Download pharmacokinetics

Pharmacokinetics:
Pediatrics
Allie Punke ([email protected])
The Basics—True or False
• Pediatric patients generally require higher doses of lipophilic
drugs (like diazepam) due to increased fat content at birth
• The Schwartz equation can be used to estimate creatinine
clearance, but caution should be used for interpreting the
results within the first week of life
• Cystic fibrosis patients typically require lower doses of
aminoglycosides due to production of thick mucus making it
more difficult to eliminate the medication
• Hydroxylation is the most developed phase I reaction in
pediatric patients.
Absorption
Pediatrics
Absorption
• An acid labile drug such as ampicillin is ordered for a neonate.
How do you expect the dosing to differ for a neonate versus
an adult?
• A. An adult will likely require a higher dose due to mature
elimination pathways.
• B. An infant will likely require a higher dose because the drug will
not be absorbed as well.
• C. An adult will likely require a lower dose because of the lower
total body water content in adults.
• D. An infant will likely require a lower dose because the drug will
exhibit a higher bioavailability.
Absorption
• How should phenobarbital, a weak acid, be adjusted for
pediatric patients?
• A. Dosing should be increased because it is not absorbed as well
in pediatric patients
• B. Dosing should be decreased because of increased
bioavailability
• C. Dosing should be increased because pediatric patients are
eliminating it much faster
• D. Dosing should be decreased because pediatric patients are not
able to eliminate it as fast
Absorption
• The pH is more (acidic or alkaline) at birth?
• Patients who are fed Q4 hours each should be expected to
have (constant production of acid or a peak in acid production
when fed)?
• Pediatric patients reach adult gastric output of acid around
what age?
• The ________, the ___________ the gastric emptying time.
• A. Younger, shorter
• B. Older, longer
• C. Younger, longer
Absorption
• Patients fed with formula are expected to experience (shorter
or longer) gastric emptying times than human milk fed
patients.
• Because most drugs are absorbed in the _______, pediatric
patients most likely should not be given _________.
•
•
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A. stomach, immediate release
B. small intestine, enteric coated
C. stomach, sustained release
D. colon, immediate release
Absorption
• What are issues to consider when giving medications by these
routes:
• Topically
• IM
• Rectal
• Intraosseous
Distribution
Pediatrics
Distribution
• Pediatric patients typically require:
•
•
•
•
A. Smaller doses of hydrophilic drugs such as aminoglycosides
B. Smaller doses lipophilic drugs such as aminoglycosides
C. Larger doses of hydrophilic drugs such as diazepam
D. Larger doses of hydrophilic drugs such as aminoglycosides
Distribution
• What are some examples of medications that should be used
with caution due to displacement of endogenous protein
bound substrates (like bilirubin)?
Metabolism
Pediatrics
Metabolism
• Which drug is least likely to be affected in a neonate?
•
•
•
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A. A drug undergoing hydroxylation
B. A drug undergoing glucuronidation
C. A drug undergoing oxidation
D. A drug undergoing hydrolysis
Metabolism
• Drugs may undergo different metabolic pathways in pediatric
patients due to immaturity of some pathways
• How is acetaminophen metabolized in a neonate?
• How is theophylline’s metabolism different in a neonate?
Elimination
Pediatrics
Elimination
• When should the Schwartz equation not be used in pediatric
patients?
• Calculate Creatinine clearance for a full term infant who is 24
weeks old. Length=60cm, SCr=0.3
Summary
• Pediatric patients have increased total body water and
decreased total body fat. Recognize how this can affect drug
dosing (i.e. higher doses for water soluble drugs)
• Recognize the different routes of administration available and
which may or may not be the best
• If given the metabolic pathway of a medication, be able to
determine if it will likely be affected
• Know the Schwartz equation and be able to calculate a CrCl
for pediatric patients
Questions?
Good luck on your exam!