Paediatric Pharmacology

Question 1

How is drug absorption different in paediatric patients?

Answer 1

Absorption can be:

• oral: initially reduced gastric acid and delayed gastric emptying. adult levels reached at 3y. Bioavailability of drugs with high hepatic clearance and first pass is reduced and highly variable.
• parenteral: delayed or uncertain delivery
• topically: is enhanced especially with damaged skin
• rectally: used for those vomiting, avoids first pass, significant variation

Question 2

What are the principles of prescribing in children?

Answer 2

Most simple dosage regime
Pay attention to route, formulation and duration of therapy
Always check with the BNFc

Question 3

How do medication pharmacodynamics change with each phase of childhood?

Answer 3

EARLY POST NATAL + INFANCY
Higher incidence of therapeutic errors
Variable metabolism and elimination
Difficult to identify efficacy and toxicity

TODDLER
Usually minor illness; multiple short courses, problems with compliance

CHILD
Enhanced metabolism and excretion, clearance can change significantly

ADOLESCENCE
sexual development & societal change can alter drug metabolism

Question 4

What problems are associated with paediatric prescribing?

Answer 4

Lack of studies in children

Means that medicines used to treat children are off label or unlicensed