Pediatric lecture

Question 1

What are the basic conversions needed for pediatric pharmacy practice?

Answer 1

always in metric system
* 2.2 lbs = 1 kg
* 1 teaspoon = 5 mL
* 1 tablespoon = 15 mL
* 1 inch = 2.54 cm

avg adult is 70 kg

Question 2

Define gestational age (GA)

Answer 2

Time elasped between the first day of the last mestrual period and day of birth.
* full term is 38-40 weeks and 50% survival at 22 weeks

Question 3

Define postnatal age (PNA)

Answer 3

Time elapsed from birth

Question 4

Define postmentrual age (PMA)

Answer 4

Gestational age + postnatal age
* combination use for dosing

Question 5

What is the importance of gestantional age?

Answer 5

Takes into consideration the development time in the womb.
* 1 day old baby can have different development depending on if full term vs. premature gestation

Question 6

Define premature.

Answer 6

< 37 weeks gestation

Question 7

Define term

Answer 7

> or = 37 weeks gestation

Question 8

Define neonate

Answer 8

< 1 month old (28 days)

Question 9

Define infant.

Answer 9

1-12 months old

Question 10

Define child.

Answer 10

1 - 11 years old

Question 11

Define adolescent

Answer 11

12 - 18 years old

Question 12

Dose is primarily based on what?

Answer 12

Weight

Question 13

Explain the pediatric calculation of a drug with a wide therapeutic range

Answer 13

mg/kg
When both age and weight are provided –> weight should be used
* generally okay to round by 5-10% (depending on the drug)
* ex. antibiotic

Question 14

Explain the pediatric calculation of a drug with narrow theraputic range

Answer 14

mg/m^2 - body surface area
* ex. chemotherapy –> should not be rounded

Question 15

Explain how medications beyond neonates are dosed.

Answer 15

Medications beyond neonates are generally dosed per day if scheduled or per dose if given as needed.

Question 16

Explain dosing of neonates.

Answer 16

• use Neofax or neonatal reference
• dose can be based on PNA or a combination of PNA, GA, and PMA depending on the medication
• cannot extrapolate from pediatrics

Question 17

A 25 lb child needs amoxicillin for her ear infection. It should be dosed at 90 mg/kg/day in 2 divided doses. Max adult dose is 2 g/dose.

Answer 17

• 25 lb/2.2 lb = 11.4 kg
• 11.4 kg x 90 mg/kg/day = 1026 mg/day
• 1026 mg/day / 2 doses/day = 513 mg/dose

Question 18

Describe what should be done if older children or adolescents reach the max adult dose?

Answer 18

• Patients will reach the adult max dose around 20-35 kg
• Do not dose mg/kg past the max adult dose!

Question 19

For amoxicillin, generally the max is 1000mg/dose, so for ear infections if given twice a day that would max at 2 grams per day. What weight would this max out at?

Answer 19

• 1000 mg/dose x 2 doses = 2000 mg
• 2000 mg / 90 mg/kg/day = 22.22 kg/day

Question 20

What factors need to be considered for oral absorption in children?

Answer 20

• gastric pH
• intestinal motility
• rate of gastric emptying

Question 21

Describe the gastric pH of neonates.

Answer 21

First few weeks of life –> less acidic (pH >4)
* premature neonates are unable to produce significant acid for first 1-2 weeks.
* pH is similar to adults by 2 years old
* adult pH ~ 0.9-1.5

Question 22

Explain the absorption difference between a weakly acidic and weaky basic drug in neonate.

Answer 22

Weakly acidic drug
Drug is charged in the stomach –> cannot cross the lipid bilayer readily to be absorbed

Weakly basic drug
Drug is neutral in the stomach –> can cross the lipid bilayer readily to increase absorption

In neonate, there less weakly acidic drug absorbed and more weakly basic drug absorbed

Question 23

Describe intestinal motility in pediatrics.

Answer 23

Variable in young infants and neonates
* difficult to predict the rate of absorption and extent of absorption

Question 24

Compare gastric emptying of ped. patients and adults.

Answer 24

At birth and in premature neonates: prolonged gastric emptying
Around 4 months: similar gastric emptying

Question 25

What factors influence gastric emptying time?

Answer 25

• gestational age
• food intake
• disease states

Question 26

Describe absorption through the GI tract of neonate, infant, and children.

Answer 26

Question 27

Describe the non-oral routes of administration.

Answer 27

IV
* optimal bc bioavailability = 1
* requires radiology to find small veins

IM
* painful –> sometimes necessary
* not much muscle mass to work with

transdermal
* not usually intentionally used –> often inadvertent use leading to toxicity
* not fully formed skin increases absorption

rectal
* dosage form issues
* depending on location, may worry about first pass mechanism

Question 28

Describe the water/fat distribution in neonates and young infants.

Answer 28

Neonates and young infants have high total body water and extracellular water.
* babies are bags of water
* older infants have increased lipophilic distribution

fat composition:
12 month old - 23%
15 year old - 13%

Question 29

Identify commonly used water-soluble medications.

Answer 29

In neonatal period meds increase mg/kg dosing vs. in older patients

• caffeine, gentamicin, indomethacin, linezolid, morphine, vancomycin

Question 30

Neonates have increased free fraction of medications that are highly protein bound due to:

Answer 30

• decreased concentration, binding affinity, and binding capacity of plasma proteins
• similar to adults by 12 months old

Question 31

Describe bilirubin.

Answer 31

The byproduct of RBC destruction
* requires conjugation in the liver
* eliminated via the stool
* binds to albumin

Neonates have:
* decreased GI motility
* decreased albumin affinity, concentration, and capacity
* increased permeability of BBB

Question 32

Explain the effect of highly bound protein drugs on bilirubin in the body.

Answer 32

• Bilirubin binds to albumin.
• Drugs that bind highly to albumin can displace bilirubin.
• Bilirubin can penetrate the CNS bc of the unformed BBB –> deposits in the brain and causes brain damage

Question 33

Explain the effect of highly bound protein drugs on bilirubin in the body.

Answer 33

• Bilirubin binds to albumin.
• Drugs that bind highly to albumin can displace bilirubin.
• Bilirubin can penetrate the CNS bc of the unformed BBB –> deposits in the brain and causes brain damage

Question 34

Explain hepatic metabolism in neonates, infants, and preschool aged children.

Answer 34

They have increased relative size of liver –> increased metabolism of some medications.

Question 35

After steady state, ____ provides more information than volume of distribution.

Answer 35

clearance!

Question 36

Explain renal elimination in neonates.

Answer 36

GFR, tubular secretion, and tubular reabsorption are all decreased in neonates.

Question 37

What is considered normal urine output?

Answer 37

Normal for children&raquo_space; 1 mL/kg/hr

Question 38

Explain the modified schwartz equation.

Answer 38

Helpful for pharmacists as MANY medications need dose adjustment for clearance calculations < 50-60 mL/min.
* values > 75 should be reported as such
* most accurate in the range of 15-75 mL/min/1.73m^2

Question 39

Compare the half-life between neonates, children, and adults.

Answer 39

neonates > adults > children
neonates:
* half-life dependent on Vd and clearance

Question 40

What is the KID List used for?

Answer 40

Medications that should be avoided or used in caution in at least some pediatric patients.

Question 41

What are some formulation issues for ped patients?

Answer 41

• alcohol containing liquids
• sucrose content in liquids can worsen diabetic control
• phenylalanine in medications issue in patients with phenylketonuria
• carbohydrate content in meds for patients on ketogenic diet for seizures
• sorbitol contained in medications to prevent intestinal obstruction –> can lead to dehydration and electrolyte imbalance

Question 42

Can sulfamethaxazole/trimethoprim (bactrim) be used in a 7 day old patient?

Answer 42

No. Sulfonamides are not used in patients < 28 days because of bilirubin build up –> brain damage.