The effect of age on pharmacokinetics

Question 1

What ages define a neonate, infant and child

Answer 1

Neonate: 0-27 days
Infant: 28 days- 1 year
Child: 1-18 years

Question 2

What is chronological age?

Answer 2

Age from birth to current date

Question 3

What is gestational age?

Answer 3

A measure of the age of a pregnancy which is taken from the beginning of the woman’s last menstrual period

Question 4

What is corrected age?

Answer 4

Premature baby’s chronological age - the number of weeks or months it was born early

Question 5

Why is it important for drugs to be made to treat younger ages?

Answer 5

Because they don’t have full development of all their organs

Question 6

What is the difference in composition of water between neonate and adult?

Answer 6

Neonate: 70-80%
By one year the proportion of body

Adult: 50-60%

Question 7

What is the difference in composition of fat between neonate and adult?

Answer 7

Neonate: 10%
By one year the proportion of body

Adult: 25-30%

Question 8

What is the difference in protein binding between adults and neonates?
How does this affect distribution?

Answer 8

Plasma protein concentrations are lower in neonates and children compared with adults
The increased availability of free drug may alter distribution.
This is dependent on other factors such as the maturation of elimination pathways

Question 9

What enzymes are involved in Phase 1 reactions and what are the levels in adults?

Answer 9

Cytochrome P450
Some are undetectable at birth whilst others are already at 30% of adult levels
Full adult levels are reached at 1-2 years