paeds pharmacology Flashcards
why drug data can’t just be extrapolated from adults to children
- pharmacokinetic differences
- altered pharmacodynamic responses
- effects on growth and development not known
- different specific pathologies
define off label medicines
licensed for human use but not for use in children below a certain age such as 16/18 years
define unlicensed medicines
no license for human use in this country
unlicensed/ off-label prescribing
formulation administered via a route not intended
used for an indication not intended
used at a difference dose to recommended
children below stated recommended age
used without a license, including those being used in clinical trials
main reason neonates/ infants are more sensitive to drugs than adults
organ system immaturity
describe physiology of child during early post natal period
- rapid growth
- highly variable alterations in drug metabolism and elimination
- low ADR tolerance
- difficult identifying efficacy and toxicity
describe physiology of infancy
body weight gain and body water composition change rapidly, as does the ratio of bodyweight or surface area to organ size and function
describe physiology of a toddler
- associated with lots of minor illnesses
- problems with compliance
describe physiology young child
- enhanced metabolism and excretion
- clearance can change significantly during a single dose regimen
describe physiology adolescence
- sexual development has major affects on body size and compositon
- psychological changes and peer pressure result in behaviours such as smoking, alcohol, and elicit drug use which can alter drug metabolism
examples of drugs with narrow therapeutic index
- digoxin
- SSRI
- anti epileptics
- cytotoxics
when are adult gastric acid and gastric emptying levels reached?
3 years
when are adult absorption values reached in children
6-8 months
benefits of rectal administration of medications in children
- vomitting
- unwilling to take oral meds
- avoids first pass metabolism
describe newborns extracellular fluid volume compared with an adults
around 45% compared to adults 20-25%. drops to 25% @ 1year
total body water composition compared with adults
75-92% compared with 50-60%
fat content term infants compared with adults
12% term infants
18% adults
fat content 1 year compared with adults
30% 1 year
18% adults
describe plasma protein bonding in neonate and effect
reduced
results in greater unbound or active drug
describe blood-brain barrier in neonates
- not fully developed @ birth
- drugs and other chemicals have relatively easy access to CNS
- infants especially sensitive to drugs that affects CNS function, causing CNS toxicity
describe drug elimination in children
takes longer due to immature hepatic metabolism and renal elimination
describe hepatic metabolism in children
- very slow in neonatal period
- neonates especially sensitive to drugs eliminated by hepatic metabolism
- @ adult rates by 1 year
describe hepatic metabolism in older children
can be greater than in adults, with shorter hand life. this can result in greater doses needed for drugs such as anti-epileptics than in adults
when are adult values for renal excretion achieved in children
3-6 months
what metabolic disturbances increase sensitivity to drugs
- fever
- dehydration
- acidosis
what resource can be used for parents and patients to report suspected side effects
- yellow card — online/ leaflet/ calling them
