A patient is prescribed 0.2 mg/kg; the patient weighs 45 kg. What is the total dose in milligrams?

A patient is prescribed 0.2 mg/kg; the patient weighs 45 kg. What is the total dose in milligrams?

• A. 6 mg
• B. 8 mg
• C. 7 mg
• D. 9 mg

Answer: (D)

Multiply the dose per kilogram by the patient’s weight in kilograms. The order is 0.2 mg/kg and the patient weighs 45 kg, so 0.2 × 45 = 9 mg. Therefore, the total dose is 9 mg. Quick check: 9 mg ÷ 45 kg = 0.2 mg/kg, which matches the prescription. The other total doses would imply different mg/kg doses (for example, 6 mg would be 0.133 mg/kg, 8 mg would be 0.178 mg/kg, etc.), not the given 0.2 mg/kg.

Multiply the dose per kilogram by the patient’s weight in kilograms. The order is 0.2 mg/kg and the patient weighs 45 kg, so 0.2 × 45 = 9 mg. Therefore, the total dose is 9 mg. Quick check: 9 mg ÷ 45 kg = 0.2 mg/kg, which matches the prescription. The other total doses would imply different mg/kg doses (for example, 6 mg would be 0.133 mg/kg, 8 mg would be 0.178 mg/kg, etc.), not the given 0.2 mg/kg.