration is 100 mg per mL. So the volume required is 200 mg ÷ 100 mg/mL = 2 mL. That means you should administer 2 mL to deliver the full 200 mg dose. If you used 1 mL, you’d only give 100 mg; 0.5 mL would be 50 mg; and 4 mL would be 400 mg, which would be incorrect.

When you need a specific dose from a labeled concentration, use volume = dose ÷ concentration. Here, the dose needed is 200 mg and the vial concentration is 100 mg per mL. So the volume required is 200 mg ÷ 100 mg/mL = 2 mL. That means you should administer 2 mL to deliver the full 200 mg dose.

If you used 1 mL, you’d only give 100 mg; 0.5 mL would be 50 mg; and 4 mL would be 400 mg, which would be incorrect.