T2 - One-Comp Open Model

Question 1

What factors do rate and extent of tissue distribution depend on?

Answer 1

1. Blood flow to organs
2. Physiological properties of drug
3. Affinity of tissues for drug (binding)
4. Size of organ (Large = greater distribution)

Question 2

What are the basic assumption of a 1-COM model?

Answer 2

1. The body is single uniform compartment
2. Instantaneous administration of entire does
3. Rapid distribution throughout the body
4. Drug elimination starts immediately upon administration
5. The simplest representation of drug disposition

Question 3

What should we do if drug distribution is rapid enough?

Answer 3

Treat that body as a simple compartment

Question 4

What is considered in a well-stirred model?

Answer 4

There is uniform and instantaneous distribution

Question 5

What is Db?

Answer 5

Administration of a dose into a single compartment

Question 6

What is Vd?

Answer 6

-The apparent volume of distribution found in the single compartment
-Not the actual volume, theoretically to which the drug distributes
- Porportional to dose and concentration in plasma

Question 7

What is C0p?

Answer 7

Plasma concnetraion at time 0

Question 8

How do we calculate C0p?

Answer 8

Question 9

What is k?

Answer 9

• Elimination rate constant
• Proportion of the rate of drug elimination and the amount of drug in the body at any given time
• The rate of drug elimination changes as the amount of drug in the body changes
• The summation of all elimination processes

Question 10

How do we calculate k?

Answer 10

Question 11

What is the importance of calculating k?

Answer 11

-Gives us a constant fractional amount of drug that is eliminated
-Allows us to summarize drug elimination independent of amount of drug in body and independent of time (straight line relationship)

Question 12

What is the 1-COM model used for?

Answer 12

1. Predict concentrations in plasma not tissue
2. Assume that tissue concentrations decline proportionally with plasma concentrations

Question 13

What concentrations in the tissue be the same as plasma?

Answer 13

Tissues have different concentration than other tissues, but changes in tissue concentrations are proportional to plasma concentrations

Question 14

Identify the dependent and independent variable of first order processes?

Answer 14

Rate elimination is dependent on amount of drug at a given time
Elimination rate constant is independent on amount of drug at a given time
Clearance is independent of change in concentration of drug

Question 15

What is half-life?

Answer 15

The time it takes for drug concentration to drop by 50%

Question 16

How do we calculate half-life in first order?

Answer 16

Question 17

What is clearance?

Answer 17

• The volume of plasma fluid cleared of drug per unit time (L/h, mL/min)
• Drug elimination from the body without respect to mechanism of elimination (renal, hepatic)

Question 18

How do we calculate clearance?

Answer 18

Question 19

What are the base equation defining system?

Answer 19

Question 20

How do we calculate Vd?

Answer 20

Question 21

How do we calculate AUC?

Answer 21

Question 22

What is the benefit for K?

Answer 22

Allows us to summarize elimination independent of amount and time

Question 23

What are the pK parameters?

Answer 23

Elimination rate constant
Apparent volume of distribution
Clearance
Half-life
AUC