Topic 4 - Agonist Efficacy

Question 1

What is Signal Transduction

Answer 1

What happens downstream after a receptor binds to an agonist

Can be amplified

Question 1

What is a Signalling Cascade

Answer 1

Amplifies the initial signal, 1 binding of an agonist can lead to activation of more factors and cause a larger effect

Question 2

Amplification and Efficacy

Answer 2

A better efficacy will lead to a larger amplification causing a greater effect

Question 3

Tissue Response relation to Receptors (Maximum Response)

Answer 3

Not all receptors need to be bound to achieve the maximum possible level of tissue response

Question 4

How can a high efficacy drug and low efficacy drug achieve a similar response?

Answer 4

The low efficacy will have to bind to more receptors to achieve the same result as the high efficacy drug

(Each receptor gives a smaller response. More receptors need to be bound to achieve a similar result)

Question 5

Full Agonist

Answer 5

An agonist capable of achieving the maximum possible response

(High and Low efficacy drugs can both be full agonist, as long as they can get the max effect)

Question 6

Partial Agonist

Answer 6

Achieves less than the maximum possible response even when all receptors are bound

Question 7

Full/Partial Agonist (Binding Affinity and Efficacy)

Answer 7

Binding affinity does not effect the efficacy, the drug can bind very well and still be a partial agonist

Full Agonist has a higher efficacy than Partial Agonist

Question 8

On a binding response curve what does it mean if a curve is more left?

Answer 8

Higher efficacy, less drug is needed to achieve maximum effect

Question 9

On a binding response curve what does it mean if a curve is more right?

Answer 9

Lower efficacy, drug is a partial agonist if the maximum of the curve decreases

Question 10

Spare Receptors (Full Agonist)

Answer 10

The higher the efficacy of an agonist the more unbound receptors

As it takes less receptors bound to achieve a maximum effect

Question 11

Spare Receptors (Partial Agonist)

Answer 11

No spare receptors

Question 12

Why have spare receptors when the endogenous do not need them to produce the maximum effect

Answer 12

Allow for increased efficacy with a one time cost of producing the receptors

Question 13

Clinical Uses of Partial Agonist (Agonist)

Answer 13

A full agonist may be too powerful

Use a partial agonist instead as it will never reach 100% effect no matter how much you add

Curve will start with an initial stimulus

Question 14

Clinical Uses of Partial Agonist (Antagonist)

Answer 14

Can be used when effects of full agonist effects are too much.

Lots of partial antagonist is needed to outcompete the agonist

Curve starts at maximum and will decrease once partial agonist outcompetes the full agonist