Exam 2 Multicompartmental Analysis

Question 1

What are the assumptions associated with the one compartment model?

Answer 1

1. the body acts like a single homogenous compartment and drug rapidly distributed uniformly in it
2. the drug is in rapid equilibrium between the blood and the tissues
3. changes in the plasma concentration of drug will result in proportional changes in tissue drug levels

Question 2

Once compartment alone is sufficient to explain what?

Answer 2

drug disposition

Question 3

What is important about lipophilic compounds such as thiopental?

Answer 3

it is a lipophilic compound so it takes a long time to get distributed in fat → fat has opposite concentration since it increases as time goes on compared to other tissues such as blood or muscle)

Question 4

Why is the one compartment model not sufficient?

Answer 4

one compartment model alone is not sufficient to explain drug disposition → more than one compartments are needed

Question 5

What is unique about a two compartment model graph?

Answer 5

one compartment model graph is a linear downward line while two compartment model graph is bi-exponential and bi-phasic → graph curves then straightens out

Question 6

What are the two phases of the two compartment model?

Answer 6

1. distribution phase

2. elimination phase

Question 7

What is the distribution phase?

Answer 7

elimination also occurs but distribution into the tissue compartment governs the slope

Question 8

What is the elimination phase?

Answer 8

elimination from the central compartment governs the slope (when it is linear)

Question 9

What are the variables used in the two compartment model?

Answer 9

A and alpha is for the distribution phase and B and beta is for the elimination phase

Question 10

What are considered macro-constants?

Answer 10

A, B, alpha, beta

Question 11

What are considered micro-constants?

Answer 11

k12, k21, and k10

Question 12

What is another term for the distribution phase?

Answer 12

the alpha phase

Question 13

What is another term for elimination phase?

Answer 13

terminal phase, beta phase

Question 14

What is the comparison between distribution half life (alpha phase) compared to terminal half life (beta phase)?

Answer 14

terminal half life is always larger than distribution half life

Question 15

What is Vc?

Answer 15

volume of distribution in the central compartment

Question 16

What is Vp?

Answer 16

volume of distribution in the plasma compartment

Question 17

What is Vdb?

Answer 17

volume of distribution in the beta phase (post distribution/terminal phase) which is also called Vd,area

Question 18

What is k12?

Answer 18

drug from compartment one to compartment 2

Question 19

What is k21?

Answer 19

drug from compartment 2 to compartment 1

Question 20

What does the graph for a three compartment model look like?

Answer 20

has three distinct phases (A, B, and C)

Question 21

True/false: “A” is called the distribution phase

Answer 21

true

Question 22

True/false: “B” is called the elimination phase

Answer 22

true

Question 23

True/false: the data shows a drug following one compartment model

Answer 23

false → has two distinct phases

Question 24

True/false: this happens because drug distribution into certain tissues is slow

Answer 24

true