Paediatric Pharmacotherapy

Question 1

Pharmacokinetic data

Answer 1

PK data indicates the blood drug levels post drug administration
- obtaining adult PK dta requires repeated blood collection at spaced time intervals.
- blood plasma samples are analysed for drug concentration

Question 2

Gastric emptying rate

Answer 2

• preterm GEMR is slow
• approaches adult rate at 6-8 months

Question 3

Gastric PH

Answer 3

PH is neutral at birth and slowly declines to adult level and by the age of 2 is like an adult

Question 4

Intestinal transit

Answer 4

transit time shorter in young adults
- affects poorly soluble drugs
- immature secretion and activity of bile in neonate
- immaturity of transport systems

Question 5

Body composition

Answer 5

neonates and infants have higher % of extracellular water
- stores of body fat increase throughout childhood
- changes in volume of distribution can alter the drugs half life requiring adjustment of dosing interval

Question 6

Plasma protein

Answer 6

low plasma proteins in neonates and adults

increased free fraction of drug in plasma for highly protein bound drugs

increase vod

protein levels reach adult values in infancy

Question 7

Larger relative size of liver

Answer 7

• increased liver blood flow in infants compared to adults
• increased hepatic clearance
• affects drugs which are extensively metabolised by the liver

Question 8

Liver enzymes

Answer 8

• differences in enzyme expression and activity
• affects hepatic metabolism

Question 9

glomerular filtration rate

Answer 9

• reaches adult value by the first year of life
• affects renal clearance

Question 10

renal tubular transport mechanisms

Answer 10

• affects renal clearance of drugs susceptible to tubular transport

Question 11

Urinary PH

Answer 11

• Infant urinary PH is lower than adult values
• can influence the reabsorption of weak acidic drugs which in turn affect their elimination