Mechanisms of Drug Action

Question 1

4 types of antagonism?

Answer 1

receptor blockade, physiological antagonism, chemical antagonism, pharmacokinetic antagonism

Question 2

What are the 2 types of receptor blockade

Answer 2

Competitive and irreversible

Question 3

What type of blockers show use-dependency

Answer 3

Ion channel

Question 4

What is physiological antagonism

Answer 4

drugs that interact with different receptors that produce opposite effects can generate physiological antagonism. E.g. histamine and noradrenaline administration to produce opposite responses.

Question 5

What is chemical antagonism

Answer 5

uncommon. Interaction of drugs in solution. Dimercaprol is given to lead poisoning victims. It is a chelating agent that forms complexes of the lead which can then be excreted

Question 6

What is pharmacokinetic antagonism

Answer 6

antagonist produces a reduction in the concentration of the active drug at the site of action. It could reduce the absorption of the drug, increase the excretion of the drug, or increase the metabolism of the drug. E.g. barbiturates

Question 7

What can drug tolerance be caused by (5)

Answer 7

pharmacokinetic factors, loss of receptors, change in receptors, exhaustion of mediator stores and physiological adaptation

Question 8

How does X increase drug tolerance: pharmacokinetic factors

Answer 8

repeated administration of the drug results in higher rate of metabolism of the drug. This happens in barbiturates which can be used to treat epilepsy. Also explains alcohol tolerance

Question 9

How does X increase drug tolerance: Loss of receptors

Answer 9

caused by endocytosis, repeated stimulation of the receptor can mean the cell performs endocytosis to down regulate the receptor. This is caused by a sensitivity to overstimulation. (Understimulated cells can also be upregulated).

Question 10

How does X increase drug tolerance: change in receptors

Answer 10

repeated stimulation can result in the receptor staying put on the cell surface but they undergo a conformational change. This conformational change can lead to the agonist to being unable to bind or the agonist to be able to bind but be unable to produce a conformational change making the receptor unresponsive to the agonist.

Question 11

How does X increase drug tolerance: exhausting mediator stores

Answer 11

Repeated stimulus can mean you run out of the endogenous product, e.g. repeated amphetamine use results in running out of noradrenaline

Question 12

How does X increase drug tolerance: physiological adaptation

Answer 12

homeostatic responses go against the effect of a drug. Can cause drug side effects. These homeostatic responses wane over time.

Question 13

What is a type 1 receptor

Answer 13

Channel linked

Question 14

What is a type 2 receptor

Answer 14

G protein coupled

Question 15

What is a type 3 receptor

Answer 15

Kinase linked receptor

Question 16

what is a type 4 receptor

Answer 16

Intracellular

Question 17

Which type is a G protein coupled

Answer 17

2

Question 18

Which type is a Kinase linked receptor

Answer 18

3

Question 19

Which type is a Intracellular receptor

Answer 19

4

Question 20

Which type is a Channel linked receptor

Answer 20

1

Question 21

What is the order of speed of the different receptors

Answer 21

1, 2, 3, 4

Question 22

What is different about type 4 receptors

Answer 22

They’re intracellular and modulate gene transcription

Question 23

What is different about type 2 receptors

Answer 23

They require a second messenger

Question 24

The 2 domains of kinase linked receptors?

Answer 24

Binding and catalytic

Question 25

Where are the binding domains of ion channel linked, G protein coupled and kinase linked receptors

Answer 25

Extracellular, transmembrane, and extracellular