Pediatrics 5 Flashcards
what can chloramphenicol cause
gray baby syndrome
what can cause kernicterus? why?
sulfisoxazole; unable to metabolize bilirubin
common in jaundice babies receiving sulfa drugs
what drug causes “seal babies”
thalidomide
what is a general rule in dose standardization?
standardize doses either as amount per kg or amound per BSA
If dosing of acyclovir for HSV is 60 mg/kg/day; is a 4 kg 5 day old started on 80 mg q8h appropriate?
(step 1 calculate total dose per day = 80 x 3 240 mg/ day)
step 2 total mg/kg/day = 240 mg/day divided by 4 kg = 60 mg/kg/day
id zidovudine is dosed at 180 mg/m2 every 12 hours; what dose would you recommend for a 3 month old who weighs 6 kg and is 55 cm long
- BSA = sqrt (6 kg x 55 cm)/3600 = 0.3 m2
- 0.3 m2 x180 mg/m2 = 54 mg
- formulation of this is 50 mg/ 5ml so 50 mg (1 tsp) every 12 hours in an oral syringe
what should be used for dosing references
pediatric dosage handbook or pediatric lexicomp (not just regular lexicomp)
why are there age specific dosing regimens
“children are not miniature adults” and human growth is not a linear process
how much weight do new borns typically gain per day in the first few months of life
30-40g per day
when should a baby return to there orginal birthweight after they lose some weight initially
7-10 days (about a week)
what are the 4 big pharmacokinetic variables
- Ke
- half life
- volume of distribution
- clearance
what are the 2 independent pharmacokinetic variables
clearance and volume of distribution
what pharmacokinetic variable has to do with dosing interval
clearance
what pharmacokinetic variable has to do with amount per dose
volume of distribution
how is a neonates GI tract different than a normal person
high pH (effecting drugs absorption)
gastric emptying and intestinal motility matures by what age
4 months
how does the ratio of total body weight: BSA compare from a baby to an adult
total body weight: BSA is greater in infants than adults
What lab value is difficult to measure in patients without a large muscle mass (ie babies)
serum creatinine
what pharmacokinetic distribution factors are directly related to gestational age
- bilirubin
- fetal albumin
- acid/base
- glycoproteins
why are aminoglycoside doses so different in babies verse adults
aminoglycosides distribute to ECF and babies have a larger volume of distribution so need a larger dose
why are phenytoin doses so different in babies verse adults
phenytoin is highly protein bound; free concentration is active, so smaller doses in babies do to lower levels of albumin
metabolism can occur where is other than the liver
- blood
- lung
- GI tract
- kidney
at what age is the highest dose of phenobarbital the needed
ages 1-5
why does theophylline work so well in neonates
goes through N-methylation and is broke down into caffeine
instead of N-demethylation that occurs in adults
what are the 3 different types of elimination in the kidneys.
- filtration
- reabsorption
- secretion
how much cardiac output do kidneys ceceive at birth
5-6% (compared to 15-25% in adults)
what is the major way penicillin is eliminated in neonates? why?
eliminated in GFR; tubular secretion does not work well (how it is eliminated in adults)
