Lidocaine concentration in mg/mL for 400 mg in 250 mL is which of the following?

Lidocaine concentration in mg/mL for 400 mg in 250 mL is which of the following?

• A. 0.4 mg/mL
• B. 1.6 mg/mL
• C. 4 mg/mL
• D. 16 mg/mL

Answer: (B)

Concentration is found by dividing the total amount of drug by the total volume it’s in. For 400 mg in 250 mL, divide 400 by 250 to get 1.6 mg per mL. That matches the given total when you multiply back: 1.6 mg/mL × 250 mL = 400 mg. The other numbers would require different total amounts in the same volume (e.g., 0.4 mg/mL would be 100 mg in 250 mL; 4 mg/mL would be 1000 mg in 250 mL; 16 mg/mL would be 4000 mg in 250 mL).

Concentration is found by dividing the total amount of drug by the total volume it’s in. For 400 mg in 250 mL, divide 400 by 250 to get 1.6 mg per mL. That matches the given total when you multiply back: 1.6 mg/mL × 250 mL = 400 mg. The other numbers would require different total amounts in the same volume (e.g., 0.4 mg/mL would be 100 mg in 250 mL; 4 mg/mL would be 1000 mg in 250 mL; 16 mg/mL would be 4000 mg in 250 mL).