Paediatric Prescribing

Question 1

What are the absorption considerations? (4)

Answer 1

• Oral - reduced gastric acid and delayed emptying (most significant in neonatal period)
• IM - avoid as low muscle mass and painful
• Percutaneous - enhanced in infants (less barrier)
  IV - do not assume reliability

Question 2

What are the Distribution considerations? (4)

Answer 2

• Extra cellular fluid volume and total volume higher in neonates
• Body fat lower in neonates
• Reduced protein binding in neonates
• Increased volume distribution

Question 3

What are the metabolism considerations? (5)

Answer 3

• Immature hepatic enzyme systems in neonates
• Oxidation and glucuronidation is decreased
• longer plasma half life and increased plasma concentration
• In older children hepatic function is greater than in adults (may need larger dose/kg to achieve therapeutic effect)
• Relative to body size the liver is much larger than in adults

(glucuronidation = the detoxification process that helps remove unwanted substances from the blood (bilirubin, drugs, toxins)

Question 4

What are the Elimination considerations? (4)

Answer 4

• Renal elimination is reduced in pre-terms
• Adult GFR by 3-6 months
• Full tubular function by 12 months
• Renal excretion is the MOST important factor affecting dosing of children at any age