A medication is available as a 0.5gm/5mL suspension. How many mL should a nurse administer to provide a 200mg dose?

• A. 0.5
• B. 2
• C. 4
• D. 2.5

Answer: (B)

Start by converting the suspension’s strength to an amount per milliliter. 0.5 g equals 500 mg, and that 500 mg is in 5 mL, so the concentration is 500 mg / 5 mL = 100 mg per mL. To deliver a 200 mg dose, calculate the volume needed: 200 mg ÷ 100 mg/mL = 2 mL. Therefore, administering 2 mL provides 200 mg (2 mL × 100 mg/mL = 200 mg). A quick check confirms the calculation and keeps units consistent (mg and mL).