Lecture 18 : Absorption and Distribution of Drugs

Question 1

What is pharmakokinetics

Answer 1

The study of the change in drug and metabolite concentrations in tissue and body fluids (what does the body do with a drug)

Question 2

Single oral dose concentration time graph

Answer 2

Question 3

What is the therapeutic ratio

Answer 3

Question 4

ADME

Answer 4

Question 5

Bioavailability def

Answer 5

Fraction of unchanged drug that reaches systemic circulation

Decreased by poorer absorption, first pass metabolism.

Eg. IV drug delivery has 100% bioavailability

Question 6

Absorption

Answer 6

Depends on route of administration

Depends on chemical nature of compound (lipophility, higher the better), charge (Uncharged = faster), size (smaller = faster)

Depends on formulation

Depends on blood flow to site of delivery

Question 7

Examples of formulation on absorption

Answer 7

Question 8

Routes of administration

Answer 8

Question 9

Absorption from GI Tract (Enteral absorption)

Answer 9

• Consider how drug reacts with food
• Consider rate of transit in guy
• Orally, consider pH sensitivity, needs to pass through stomach
• First pass metabolism

Question 10

Gut vs IV absorption graph

Answer 10

Question 11

Gut vs Plasma Concentration

Answer 11

Question 12

How does pH affect drug movement across membranes

Answer 12

Differences in pH can determine where drugs accumulate, (usually wherever they are ionised)

Question 13

First Pass Metabolism

Answer 13

First pass metabolism is the breakdown of a drug by the liver or gut wall before it reaches the systemic circulation, reducing its bioavailability. It mainly affects drugs taken orally or rectally

Question 14

Common Distributions of Drugs

Answer 14

Question 15

Volume of Distribution Equation and info

Answer 15

Question 16

Vol of Distribution Examples

Answer 16

Question 17

Drug binding to circulating proteins

Answer 17

Question 18

Examples of drugs bound by albumin

Answer 18