Pediatric drug dosing

Question 1

why is there no standard dose for most pediatric medications

Answer 1

• children grow and develop quickly esp during early childhood
• development of drug metabolism and clearance pathways begin in the fetus and continue throughout childhood

Question 2

what is rapid growth and development accompanied by changes in

Answer 2

1) absorption
2) distribution
3) metabolism
4) elimination

Question 3

absorption in peds

Answer 3

1) comp of intestinal fluids and permeability of gut change as children grow
2) gastric pH is higher in neonates
3) absorb more through skin (larger SA to V ratio)
* watch diphenhydramine and topical anesthetics

Question 4

distribution in peds

Answer 4

• stores of fat and H20 change
• neonates and infants have higher % extracellular H20
• stores of body fat increase

Question 5

metabolism in peds

Answer 5

• enzyme activity in fetus increases in later stages of pregnancy
• different enzymes mature at diff rates
• mature enzyme levels are reached at 2 yrs of age

Question 6

elimination in peds

Answer 6

• depends on renal and hepatic function
• preterm infants develop renal excretion pathways more slowly
• GFR= adult levels 2 yrs of age

Question 7

how are ped dosing recommendations given

Answer 7

1) mg/kg/day

2) mg/kg/dose

Question 8

starting dose

Answer 8

-different for diff age groups

Question 9

what meds are dosed based on body surface area

Answer 9

-ones with toxic side effects (chemo)

Question 10

what are trusted sources that list dosing recommendations

Answer 10

1) tarascon pharmacopoeia
2) uptodate
3) harriet lane handbook (johns hopkins)

Question 11

how it pt weight often recorded in hospitals

Answer 11

Kg

Question 12

how it pt weight often recorded in private offices

Answer 12

pounds

Question 13

how do you convert from lb to kg

Answer 13

divide by 2.2

Question 14

what is recommended amoxicillin dose for oral tx of otitis media in children

Answer 14

80-90 mg/kg.day divided into 2-3 doses

Question 15

for compliance purposed how many doses per day are recommended

Answer 15

BID (two)

Question 16

what is max dose recommendation for amoxicillin

Answer 16

4 grams/24 hrs

Question 17

how do you calculate doses

Answer 17

1) convert lbs to kg
2) calculate mg/kg/day using dosing recommendations
3) divide into 2 daily doses
4) rounding up is usually fine
5) make sure pt weight is documented
- specify concentration or size of tablet
- write medication in actual mg rather than volume or # of pills

Question 18

how is body surface area expressed

Answer 18

m^2

Question 19

why is BSA dosing used

Answer 19

Using BSA, rather than simply weight) more precisely links dosing to maturity of
body organs and metabolic rate, which are important in the distribution,
metabolism, and excretion of drugs.
ii. BSA dosing is used with drugs with a particular high risk of toxicity (e.g.,
chemotherapeutic agents).

Question 20

in what pts should weight based dosing be used?

Answer 20

• pts <18 who are <40 kg

- if pt >40kg used weight based dosing unless it exceeds the recommended adult dose

Question 21

what is the most common scheme in determining dosage in children

Answer 21

weight based

Question 22

medication dosage in overweight children

Answer 22

• is a challenge because pharmacokinetics may be affected

- if greater than 40 kg use adult dose

Question 23

how can you reduce potential for medication errors

Answer 23

1) write orders clearly
2) be careful with day vs dose (dont put d)
3) make pt weight available for pharmacist
4) never place decimal or zero after whole number
5) always put a 0 infront of decimal
6) write out the word unit
7) order meds in mg not mL (exception=septra or bactrim)
8) don’t put qd- write out once daily or q24hrs
9) dont abreviate drug names
10) for microgram write out word or mcg