Massachusetts Pharmacy Technician License Practice Test

Using Clark's rule, what is the child's dose of a drug for an eight-year-old boy weighing 75 pounds with an adult dose of 400 mg?

1. 150 mg

2. 200 mg

3. 300 mg

4. 100 mg

The correct answer is: 200 mg

To determine the child's dose using Clark's rule, the formula involves the child's weight in pounds compared to a standard adult weight, which is typically set at 150 pounds. Clark's rule is expressed as follows: - Child's dose = (Weight of child in pounds / 150) x Adult dose In this scenario, the child weighs 75 pounds and the adult dose is 400 mg. Plugging the numbers into the formula gives: - Child's dose = (75 / 150) x 400 mg - Child's dose = 0.5 x 400 mg - Child's dose = 200 mg This calculation provides the correct child's dosage based on Clark's rule, demonstrating how the child's weight proportional to the standard adult weight scales down the adult dose appropriately for a safer and more effective pediatric dosing. The chosen answer reflects this calculation accurately.