Unit 40: Pediatric Dose Calculations

A 6-year-old child needs a medication. The adult dose is 300 mg. Which factor MOST directly determines pediatric dosing in most real-world scenarios?
A. Height
B. Weight (mg/kg)
C. Eye color
D. Blood type

B. Weight (mg/kg)
→ Pediatric dosing is primarily weight-based to avoid over/underdosing

A technician is calculating a pediatric dose using Clark’s Rule. What MUST the child’s weight be in?
A. kg
B. grams
C. pounds
D. ounces

C. pounds
→ Convert kg → lb using × 2.2 before using Clark’s Rule

Which formula is correct for Clark’s Rule?
A. Child dose = Adult dose × (Age / (Age + 12))
B. Child dose = Adult dose × (Weight lb / 150)
C. Child dose = Adult dose ÷ weight
D. Child dose = weight × 2.2

B. Child dose = Adult dose × (Weight lb / 150)

A child weighs 44 lb. Adult dose = 200 mg. What is the pediatric dose (Clark’s Rule)?
A. 58 mg
B. 88 mg
C. 100 mg
D. 132 mg

A. 58 mg
Formula:
Child dose = 200 × (44 / 150) = 200 × 0.293 ≈ 58.6 → wait check
Actually: 200 × 0.293 = 58.6 → correct answer = A

A child weighs 20 kg. Adult dose = 500 mg. What is the FIRST step using Clark’s Rule?
A. Multiply by 2.2
B. Divide by 150
C. Plug into formula
D. Convert to grams

A. Multiply by 2.2
→ Must convert kg → lb first

A child weighs 20 kg. Adult dose = 500 mg. What is the pediatric dose (Clark’s Rule)?
A. 133 mg
B. 147 mg
C. 200 mg
D. 300 mg

B. 147 mg
Step 1: 20 × 2.2 = 44 lb
Step 2: 500 × (44 / 150) = 500 × 0.293 ≈ 147 mg

Which formula is correct for Young’s Rule?
A. Adult dose × (Weight / 150)
B. Adult dose × (Age / (Age + 12))
C. Adult dose ÷ age
D. Age × 12

B. Adult dose × (Age / (Age + 12))

A 4-year-old child needs medication. Adult dose = 240 mg. What is the pediatric dose (Young’s Rule)?
A. 40 mg
B. 60 mg
C. 80 mg
D. 120 mg

B. 60 mg
240 × (4 / (4 + 12)) = 240 × (4/16) = 240 × 0.25 = 60 mg

A question gives BOTH age and weight. You are told to use Young’s Rule. What do you do with the weight?
A. Use it
B. Ignore it
C. Convert it
D. Average it

B. Ignore it
→ Young’s Rule uses ONLY age

A 10-year-old child needs medication. Adult dose = 500 mg. What is the pediatric dose (Young’s Rule)?
A. 200 mg
B. 227 mg
C. 250 mg
D. 300 mg

B. 227 mg
500 × (10 / (10 + 12)) = 500 × (10/22) ≈ 227 mg

Why are pediatric patients at higher risk of overdose?
A. Smaller organs
B. Immature metabolism
C. Higher sensitivity
D. All of the above

D. All of the above

Which organ immaturity MOST affects drug elimination in children?
A. Heart
B. Liver and kidneys
C. Lungs
D. Skin

B. Liver and kidneys

Why can drugs stay longer in infants?
A. Faster metabolism
B. Immature liver enzymes
C. Increased fat storage
D. Lower absorption

B. Immature liver enzymes

Which drug is avoided in children due to Reye’s syndrome risk?
A. Ibuprofen
B. Acetaminophen
C. Aspirin
D. Amoxicillin

C. Aspirin

Which drug is avoided in children due to respiratory depression risk?
A. Codeine
B. Penicillin
C. Ibuprofen
D. Loratadine

A. Codeine

Tetracyclines are contraindicated in children under 12 because they:
A. Cause liver failure
B. Stain teeth and affect bone
C. Cause seizures
D. Reduce immunity

B. Stain teeth and affect bone

A 7-year-old child. Adult dose = 100 mg. What is the pediatric dose (Young’s Rule)?
A. 32 mg
B. 36 mg
C. 41 mg
D. 50 mg

B. 36 mg
100 × (7 / (7 + 12)) = 100 × (7/19) ≈ 36.8

A child receives 35 mg from an adult dose of 75 mg, based on weight. Which rule was used?
A. Young’s Rule
B. Clark’s Rule
C. mg/kg
D. None

B. Clark’s Rule

Why is mg/kg dosing preferred over Clark’s or Young’s in practice?
A. Easier
B. More accurate
C. Faster
D. Required by law

B. More accurate

What is the MOST important step before calculating pediatric dose?
A. Round first
B. Confirm units
C. Estimate
D. Skip conversions

B. Confirm units

A child weighs 30 kg. Adult dose = 600 mg. What is the Clark’s Rule dose?

30 × 2.2 = 66 lb
600 × (66 / 150) = 600 × 0.44 = 264 mg

A technician forgets to convert kg → lb in Clark’s Rule. Result?

Underdose (major error)

If age increases in Young’s Rule, what happens to dose?

Dose increases (approaches adult dose)

Which is MOST dangerous:
A. Underdose
B. Overdose
C. Both equally
D. Depends

B. Overdose (especially in pediatrics)

A 12-year-old weighs 80 lb. Adult dose = 400 mg. Which rule gives a HIGHER dose?
A. Clark’s
B. Young’s
C. Same
D. Cannot determine

A. Clark’s
→ Weight-based often gives higher dose in larger children

A question includes: age, weight, height, gender. You are told to use Young’s Rule. What matters?

ONLY age

Why is Young’s Rule less accurate than Clark’s?

Does NOT account for weight differences

Which is MOST concerning in pediatrics?
A. Slight underdose
B. Slight overdose
C. Timing delay
D. Missed label

B. Slight overdose

Why do infants have increased drug sensitivity?

Immature organ systems + underdeveloped blood-brain barrier

A child’s weight is given but NOT needed. What should you suspect?

They want Young’s Rule