Drugs And Receptors

Question 0

Define agonist

Answer 0

Drugs that bind to receptors and cause a response

Have affinity and efficacy

Question 1

Equation for concentration?

Answer 1

Concentration (g/L) = MWt x molarity (M)

Question 2

Define antagonists

Answer 2

Bind to receptors but don’t cause a response

Only have affinity

Question 3

If a drug has a low Kd, what does this mean?

Answer 3

It has a high affinity

Question 4

What does Kd mean?

Answer 4

The concentration required to occupy 50% of receptors.

Question 5

How do we measure Kd?

Answer 5

Binding of a radioactively labelled ligand (radioligand) to cell membranes

Question 6

What is Bmax?

Answer 6

The maximum binding capacity of a receptor

Question 7

What do concentration response curves measure?

Answer 7

Response in cells or tissues

Question 8

What does EC50 show?

Answer 8

The effective concentration giving 50% of a maximum response.

Question 9

What can a response be?

Answer 9

A change in signalling pathway

A change in cell or tissue behaviour

Question 10

What is Emax?

Answer 10

The maximum response

Question 11

What type of drugs are used to treat asthma?

Answer 11

Beta agonists

Question 12

What type of receptors are found in the airways?

Answer 12

Beta 2 and M3

Question 13

Salbutamol:
Kd for β1 = 20mM
Kd for β2 = 1mM
Which one does it have a higher affinity for?

Answer 13

β2

Question 14

What advantage are spare receptors?

Answer 14

Increase sensitivity, allowing responses at low concentrations of agonist

Question 15

What factor does the number of receptors affect?

Answer 15

More receptors increases potency

Question 16

What is a partial agonist?

Answer 16

A drug that cannot produce a maximal response, even with full receptor occupancy.

Question 17

What is a clinical use of a partial agonist?

Answer 17

Morphine is an agonist. Buprenorphine is a partial agonist with a higher affinity but a lower efficacy. Provides adequate pain control with less respiratory depression.

Question 18

What are the types of antagonists?

Answer 18

Reversible competitive antagonism
Irreversible competitive antagonism
Non-competitive antagonism

Question 19

What is IC50?

Answer 19

The concentration of an antagonist that gives 50% inhibition

Question 20

What is irreversible competitive antagonism?

Answer 20

When the antagonist dissociates sloe elf or not at all.

With increased time or [antagonist], more receptors are blocked and non-surmountable

Question 21

When does homologous desensitisation occur?

Answer 21

When the response from a single stimulated receptor population is reduced

Question 22

When does heterologous desensitisation occur?

Answer 22

When response to other agonists become blunted after a single receptor has been continuously stimulated.

Question 23

What is intrinsic efficacy?

Answer 23

A measure of the ability of the drug to activate the receptor