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: Dilling's rule for pediatric dosing is \( \text{Child's Dose} = \frac{\text{Age}}{20} \times \text{Adult Dose} \).
Step 2: Substitute age = 12 years and adult dose = 200 mg: \( \frac{12}{20} \times 200 \).
Step 3: Simplify: \( \frac{12}{20} = 0.6 \), so \( 0.6 \times 200 = 120 \).
\[ \boxed{120 \text{ mg}} \]

Answer 2

Instead of applying the age-over-20 formula directly, we can reason through this using a unitary/proportional approach: Dilling's rule effectively means the adult dose is divided evenly across 20 reference years, and a child receives one unit of that dose per year of age.

1. Finding the per-year share: If the full adult dose of 200 mg corresponds to 20 reference years, then each year of age corresponds to \( \frac{200}{20} = 10 \) mg of dose.
2. Scaling to the child's age: The child in question is 12 years old, so the dose is \( 12 \times 10 = 120 \) mg.
3. Checking against the options: Among 100 mg, 150 mg, 120 mg and 80 mg, only 120 mg matches this proportional build-up from a 10 mg-per-year rate.

Building the dose up year by year from the adult reference gives the same result as before.

Hence, the correct answer is 120mg.