Mod IV: Pediatric Pharmacokinetics

Question 1

_{Review of Terms}

The discipline that describes the absorption, distribution, metabolism, and elimination of drugs is also known as:

Answer 1

pharmacoKINETICS

Understood as “the effects of the body on drugs”

Question 2

_{Review of Terms}

The discipline that describes the “the effects of drugs on the body” is also known as:

Answer 2

pharmacoDYMANICS

This is also understood as the intended use of the drug

Question 3

_{Review of Terms}

The extent and rate of uptake of an active drug into the body is also known as:

Answer 3

Bioavailability

Question 4

_{Review of Terms}

What would the bioavailability of an oral drug that has poor absorption or high first-pass metabolism be?

Answer 4

LOW bioavailability

Question 5

_{Review of Terms}

Liver metabolism after oral drug administration is known as:

Answer 5

First-Pass metabolism

Question 6

_{Review of Terms}

What’s a consequence of a HIGH first-pass effect?

Answer 6

Low bioavailability

Question 7

_{Review of Terms}

Which route of administration can bypass the liver and increase the drug bioavailability?

Answer 7

Rectal or sublingual administration

Question 8

_{Review of Terms}

The volume in which the amount of drug would need to be uniformly distributed to produce the observed blood concentration is also known as:

Answer 8

Volume of Distribution (Vd)

This is a theoretical term to quantify the distribution of a drug

[Vd x Drug concentration in blood = total amt of drug in the body]

Question 9

_{Review of Terms}

How can the “Total amt of drug in the body” be calculated?

Answer 9

Total amt of drug in the body

= Vd x Drug concentration in blood

Question 10

_{Pharmacokinetics}

What will determine the absorption characteristics and hence bioavailability of many drugs administered orally?

Answer 10

pH and volume of gastric acid

Question 11

_{Pharmacokinetics}

Which GI factors make the absorption of many drugs variable in the neonate?

Answer 11

Decreased gastric acid secretion

Delayed gastric emptying

Reduced gut motility

Question 12

_{Pharmacokinetics}

Some of the first pass metabolism of the liver may be bypassed by rectal administration. How is absorption in children via this route?

Answer 12

Variable

Question 13

_{Pharmacokinetics}

Some of the first pass metabolism of the liver may be bypassed by rectal administration. Absorption in children via this route is variable. What’s the lag time to detectable blood levels after rectal administration?

Answer 13

40 minutes

Question 14

_{Pharmacokinetics}

How is the bioavailability of drug adminstered IM?

Answer 14

High bioavailability

Question 15

_{Pharmacokinetics}

Why is the IM route usually avoided unless child is asleep

Answer 15

Painful!!!

Question 16

_{Pharmacokinetics}

What’s the Total body water content the Premature neonate?

Answer 16

85-90% of body weight

Question 17

_{Pharmacokinetics}

What’s the Total body water content for a Term neonate/infant?

Answer 17

70-75% of body weight

Question 18

_{Pharmacokinetics}

At what age does the Total body water content decreases to adult levels of 50-60%?

Answer 18

by 1-year of age

Question 19

_{Pharmacokinetics}

What percentage of Total body water content is ECF

Answer 19

ECF = 40% of total body water

Question 20

_{Pharmacokinetics}

T/F: ECF decreases in parallel with TBW

Answer 20

True

Question 21

_{Pharmacokinetics}

A what age does ECF reaches adult levels of 20% of TBW?

Answer 21

by 1-year of age

Question 22

_{Pharmacokinetics}

Why is the optimal dose (per kilogram) of most IV anesthetics disproportionately greater in neonates, infants, and young children?

Answer 22

VD for most IV anesthetics is disproportionately greater in neonates, infants, and young children

Question 23

_{Pharmacokinetics}

Why is there impaired metabolic hepatic function in neonates?

Answer 23

Immature biotransformation pathways & hepatic enzyme systems

There is also Decreased hepatic blood flow

And ½ life is markedly prolonged

Question 24

_{Pharmacokinetics}

There is More rapid clearance in infants & children. Why?

Answer 24

Increased hepatic blood flow

Liver receives higher fraction of C.O

½ life usually shorter than adult

Question 25

_{Pharmacokinetics}

With drug Excretion, there is Decreased GFR. Why?

Answer 25

Immature renal tubular function

Impaired renal drug handling, hepatic metabolism or biliary excretion of drugs

Question 26

_{Pharmacokinetics}

What’s the GFR at 1 day?

Answer 26

15%

Question 27

_{Pharmacokinetics}

What’s the GFR at 1 week?

Answer 27

25%

Question 28

_{Pharmacokinetics}

What’s the GFR at 3 months?

Answer 28

50%

Question 29

_{Pharmacokinetics}

What’s the GFR at 6 months?

Answer 29

60%

Question 30

_{Pharmacokinetics}

What’s the GFR at 1 year?

Answer 30

80%

Question 31

_{Pharmacokinetics}

What’s the GFR at 2 year?

Answer 31

100%

Question 32

_{Key Points}

Drug dosage calculation typically based on a

Answer 32

per kg

Recommendation

Question 33

_{Key Points}

Estimating body weight (kg) based on age: > 1yr =?

Answer 33

> 1yr = (Age X 2) + 10 kg

Question 34

_{Key Points}

Estimating body weight (kg) based on age: <1yr =?

Answer 34

<1yr = ½ age (mos.) + 4 kg

Question 35

_{Key Points}

Take Home Message = Titrate To Effect. Why?

Answer 35

Response to anesthetic drugs is quite variable between that of neonates, infants, children, and adults