A pediatric dose of ceftriaxone is 100 mg/kg/day. The patient weighs 47 pounds. What is the daily dose in milligrams?

A pediatric dose of ceftriaxone is 100 mg/kg/day. The patient weighs 47 pounds. What is the daily dose in milligrams?

• A. 2125 mg
• B. 2100 mg
• C. 2300 mg
• D. 2000 mg

Answer: (A)

Converting weight to the correct unit and applying the per-kilogram dose is the key. Start with 47 pounds and convert to kilograms using 1 kg ≈ 2.2 pounds: 47 ÷ 2.2 ≈ 21.36 kg. Multiply by the daily dose per kilogram: 21.36 kg × 100 mg/kg/day ≈ 2136 mg/day. Among the given options, the value closest to this calculated amount is 2125 mg, which is why that choice is selected. In practice you’d round based on available strengths, but the method and the calculation lead to the ~2136 mg/day result, with 2125 mg being the closest match.

Converting weight to the correct unit and applying the per-kilogram dose is the key. Start with 47 pounds and convert to kilograms using 1 kg ≈ 2.2 pounds: 47 ÷ 2.2 ≈ 21.36 kg. Multiply by the daily dose per kilogram: 21.36 kg × 100 mg/kg/day ≈ 2136 mg/day. Among the given options, the value closest to this calculated amount is 2125 mg, which is why that choice is selected. In practice you’d round based on available strengths, but the method and the calculation lead to the ~2136 mg/day result, with 2125 mg being the closest match.