formulas used in the calculation of child dose

When calculating a child's medication dose, there are several common formulas used, depending on factors like child's weight, age, or body surface area (BSA).

1. Clark’s Rule (based on weight)

This rule estimates the child’s dose from the adult dose, adjusting for the child's weight.

$$\text{Child’s dose}=\frac{\text{Weight of child (in lbs)}}{150}\times \text{Adult dose}$$

This formula assumes the average adult weight is 150 lbs.

2. Young’s Rule (based on age)

This is an age-based formula that calculates the dose based on the child's age in years.

$$\text{Child’s dose}=\frac{\text{Age of child (in years)}}{\text{Age of child}+12}\times \text{Adult dose}$$

3. Fried’s Rule (for infants, based on age)

This is specifically used for infants under the age of 2 years.

$$\text{Infant’s dose}=\frac{\text{Age of infant (in months)}}{150}\times \text{Adult dose}$$

4. Body Surface Area (BSA) Formula

BSA is often used as a more accurate way to calculate a child's dose, particularly for potent drugs like chemotherapy.

$$\text{Child’s dose}=\frac{{\text{BSA of child (m}}^2\text{)}}{1.73}\times \text{Adult dose}$$

Here, 1.73 m² is the average adult BSA.

To calculate the BSA (Mosteller Formula):

$${\text{BSA (m}}^2\text{)}=\sqrt{\frac{\text{Weight (kg)}\times \text{Height (cm)}}{3600}}$$

5. Dilling’s Rule (based on age)

Similar to Young’s Rule, this formula is another age-based approach.

$$\text{Child’s dose}=\frac{\text{Age of child (in years)}}{20}\times \text{Adult dose}$$

These are the common methods used to calculate the appropriate dosage for children. The choice of method depends on the clinical context, the age and weight of the child, and the specific medication being used. Always consult a healthcare professional before calculating and administering any doses.