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MedTestBankDosage Calculation for Nursing

Pediatric Safe Dose Range Calculator

Check whether a pediatric order is within the safe dose range in mg/kg/day or mg/kg/dose, the way you are asked to on nursing exams.

mg/kg
mg/kg
mg

Enter the values: the answer and every step appear here as you type.

Formula

Safe range = low mg/kg × weight (kg) to high mg/kg × weight (kg)

Ordered per day = dose ordered × number of doses per day

Compare the ordered amount with the safe range

How to calculate it step by step

  1. Convert the child's weight to kg (lb ÷ 2.2).
  2. Multiply the low and the high end of the reference range by the weight to get the safe range.
  3. If the range is per day, multiply the ordered dose by the number of doses per day; if it is per dose, compare the single dose.
  4. If the order is within the range, it is safe to give. If it is above or below, hold the dose and contact the prescriber.

Worked examples

Example 1. A child weighing 18.4 kg has an order for ibuprofen 220 mg PO every 6 hours. The drug reference gives a safe range of 5–10 mg/kg/dose. Is the order safe?

  1. Safe range per dose: 5–10 mg/kg × 18.4 kg = 92–184 mg.
  2. Ordered: 220 mg per dose.
  3. The order is above the safe range: hold it and contact the prescriber.

Answer: Unsafe: above the range

Example 2. A child weighing 20.3 kg has an order for ampicillin 400 mg IV every 6 hours. The drug reference gives a safe range of 100–200 mg/kg/day. Is the order safe?

  1. Safe range: 100–200 mg/kg/day × 20.3 kg = 2,030–4,060 mg/day.
  2. Ordered: 400 mg × 4 doses = 1,600 mg/day.
  3. The order is below the safe range: it may not be effective; contact the prescriber.

Answer: Unsafe: below the range

Rounding

Round the weight to the tenth of a kg and the range limits to the tenth of a mg.

Common mistakes

  • Comparing a single dose with a daily range.
  • Converting the frequency wrongly: every 6 hours is 4 doses a day, every 8 hours is 3, every 12 hours is 2.
  • Ignoring an order below the range: an underdose can leave an infection or pain untreated.

Nursing safety points

  • Never give a dose outside the safe range. Hold it, contact the prescriber, and document the conversation.
  • Check the maximum single dose and the maximum daily dose as well as the mg/kg range.
  • Use a current pediatric drug reference: ranges depend on the drug, the indication and the age.

Frequently asked questions

How do you know if a pediatric dose is safe?

Calculate the safe range from the child's weight in kg and the reference range, then compare it with what is ordered over the same period. For an 18 kg child and a range of 20–40 mg/kg/day, the safe range is 360–720 mg/day; 250 mg every 8 hours is 750 mg/day, which is above the range.

What should the nurse do if a dose is not safe?

Hold the medication, contact the prescriber to clarify the order, and document. Do not change the dose yourself.