Introduction to Pharmacology - Lecture 1

Question 1

What does a Endogenous substance mean?

Answer 1

Refers to a substance from within the body

Question 2

What does a Exogenous Substance mean?

Answer 2

Refers to a substance from outside the body

Question 3

What does Pharmacology comprise of?

Answer 3

Pharmacodynamics

Phamcokinetics

Question 4

What is Pharmacodynamics?

Answer 4

This is what a drug does to the body (Biological effects and mechanism of action)

Question 5

What is Pharmacokinetics?

Answer 5

This is what the body does to a drug (Absorption, distribution, Metabolism, Elimination)

Question 6

What is a drug?

Answer 6

Any synthetic or natural substance that is used in the treatment or prevent of disease

Question 7

What must a drug have to be effective as a therapeutic agent?

Answer 7

A degree of selectivity

• Targets a particular biological process

Question 8

How do drugs act?

Answer 8

Act by binding to target molecules

• Lock and Key Hypothesis

Question 9

How is selectivity achieved for drugs?

Answer 9

The Chemical structure of the drug is only recognised by the target receptors

Question 10

What do drugs general bind to, to cause an effect?

Answer 10

Enzymes 
Carrier Molecules 
Ion Channels 
Receptors 
RNA 
DNA

Question 11

What is a receptor?

Answer 11

Receptors are macromolecules that mediate the biological actions of hormones and neurotransmitters

Question 12

Drugs acting on receptors can act in two ways - what are these ways?

Answer 12

As an Agonist

As an Antagonists

Question 13

What is a ligand?

Answer 13

A molecules that binds to another l(usually larger) molecule

Question 14

What is an agonist?

Answer 14

A substance that binds to a receptor to produce a cellular response

Question 15

What is an antagonist?

Answer 15

A substance that blocks the actions of an agonist. `

Question 16

What does an agonist do to the receptor?

Answer 16

Agonist binding causes a conformation change in a receptor

Question 17

What is the equation to define an agonist’s reaction with a receptor?

Answer 17

A + R AR AR* (activated)

Question 18

What is the efficacy of a reaction?

Answer 18

Efficacy is the ability of an agonist to evoke a cellular response

Question 19

What is the affinity of a reaction?

Answer 19

Affinity is the strength of association between a ligand and a receptor
(The longer the agonist stays on the receptor the higher the affinity)

Question 20

What is the term used when the receptors are 100% occupied?

Answer 20

Saturation point

Question 21

What is the relationship between receptor occupancy and agonist concentration?

Answer 21

Hyperbolic

Question 22

What is the Effective Concentration 50?

Answer 22

EC50 is the concentration of agonist that elicits a half maximal response (At which 50% of the receptors are occupied)

Question 23

What is the symbol given for Effective Concentration 50?

Answer 23

EC50

Question 24

What type of graph is often used instead of a hyperbola?

Answer 24

Semi-logarithmic plot (Response % vs Agonist concentration)

EC50 can still be calculated

Question 25

What defines potency?

Answer 25

The EC50 value

Question 26

What will a highly potent drug have in terms of EC50?

Answer 26

It will have a lower EC50

As less of the drug is required to elicit a response

Question 27

What will weak (no potent drug have) for an EC50 value?

Answer 27

It will have a high EC50 value

Question 28

How is Efficacy determined?

Answer 28

The Maximum response

Question 29

Do Antagonists have “affinity”?

Answer 29

Yes - as they elicit a response by binding to them and blocking them, but not activating them

Question 30

Do Antagonists have “Efficacy”?

Answer 30

No

Question 31

What are the two types of antagonism?

Answer 31

Competitive antagonism

Non-competitive antagonism

Question 32

What is competitive antagonism?

Answer 32

COMPETITIVE ANTAGONISM is where binding of agonist and antagonist occur at the same
(orthosteric) site and is thus competitive and mutually exclusive.

[Orthosteric Site is the site where endogenous substance binds]

Question 33

What is non-competitive antagonism?

Answer 33

Where the agonist binds at the orthosteric site and the antagonist binds at the allosteric site. Both may occupy simultaneously.

Activation cannot occur when the antagonist is bound

Question 34

What happens to the Semi-logarithmic plot (Response % vs Agonist concentration) in the presence of a competitive antagonist?

Answer 34

Curve is shifted parallel to the right

Slope remains the same shape

Maximum remains the same

EC50 is increased - The drug becomes less potent

Question 35

What happens to the Semi-logarithmic plot (Response % vs Agonist concentration) in the presence of a Non-competitive antagonist?

Answer 35

Position of the agonist response curve stays the same

Slope is decreased

Maximum response is deceased

EC50 is unchanged (Potency is unchanged)

Efficacy is reduced