# Clark's Rule

by Confused

"An 8 year old girl was prescribed a particular drug with an adult dosage of 2.75mg/kg. The recommended dosage for children 5-12 years old is 80% of the adult dosage.If the child weighs 75 lbs, how much would her dosage be?"

Would you use Clark's rule for the question? And if so, how would you go about that with kg/lbs? I'm not sure how/if you convert the kgs to lbs or vice-versa for this equation. Thank you.

### Comments for Clark's Rule

 Children's dosage by: Anonymous NO, you would not use Clark's or Young's rule. Just use the directions right in the question.All you have to do is figure out what the dosage would be (if it were for an adult), and then multiply it by 80%.1. Convert weight to Kg 75Lb = 34Kg2. Figure adult dosage 2.75(mg)/(34)kg = 93.5mg 3. Multiply that by 80%93.5mg X 0.80 = 74.8mgIMPORTANT: If the question never mentions Clarks / Young's rule, then you probably wont be using it for the problem.

 Confused. by: Anonymous What happens to the formula for clark's rule: Adult dose X (weight/150)?

 Children's Dosage answer kind off or something by: Brittney W.- Pharmacy Technician 2015 The person who answered with children's dosage, I don't understand where you got that 93. something from but I ended up with the same answer of 74.8mg.Here's what I did:Found the weight in kg75÷2.2=34.09 (rounded 34kg)Then found 80% of 2.75mg/kg2.75×.80=2.2mgThen multiplied the 2.2 by the weight in kg2.2mg×34kg=74.8mgThink I did everything right???ANSWER: 74.8mg