Neonates, Paediatrics and Adolescents Flashcards
Describe the significant factors affecting the pharmacokinetics and pharmacodynamics of drugs in neonates, children and adolescents
Identify where to find information to inform your discussions regarding the safety of taking medicines in children
Recognise the importance of modifying your pharmaceutical care to the appropriate age of the patient at different stages of development and maturity
age categorisation and overlap in what?
premature baby newborn (neonate) 0-27days infant 28days-2years child 2-11 years adolescent 12-16/18
overlap in development- cognitive, physical etc
where do highest % infant deaths occur (age cat)?
neonatal period: 70%
standard drugs prescribed to (homeogenous) adults regardless of what 5 aspects?
height weight renal function liver function body composition
but children= NOT homogenous, each individual
BNFc general guidance for children
Meds only given when necessary and in all cases of potential benefit>risk
carefully discuss treatment options with child and carer, distinguish ADRs and effects of medical disorder
when benefits likely delayed, should be highlighted
why pharmacokinetics different in children? Therefore how to consider factors?
organs, body systems, enzymes that handle drugs develop at diff rates/
all PK factors interact and shouldnt be considered in isolation
PK: affects of absorption of diff formulations(3)
Oral, IM, percutaneous
oral
developmental changes in absorptive surfaces of gut,GI motility, intraluminal pH alter rate and extent
slow GI emptying
first pass metab increased for some drugs in kids
IM
erratic absorption due to reduced muscle mass and variable blood flow to/from injection site
Percutaneous
younger patient = increased as thinner stratum corneum, increased skin hydration
PK: affects of distribution of
a) water soluble drugs
b) protein bound drugs
a) ↑ Vd = ↓ conc of drug
=give ↑ dose per kg than adults e.g. gentamicin
b) ↓ albumin in neonates. ↓ PPB = more free drug.
e. g. morphine, phenytoin, diazepam: have greater unbound concs in plasma
Change in distribution of body water and fat in children
younger = greater total body water as % of weight
PK factors: metabolism
how may presence and activity of hepatic enz pathways vary in neonates and infants?
most phase 1 enz appear after birth but show rapid postnatal maturation
phase 2 enz (eg glucoronidation, sulfation) development less well understood
(metabolism, phase 1 enz)
caffeine used in preterm infant but why not after around 1 months age?
half life of caffeine = 20-36hrs in preterm infant.
1 month = rapid increase in metabolism so caffein no of little clinical use (for apnoea of prematurity)
why increased doses needed of morphine by 27-40 weeks to obtain pain relief?
morphine shows conjugation in neonates as young as 24wks. quadruples by 27-40wks = increased doses
PK factors: excretion.
when do GFR and renal function reach adult values?
GFR and renal func (inc tubular secretion) immature, take up to 6 months.
GFR in neonate = 30-40% of adult
GFR and renal func take longer to develop to adults. what does this mean for drugs excreted by kidneys?
example drug?
drugs excreted by kidneys accumulate
-gentamicin- careful dosing and changes to dosing interval
adjust dose regimens and closely monitor
formulae for dosing in children
and the limitations of it
dose = (childs body surface area/adult body surface area) x adult dose
- only approximate
- unreliable for preterm neonates and infants
3 less specific ways of expressing dosing in children?
age banding
- for low therapeutic index drugs
- e.g. paracetamol, amoxicillin
weight mg/kg
*more precise dosing
BSA mg/m^2
- for narrow therapeutic index drugs
- e.g. chemotherpay, immunosuppression
what to consider when prescribing for obese children
dont excees adult dose!!
mg/kg calculations.
how are doses calculated in emergency?
when?
- tables in reference docs
- Broselow tape: child length–> estimate weight
for Adrenaline, atrophine, glucagon
considerations for oral drug admin in children
- how well tolerable
- flavoured meds
- sugar free- reduce cavities
- remind parents: suspension have undissolved particles-shake before use
IV vs IM route in children.
which is not well tolerated and discouraged?
IM- lack of suitable muscle and unpredicatble absorption
in emergency, which route used if oral not tolerated
rectal e.g. diazepam
inhalational and buccal useful too
how must oral drugs be admin to child? 3 considerations
- dont add to feeds. interactions/ denature/ change
- if dont finish bottle = underdose
- some can be added to milk/juice. consult sites
what are the 2 special routes for admin
- Intraosseous (IO): uses highly vascularised bone marrow for drug and fluid delivery. emergency. centre of bone
- buccal: non-invasive, for appropraitely permeable drugs. e.g. buccal midazolam
what to counsel the parent about -meds for children (4)
- what medicines for
- when to take
- how to take
- common side effects and rare but important side effects to be aware of
