A client has an order for 200 mg of cimetidine IM. The vial contains 300 mg/2 mL. How many milliliters should be administered?

A client has an order for 200 mg of cimetidine IM. The vial contains 300 mg/2 mL. How many milliliters should be administered?

• A. 0.75
• B. 0.6
• C. 1.3
• D. 1.5

Answer: (C)

Calculating how much to inject from a labeled solution starts with the concentration. The vial has 300 mg in 2 mL, which is 150 mg per mL. To deliver 200 mg, you need Volume = 200 mg ÷ 150 mg/mL ≈ 1.33 mL. In practice, this is rounded to a convenient dose, and 1.3 mL is the closest standard measure, delivering about 195 mg (1.3 mL × 150 mg/mL). A larger volume like 1.5 mL would provide 225 mg, while smaller volumes such as 0.75 or 0.6 mL would deliver far less than 200 mg. So 1.3 mL is the best practical answer.

Calculating how much to inject from a labeled solution starts with the concentration. The vial has 300 mg in 2 mL, which is 150 mg per mL. To deliver 200 mg, you need Volume = 200 mg ÷ 150 mg/mL ≈ 1.33 mL. In practice, this is rounded to a convenient dose, and 1.3 mL is the closest standard measure, delivering about 195 mg (1.3 mL × 150 mg/mL). A larger volume like 1.5 mL would provide 225 mg, while smaller volumes such as 0.75 or 0.6 mL would deliver far less than 200 mg. So 1.3 mL is the best practical answer.