L4 - principle of drug action 2

Question 1

The affinity of a drug

Answer 1

• the molar concentration of drug required to occupy 50% of the receptors at equilibrium
• it is quantified in terms of KD, the concentration of drug

Question 2

Is the KD value low or high when the drug has a high affinity?

Answer 2

Low

Question 3

Efficacy

Answer 3

the ability of a drug to activate the receptor and produces a biological response - AGONIST

Question 4

What are the two main types of agonist?

Answer 4

1) Full agonist - high efficacy and as a result are very effective at producing a biological response
2) Partial agonist - low efficacy and less effective

Question 5

What does the agonist response depend on?

Answer 5

affinity and efficacy

Question 6

Reversible competitive antagonists

Answer 6

1) used to inhibit the effects of a neurotransmitter or hormone
2) their effects can be overcome by increasing the concentration of the AGONIST - i.e. the blockage is surmountable

Question 7

What shift is made by a reversible competitive antagonist?

Answer 7

A parallel shift towards the right of the AGONIST log concentration vs response curve

Question 8

what shift is made by an irreversible competitive antagonist?

Answer 8

An unparallel shift - i.e. the block is not surmountable

Question 9

Antagonist

Answer 9

inhibits the effects of neurotransmitter or hormone; has affinity but ZERO efficacy

Question 10

What is affinity?

Answer 10

it is a measure of how strongly the drug binds to the receptor