Lecture 32 - Drugs Acting Through Receptors 2

Question 1

What is potency?

Answer 1

Affinity

Efficacy

Question 2

Do drugs with different potencies reach the same maximum?

Answer 2

Yes

Question 3

What is the difference between a weak agonist and a full agonist?

Answer 3

Different efficacies:
Weak: little response in the cell
Full: full response in the cell

Question 4

What is potency?

Answer 4

The amount of drug required to elicit a certain response

Question 5

Draw a dose-response curve of two drugs with different potencies

Answer 5

:)

Question 6

Will a weak agonist ever reach the maximum?

Answer 6

No

Question 7

Will partial agonists ever reach the maximum?

Answer 7

No

Question 8

What is intrinsic efficacy?

Answer 8

This is the ability of the ligand to elicit a response in the cell

It is a property of the drug

Question 9

What is coupling in pharmacology?

Answer 9

Transduction

This is the relationship between the binding of the ligand to the receptor and the transduction pathway

Question 10

The greater the coupling, …

Answer 10

the greater the intrinsic efficacy of the drug

Question 11

Draw a stimulus-response curve for two drugs of different coupling efficiency

Answer 11

Lecture 31

Slide 8

Question 12

Draw a concentration-response curve:

• one drug
• different numbers of receptors

Answer 12

Lecture 31

Slide 11

Question 13

What is the ‘gold-standard’ B-adrenoceptor agonist?

Answer 13

Isoprenaline

Question 14

What are the features of isoprenaline?

Answer 14

High intrinsic efficacy

Question 15

Compare isoprenaline with prenalterol

Answer 15

Isoprenaline: high intrinsic efficacy
Prenalterol: modest instrinsic efficacy

Question 16

Describe an instance of tissue-dependency of the agonist

Answer 16

Prenalterol

Has much less of a response in the gut than in the atria due to the receptor density

Question 17

Describe an instance of disease-dependence of an agonist’s activity

Answer 17

Prenalterol

TIssue has been desensitised to Prenalterol.
Has much less of a response in failing heart than in healthy heart, due to receptor number

Isoprenaline is also less potent in the failing heart

Question 18

What are the drug-dependent factors of potency?

Answer 18

I/ Affinity

II/ Efficacy

Question 19

What are the tissue-dependent factors of potency?

Answer 19

I/ Number of receptors

II/ Coupling

Question 20

What are the different types of antagonism?

Answer 20

I/ Chemical

II/ Functional
Mechanical

Question 21

Describe an example of chemical antagonism

Answer 21

Protamine binds to heparin, neutralising it

Question 22

What type of molecule is protamine?

Answer 22

A polycation

Question 23

What is competitive antagonism?

Answer 23

This is when a molecule binds to the active site of a receptor, preventing a response

Question 24

What is surmountable antagonism?

Answer 24

The antagonism can be overcome by adding more of the agonist

Concontration dependent antagonism

Question 25

Describe the two sites that the agonist and antagonist act on in competitive antagonism

Answer 25

They act on the same site

Question 26

Draw a concentration-response graph of a drug at a certain concentration when there is an antagonist present, and when there is no antagonist

Answer 26

Slide 28

Question 27

Draw a dose-response curve of a drug when there is and isn’t an antagonist present

Answer 27

Slide 29

Question 28

Is the maximum still reached in competitive antagonism?

Answer 28

Yes - if the concentration of the agonist is high enough

Question 29

What is happening in non-competitive inhibition?

Answer 29

The antagonist is binding to an allosteric site, leading to a change in the shape of the active site

Question 30

What is the reason for the difference between partial and full agonists?

Answer 30

Different functional groups