Intro to drug action

Question 1

describe a receptor

Answer 1

• Receptors are proteins that allow a chemical agent (drugs, hormones, neurotransmitters) to initiate a change in cell function
• The cell’s ‘sensing elements’
• Provide molecular communication between
  chemical agent and transduction process

Question 2

Describe the relationship between agonist concentration and receptor
occupancy

Answer 2

there is a positive relationship

the higher the concentration of agonist the more receptor will be occupied

Question 3

Describe the relationship between agonist concentration and response

Answer 3

there is a positive relationship

The more agonist concentration there is the more binding occurs producing an increased response (decreased?)

Question 4

agonist

Answer 4

mimics the actions of endogenous ligands by binding to the receptors

Question 5

explain drug selectivity

Answer 5

each drug only binds to a certain receptor and only certain receptors recognise certain drugs

Question 6

explain antagonism in terms of drug
affinity and efficacy

Answer 6

Bind to receptor but do not produce a change in function
- affinity
- no efficacy

Question 7

explain partial agonism in terms of drug affinity and efficacy

Answer 7

produce submaximal response
- low affinity
- low efficacy

Question 8

Explain the differences between surmountable and insurmountable
receptor antagonism

Answer 8

Surmountable:
- bind reversibly
- agonist concentration response shift to the right however ho change in slope or maximum response

Insurmountable:
- bind irreversibly
- agonist concentration response shifts to the right, reduces maximum response and slope

Question 9

Agonist potency

Answer 9

Concentration required to produce 50% of maximal agonist response (EC50)

The lower the EC50, the more potent the agonist

Potency depends on affinity and efficacy and tissue-dependent parameters