Worked example

Weight-based dose (mg/kg) — practice problem 5

A patient weighs 30 kg. The prescriber orders cefazolin 3 mg/kg/day divided into 2 equal doses.

Weight30 kg
Ordered3 mg/kg/day
Frequency2 doses/day

How many mg is each dose?

Answer: 45 mg per dose

Step-by-step solution

1. Multiply weight by the ordered mg/kg/day
30 kg × ( 3 mg ÷ 1 kg )
= 90 mg/day
2. Divide the daily dose into 2 equal doses
90 mg/day ÷ 2 doses
= 45 mg per dose

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