A medication is ordered at 0.8 mg/kg. Patient weight is 55 kg. What is the dose?

A medication is ordered at 0.8 mg/kg. Patient weight is 55 kg. What is the dose?

• A. 22 mg
• B. 44 mg
• C. 55 mg
• D. 60 mg

Answer: (B)

Dosing with mg/kg means multiply the prescribed dose per kilogram by the patient’s weight in kilograms to get the total milligrams to give. Here, 0.8 mg/kg × 55 kg equals 44 mg (0.8 × 55 = 44; think 0.8 × 50 = 40 and 0.8 × 5 = 4, add up to 44). So the correct total dose is 44 mg. The other values would correspond to different per-kilogram doses: 22 mg would be 0.4 mg/kg, 55 mg would be 1 mg/kg, and 60 mg would be about 1.09 mg/kg, which are not the prescribed 0.8 mg/kg for this patient.

Dosing with mg/kg means multiply the prescribed dose per kilogram by the patient’s weight in kilograms to get the total milligrams to give. Here, 0.8 mg/kg × 55 kg equals 44 mg (0.8 × 55 = 44; think 0.8 × 50 = 40 and 0.8 × 5 = 4, add up to 44). So the correct total dose is 44 mg. The other values would correspond to different per-kilogram doses: 22 mg would be 0.4 mg/kg, 55 mg would be 1 mg/kg, and 60 mg would be about 1.09 mg/kg, which are not the prescribed 0.8 mg/kg for this patient.