Pediatric drug therapy

Question 1

What are the ADME (pharmacokinetics) of neonates

Answer 1

1. Greater body surface area to body size ratio - less drug needed (topical). Prolonged gastric emptying times = longer absorption
2. Higher H20 levels requires more water soluble drug administration
3. Metabolism is much slower in adults
4. Elimination is slower (decreased GFR in premies)

Question 2

What is Vd with high water soluble drugs

Answer 2

Low vd - Drugs will not leave blood stream because they cannot bind and cross into EC tissues (assuming they are large. If they are small molecules and hydrophilic they will go through slit junctions but not into cells)

Question 3

What is the Vd with high lipid soluble drugs

Answer 3

High vd - drugs will distribute throughout the body and into the EC spaces 0assuming drug is not too large)

Question 4

Name a factor that controls Vd

Answer 4

Plasma proteins. Drugs that are bound to proteins are not free drug and therefore will not diffuse readily throughout the body

Question 5

What happens to Vd with a lot of plasma protein

Answer 5

Vd is low

Question 6

What happens to Vd with little plasma protein (i.e. albumin)

Answer 6

Vd is higher

Question 7

What is the plasma protein level like in neonates

Answer 7

The plasma protein concentration are much lower than adults which means there will be more free drug that is unbound. Because of this, toxic levels may be reached sooner

Question 8

What are the pharmacodynamic changes in neonates

Answer 8

More sensitive to CNS depressant effects of opioids

Question 9

What are the ADME of toddlers (12-36mnths)

Answer 9

1. Gastric acid and emptying like adults
2. Use body weight for dosing, also have a fairly high % of water weight
3. Liver metabolism exceeds adults
4. GFR exceeds adults

Question 10

What are the pharmacodynamic changes in all other ages

Answer 10

Not much, the dynamics pretty much mature shortly after the first few months

Question 11

What are the ADME of Child and adolescents

Answer 11

1. Gastric acid/emptying at adult levels
2. Use body weight for dosing, fat stores are getting closer to adults so you will see more drug bound to protein
3. Liver enzymes are like that of an adult
4. GFR rises throughout adolescence, then declines throughout adulthood

Question 12

Name three drugs that have a much slower absorption rate in neonates than other children/adults

Answer 12

1. Acetaminophen
2. Phenobarbital
3. Phenytoin

Question 13

Name two drugs that have the same absorption rate in neonates and children/adults

Answer 13

1. Diazepam

2. Digoxin

Question 14

Name two drugs that have higher absorption rates in neonates than other children/adults

Answer 14

1. Ampicillin

2. Penicillin

Question 15

What are ways to avoid adverse effects in children

Answer 15

1. Start low

2. Calculate via weight based (mg/kg)

Question 16

How is dose expressed in pediatric patients

Answer 16

mg/kg/day or mg/kg/dose

Question 17

Conversion of lb to kg

Answer 17

1kg=2.2lbs

Question 18

Equation for required dose

Answer 18

Weight in kg * Dosage per kg

Question 19

What are the issues with proportional dosing in children

Answer 19

1. Just using a proportion of an adult dose is inadequate because they have different kinetics
2. Kinetics change significantly in the first year of life

Question 20

What absorption differences are seen in neonates

Answer 20

GI acid is much higher, gastric emptying is much slower

Question 21

What distribution differences are seen in neonates

Answer 21

1. Total BW is much more water (EC) than in adults. Adults body weight is contained mostly IC.
   2.

Question 22

What drugs have really adverse reactions in very young

Answer 22

1. Aspirin
2. Chloramphenicol
3. Tetracycline
4. Any lipid soluble drug (may cause high toxicity levels due to low concentrations of bile acids)
5. Preservatives

Question 23

Issues regarding medication adherence in children

Answer 23

1. Difficulties swallowing pills
2. Parents lack of understanding
3. Lack of communication between provider and pt
4. Health literacy