Calculation of Doses for Children

Young’s Rule = expression used to determine a drug dosage for children. The correct dosage is calculated by dividing the child’s age by an amount equal to the child’s age plus 12 and then multiplying by the usual adult dose.

Formula:

Adult Dose * (Age ÷ (Age+12)) = Child’s Dose

Example:

If the drug dose for an adult is 750 mg, how much should a 10 year old child receive?

Adult Dose * (Age ÷ (Age+12)) = Child’s Dose

750 mg * (10 ÷ (10+12)) = Child’s Dose

750 mg * (10 ÷ 22) = Child’s Dose

750 mg * 0.4545 = Child’s Dose

340.91 mg = Child’s Dose

Clark’s Rule = expression used to determine a drug dosage for children. The procedure is to take the child’s weight in pounds, divide by 150 lb, and multiply the fractional result by the adult dose to find the equivalent child dosage.

Formula:

Adult Dose * (Child’s Weight in pounds ÷ 150) = Childs Dose

Note: Child’s weight must be in lbs and not kg

Example:

If the drug dose for an adult is 750 mg, how much should a 50 lb child receive?

Adult Dose * (Child’s Weight in pounds ÷ 150) = Childs Dose

750 mg * (50 ÷ 150) = Child’s Dose

750 mg * (0.33333) = Child’s Dose

250 mg = Child’s Dose