A medication dosage is 0.4 mg/kg per dose for a patient weighing 22 kg. The drug is supplied as 0.8 mg/mL. How many mL per dose?

• A. 5.5 mL
• B. 11 mL
• C. 8 mL
• D. 15 mL

Answer: (B)

Start with the weight-based dose and convert to a volume using the drug’s concentration. Multiply the patient’s weight by the dose per kilogram: 22 kg × 0.4 mg/kg = 8.8 mg per dose. The solution is 0.8 mg per 1 mL, so convert the milligrams to milliliters: 8.8 mg ÷ 0.8 mg/mL = 11 mL per dose. In other words, 11 mL delivers the required 8.8 mg.