Multicompartmental Analysis

Question 1

What type of compartment model is an IV bolus?

Answer 1

2-compartment PK model

Question 2

What are the qualities of a one compartment model?

Answer 2

The body acts like a single homogenous compartment and drug rapidly distributes uniformly in it.

The drug is in rapid equilibrium between the blood and the tissues.

Changes in the plasma concentration of drug will result in proportional changes in tissue drug level

One (i.e., blood) compartment alone is sufficient to explain drug disposition
- Mono-exponential
- Mono-phasic
- C=Coe^-kt

Question 3

When do we need a multi-compartment model?

Answer 3

One (i.e., blood) compartment alone is not sufficient to explain drug disposition. More than one (i.e., multi) compartments are needed
* C=Ae^-alpha(t) + Be^-beta(t)

Ex. Central <–> Peripheral
- Bi-exponential
- bi-phasic

Question 4

Describe the distribution phase of the multicompartmental model.

Answer 4

Elimination also occurs, but distribution into the tissue compartment governs the slope

Question 5

Describe the elimination phase of the multicompartmental model

Answer 5

Elimination form the central compartment governs the slope.

Question 6

What are the PK parameters for 1-compartmental analysis?

Answer 6

kel
t1/2
Vd

Question 7

What are the PK parameters for the 2-compartmental analysis?

Answer 7

k10, k12, k21
t1/2alpha, t1/2beta

Question 8

What is Vp?

Answer 8

Volume of distribution (peripheral)

Question 9

What is Vdb?

Answer 9

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