Question

The adult dose of a drug is 200mg. What is the dose for a child of 12 years as per Dilling’s formula?

• A. 100mg
• B. 150mg
• C. 120mg
• D. 80mg

Hint:

When using Dilling’s formula, remember to apply the child’s age relative to the adult dose to calculate the appropriate pediatric dose.

Answer 1

The Correct Option is C

Step 1: Understanding Dilling’s formula.
Dilling's formula is used to calculate the child's dose based on the adult dose, using the child’s age and the standard age ratio. The formula is: \[ \text{Child's Dose} = \frac{\text{Age of child}}{(Age of child + 12)} \times \text{Adult Dose} \] In this case, the adult dose is 200mg and the child's age is 12 years.
Step 2: Applying the formula.
\[ \text{Child's Dose} = \frac{12}{(12 + 12)} \times 200 = \frac{12}{24} \times 200 = 0.5 \times 200 = 120 \text{ mg} \] Step 3: Conclusion.
The correct answer is (C) 120mg as per Dilling's formula.

Answer 2

Dilling's rule is a pediatric dose-calculation method that scales the adult dose according to the child's age out of a reference age of 20 years, and is expressed as:

\[ \text{Child's Dose} = \frac{\text{Age of child (in years)}}{20} \times \text{Adult Dose} \]

To find the answer, we substitute the child's age and the adult dose into this formula and evaluate each candidate option against the result.

1. 100mg: Substituting a target dose of 100 mg would require the age fraction to equal \( \frac{100}{200} = 0.5 \), meaning \( \frac{\text{age}}{20} = 0.5 \), which implies an age of 10 years - not the 12 years given in the question, so this option does not match.
2. 150mg: This would require \( \frac{\text{age}}{20} = 0.75 \), implying an age of 15 years, which again does not match the stated age of 12.
3. 120mg: Substituting the actual values, \( \frac{12}{20} \times 200 = 0.6 \times 200 = 120 \) mg. This matches exactly what Dilling's rule predicts for a 12-year-old child.
4. 80mg: This would require \( \frac{\text{age}}{20} = 0.4 \), implying an age of 8 years, which does not match either.

Only substituting the actual age of 12 years into Dilling's rule produces a dose that matches one of the candidate options exactly.

Therefore, the correct answer is 120mg.