Lecture 3

Question 1

What is a graded response?

Answer 1

Usually measured in an individual. The study of a continuum of responses produced from different doses of a drug. Ex: epi

Question 2

What is a quantal response?

Answer 2

Measured in populations. The study of the presence or absence of a response in a population of subjects. Ex: antiseizure med (has seizures or doesn’t)

Question 3

What is the purpose of Dose-Response Studies?

Answer 3

Measure:

1. Potency
2. Intrinsic Activity

Question 4

ED50

Answer 4

Dose of a drug producing 1/2 the maximum effect.

Question 5

ED100

Answer 5

The minimum dose of a drug that produces the maximum effect.

Question 6

Potency

Answer 6

The lower the ED50, the more potent. Inversely proportional.

Question 7

Intrinsic Activity

Answer 7

A measure of intensity of a biological response produced by the ED100 dose, relative to the maximal response that can be produced by the tissue. Ranges from 0-1.0

Question 8

Drugs are classified based upon intrinsic activity.

Answer 8

1. Agonist (high alpha)
2. Partial agonist (alpha = 0.6)
3. Antagonist (alpha = 0)

Question 9

Therapeutic Index

Answer 9

LD50 / ED50;
A measure of drug safety.
Higher is safer.

Question 10

A structurally non-specific interaction

Answer 10

The presence of a drug in a target tissue produces a response. eg mom, mag citrate

Question 11

Structure specific interactions

Answer 11

Structure of drug essential for biological activity. eg: lock and key

Question 12

Sites of binding for structure specific interactions:

Answer 12

1. Membrane components.
2. Cellular organelles.
3. Enzymes

Question 13

Affinity

Answer 13

A measure of the concentration of a drug that saturates 50% of the receptors in a target tissue.
The lower the concentration, the higher the affinity.

Question 14

Efficacy

Answer 14

The ability if an occupied receptor to activate Signal Transduction (ST) to produce a biological response (BR).

Question 15

What is the relationship between potency and affinity?

Answer 15

Typically, the lower the concentration of a drug that binds to its receptor (affinity), the lower the ED50 of that drug (potency)

Question 16

How is efficacy used to classify drugs?

Answer 16

Agonist (high eficacy)
Partial agonist (moderate efficacy)
Antagonist (little efficacy)
This means it depends on the ability of the drug to induce a conformational change in the receptor, that leads to ST and BR.

Question 17

What is the relationship between efficacy and intrinsic activity?

Answer 17

Agonists have the highest intrinsic activity and efficacy.

Antagonists have the lowest intrinsic activity and efficacy.