Children Paeds Flashcards
(47 cards)
What are the 7 ICH age categories
- Preterm newborn
- New born (0-28 days)
- Infant (28 days -1yr)
- Toddler (1-2yrs)
- Pre school (2-5yrs)
- School age (6-11yrs)
- Adolescents (12-18 years)
What biological membrane is more permeable in neonates
The Blood Brain Barrier
Diazepam will cause more sedation in a baby than an older child
What 5 things affects drug distribution
Rate of absorption
Penetration of biological membranes
Perfusion of organs
Drugs disposition to distribute
Drugs affinity for binding
Two examples of drugs with different disposition to distribute
Theophylline distributes in total body water
Gentamicin distributes in extracellular fluid
Is a water soluble drug going to distribute more in a child or elderly person
Child as they have higher water content than elderly
Is there more or less protein binding in children
Less as there are less protein available for drug binding
What is a consequence of children having less protein available for binding
Increased competition for binding sites leads to displacement of endogenous substances such as bilirubin, this can result in CNS toxicity if bilirubin accumulates in the brain(Kernicterus)
What drugs can cause kernicterus in neonates
Sulfonamides(i.e co-trimoxazole)
And
Ceftriaxone
Aside from competition for protein binding what is another consequence of having less protein
Lower plasma levels of protein-bound drugs are required- -> more drug is unbound and able to act.
i.e phenytoin
Give an example of a protein bound drug that has lower plasma level requirements in neonates
Phenytoin
- 6-12mg/L in neonates
- 10-20mg/L in children and adults
When does phase 1 metabolism reach full capacity
6 months
What is phase 1 metabolism (HORN)
Oxidation
Reduction
N-demethylation (theophylline to caffeine)
Hydrolysis(diazepam, phenobarbitone, phenytoin)
Are both Phase 1 and Phase metabolism immature at birth
Yes
What is phase 2 metabolism
Acetylation
Gluconridation(chloramphenicol –> grey baby syndrome)
Sulphation (paracetamol - different route< 12 yrs)
What do babies get grey baby syndrome with chloramphenicol
Immature phase 2 metabolism so no glucuronidation of chloramphenicol
Why do adults need to take much more paracetamol than a child to overdose
In children the sulphation pathway is the main dominant clearance pathway whereas in adults glucuronidation pathways are mature so more clearance
Are the kidney well functioning at birth
Some nephrons are already functioning at 8 weeks gestation
At 26 weeks, all nephrons are present but decreased size and function
- Nephrons fully form at 36 weeks gestation
Why are older drugs used more in paedatrics
More clinical trials done on older drugs
More evidence in practice
Warfarin use in children
Prepubescent children have lower levels of thrombin and protein C. (clotting factors)
So much smaller doses used
Why are children at higher risk of respiratory depression with opioids
earlier development of opioid receptors in the medulla and pons which are responsible for breathing, than other parts of the brain
Why are opioids poor analgesics in new borns
Immature pain pathways
Altered receptor density or response
What immunosupressive drug requires a much higher dose in infants than teenages to provide the same effect
Ciclosporin
who are Codeine ultra-rapid metabolisers
People with gene differences in expression of CYP2D6 - that metabolism codeine too quickly in active form
what is the implication of codeine ultrarapid metabolisers
As it is a prodrug - More codeine enters breast milk.
Codeine and Dihydrocodeine no longer use in maternity wards OR used in children as it can cause sedation and respiratory depression in babies.
