Lecture 6

Question 1

Review of Absorption Factors

Answer 1

• Smaller particles cross membranes more easily
• Nonionized particles can cross membranes
• Lipophilic particles can cross membranes

Via passive diffusion

Question 2

Endocytosis + Exocytosis

Answer 2

Other methods of entering and exiting a cell

Question 3

Endocytosis

Answer 3

• Can be leveraged for particle-based drug delivery
• Phagocytosis and micropinocytosis = non-specific
• Calveolar, clathrin-mediated, and receptor-mediated endocytosis are generally selective at varying degrees

Question 4

Is tissue one cell?

Answer 4

No. It is several cells that differ in structure and properties. These different properties can affect drug absorption

Ex: Continuous (skin), fenestrated (kidney), or discontinuous (liver) junctions

Question 5

Diffusion Overview

Answer 5

• Not inhibited
• Equilibrium
• Determined by charge and lipophilicity rather than structure
• Not highly cell-type specific

Question 6

Transporter-Mediated Overview

Answer 6

• Saturable based on number of transporters available
• Can be inhibited
• May be structure specific/selective
• Greater cell type specificity

Question 7

Total absorption =

Answer 7

Sum of all different uptake mechanisms

Question 8

Drug Ionization

Answer 8

• Another major factor in drug update
• Acid absorbed in acid, base absorbed in base
• Ratio of unionized:ionized influences rate of absorption and also distribution and elimination
• Can leads to ion trapping

Question 9

Surface Area

Answer 9

• Also matters in connection with absorption
• Weak acids are readily absorbed in stomach, BUT intestines have a larger surface area than the stomach
• This increase in surface area compensates for the unfavorable unionized:ionized ratio

Question 10

Absorption

Answer 10

Movement of a drug from its site of administration into the bloodstream

Question 11

Tmax

Answer 11

Time to reach Cmax

Question 12

Cmax

Answer 12

The peak plasma concentration of a drug after administration.

Question 13

AUC

Answer 13

The integral of the concentration-time curve (after a single dose or in steady state).

Question 14

Endocytosis

Answer 14

A process by which the plasma membrane folds inward to bring substances into the cell.

Question 15

Exocytosis

Answer 15

A process by which vessicle contents are released from the cell following membrane fusion