If a medication is supplied at 5 mg/mL and a 10 mg dose is prescribed, how many milliliters are required?

If a medication is supplied at 5 mg/mL and a 10 mg dose is prescribed, how many milliliters are required?

• A. 1 ml
• B. 2 ml
• C. 3 ml
• D. 4 ml

Answer: (B)

Think of the dose in relation to how much medicine is in each milliliter. If the solution is 5 mg per mL, each mL contains 5 mg. To get a 10 mg dose, divide the desired amount by the concentration: 10 mg ÷ 5 mg/mL = 2 mL. So you would administer 2 milliliters. Quick check: 2 mL × 5 mg/mL = 10 mg, which matches the prescription.

Think of the dose in relation to how much medicine is in each milliliter. If the solution is 5 mg per mL, each mL contains 5 mg. To get a 10 mg dose, divide the desired amount by the concentration: 10 mg ÷ 5 mg/mL = 2 mL. So you would administer 2 milliliters. Quick check: 2 mL × 5 mg/mL = 10 mg, which matches the prescription.