Pharm 2 - Mechanisms of Drug Action

Question 1

State the 4 types of drug antagonism.

Answer 1

Receptor Blockade
Physiological antagonism
Chemical antagonism
Pharmacokinetic antagonism

Question 2

What is meant by Use Dependency when it comes to receptor blockade?

Answer 2

Ion channel blockers

more active the tissue on which a drug is acting, the more effective the blocker

Question 3

Give an example of Use Dependency.

Answer 3

Nociceptors fire at a much faster rate so drugs acting on these will be faster than normal neurons

Question 4

What is physiological antagonism?

Answer 4

Two drugs act on different receptors on the same tissue and have opposite effects

Question 5

What is chemical antagonism?

Answer 5

Interaction of drugs in solution

Question 6

What is pharmacokinetic antagonism?

Answer 6

when one drug reduces the concentration of another drug at the site of its action

Question 7

Define drug tolerance

Answer 7

Gradual decrease in responsiveness due to repeated administration of a drug

Question 8

What are the 5 mechanisms of drug tolerance?

Answer 8

Loss of receptors
Change in receptors
Pharmacokinetic factors
Physiological adaptation
Exhaustion of mediator stores

Question 9

Explain how loss of receptors causes drug tolerance.

Answer 9

cell takes receptors off via membrane endocytosis

receptor downregulation

Question 10

Explain how change in receptors causes drug tolerance.

Answer 10

Conformational change meaning some of the receptors no longer effective

Question 11

Explain how pharmacokinetic factors cause drug tolerance.

Answer 11

Metabolism of the drug increases when given over a period of time e.g. alcohol

Question 12

Explain how physiological adaptation causes drug tolerance.

Answer 12

homeostasis to reduce the effect of the drug

Question 13

Explain how exhaustion of mediator stores causes drug tolerance.

Answer 13

happens with amphetamines,

gets taken up instead of noradrenaline in vesicles so huge amount of noradrenaline in synapse

if you give again you have a less severe response as you have used up all the noradrenaline in the vesicles

Question 14

What are the 4 receptor familes

Answer 14

Type 1 - ionotropic
Type 2 - G protein coupled
Type 3 - tyrosine kinase linked
Type 4 - intracellular steroid type

Question 15

Describe the structure of Type 1 receptors.

Answer 15

4/5 subunits with transmembrane alpha helices

Question 16

Describe the structure of type 2 receptors.

Answer 16

1 subunit but 7 transmembrane domains

Question 17

Describe the structure of type 3 receptors.

Answer 17

single protein with 1 transmembrane domain

Question 18

Describe the structure of type 4 receptors.

Answer 18

steroid receptors found in the nucleus

Question 19

What is the name given to the DNA binding domain of the steroid receptor complex?

Answer 19

Zinc fingers