Pediatric drug dosing Flashcards
Why is there no standard dose for most pediatric medications?
- grow and develop quickly. brings changes in absorption, distribution, metabolism, and elimination
- still developing drug metabolism and clearance pathways
How is drug absorption different in pediatric populations?
Gastric pH might be higher in neonates, so affects oral admin
Neonates, infants, and children absorb more through their skin bc of a larger surface area/volume ratio and a thin stratum corneum. need smaller dose.
How does drug distribution change throughout childhood?
Neonates and infants have higher % of extracellular water
Stores of fat increase as growing
Both alter halflife
How does metabolism change throughout childhood?
Enzyme activity in fetus begins to increase in late pregnancy, but different enzymes mature at different rates.
Mature enzyme levels reached at about 2 years
How does elimination change throughout childhood?
Renal and hepatic function develop as neonate develops - GFR doesn’t reach adult level until ~2 yrs old
Preterm neonates develop renal pathways more slowly
Pediatric dosing recommendations
Given as mg/kg/day or mg/kg/dose
Some (esp toxic) are based on body surface area
What three resources should you keep for looking at pediatric dosage recommendations?
Tarascon pharmacopoeia
UpToDate
Harriet Lane Handbook
Convert weight in lbs to kg
divide weight in lb by 2.2
35 lb/2.2 = 15.91 kg
Convert dose of medicine for 22lb 2 year old needing amoxicillin for otitis media
22lb/2.2 = 10kg
Recommended dose of 90mg so - 10kg x 90mg/kg/day = 900 mg/day
Divide into two daily doses - 450 mg bid
How would you write the rx for the 22lb pt needing amoxicillin?
Amoxicillin (400mg/5 ml)
Dispense: 110 mL
Sig: 440 mg (po) BID x 10 days
Three things to make sure are in the rx
Patients weight
Specify concentration (suspension or solution) or size of tablet/capsule
Write order in actual (mg) instead of volume or # of pills
When would you use body surface area for dosing?
In toxic drugs, such as chemotherapy
More precisely links to maturity of body organs and metabolic rate
Why shouldn’t you exceed the maximum adult or large child dosage recommendation for pediatric patients?
Pharmacokinetics of drug could be affected in obese children - don’t know if volume distribution will increase or decrease. lipophilic meds can be distributed widely but not sure how, not sure how liver metabolizes.
What weight should weight based dosing be used until?
40kg
How to avoid medication errors - there’s 10
Write clearly and concisely
don’t write mg/kg/d - could be dose or day. write it out.
Pt weight needs to be available
No decimals or zeros in whole numbers I.e. 3.0
Put zeros in front of decimals - 0.2
Write out the word unit
Order medications in mg
Don’t write qd when writing orders - use “once daily” or q24hrs
no drug abbreviations
Don’t use ug for micrograms! use mcg or microgram
