Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

DEN 2026 - Pharmacology > Agonists and Antagonists > Flashcards

Agonists and Antagonists Flashcards

(50 cards)

Start Studying
1
Q

What are the 3 main molecular targets for drug action?

A
  1. Proteins
  2. Nucleic acids
  3. Miscellaneous targets e.g. metal ions and GIT contents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a receptor?

A

Protein target with which a naturally occurring chemical mediator binds specifically to initiate a cellular response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two classes of chemical mediators?

A
  1. Cell surface receptors

2. Intracellular receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of cell surface receptors?

A

Act as a receptor for molecules too large or hydrophilic to cross the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the function of intracellular receptors?

A

Act as receptors for molecules which are small enough and hydrophobic so can pass through cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens when a chemical mediator on binding with receptor?

A

Shape change which stabilises the active form of a receptor so enhances interaction with signal transduction mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 2 stages of drug action on receptors?

A
  1. Binding

2. Activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of an agonist?

A

Mimic the action of the chemical mediator, cause a shape change so causes a response in a cell or tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of an antagonist?

A

Bind to the receptor but does not cause a shape change so there is no response in a cell or tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What 5 factors affect the size of a response to a receptor agonist?

A
  1. Concentration of drug molecule
  2. Affinity
  3. Intrinsic efficacy
  4. Natural of signal transduction mechanism
  5. Total numbers of receptors present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What 4 things can influence the concentration of a drug molecule?

A
  1. Dose given
  2. Route of administration
  3. Distribution
  4. Rate of elimination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the affinity of a drug?

A

Tendency of a drug to bind to a receptor (strength of attraction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the intrinsic efficacy of a drug?

A

Ability of a drug to activate a shape change in receptor so cause response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What 2 factors affect the proportion of total receptors available occupied?

A
  1. [Agonist]

2. Affinity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do most agonists bind?

A

Reversibly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Occupancy Equation?

A

[Agonist] / [Agonist] + Ka

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does Ka stand for?

A

It is the drugs equilibrium constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the Ka value of a drug found?

A

It is equal to the concentration of agonist when half the receptors are occupied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does Ka measure?

A

Strength of bonds formed between agonists and receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens if a drug has a high affinity to a receptor?

A

Strong bonds form so small [agonist] sufficient to achieve high occupancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Ka is a theoretical measure. What is the practical measure and how does it work?

Study These Flashcards
A

EC50 which measures drug potency downstream of a receptor

22
Q

What is a full agonist?

Study These Flashcards
A

Drug which causes maximum response in receptors i.e. activates shape change in all receptors

23
Q

What is a partial agonist?

Study These Flashcards
A

Drug which produces a smaller than maximum response even at high concentrations

24
Q

What is the efficacy of a full agonist?

25
What 4 types of coupling can affect the extent of amplification of the initial signal and size of a response?
1. Chemical gating of ion channels 2. Activation of G-proteins 3. Direct activations of enzymes 4. Regulation of gene transcription
26
What are antagonist drugs?
Any drug which reduces the response to another drug
27
What are 5 types of antagonist?
1. Competitive 2. Non-competitive 3. Physiological 4. Pharmacokinetic 5. Chemical
28
What is a competative antagonist?
Drugs which compete with naturally occurring chemical mediators or agonists for a binding site on receptor without initiating a cellular response
29
What is the intrinsic efficacy of competative antagonists?
0
30
What is the competitive antagonist for B1 adrenoreceptor?
Atenolol
31
How does atenolol work?
Competes with agonist for binding site but cannot cause a shape change so the muscle does not contract
32
What is a clinical use of atenolol?
Prevent angina as ability of adrenaline and noradrenaline to increase cardiac work is blunted
33
What are the 2 classifications of competitive antagonists?
1. Reversible | 2. Non-reversible
34
What is the only way to influence reversible antagonists?
Increase concentration of agonists
35
What is the effect of a competitive reversible antagonist on the agonist log concentration response graph?
No reduction in maximum response but a greater concentration is needed to produce maximum response
36
Why do some antagonists bond irreversibly?
They form covalent bonds
37
What is the only way to overcome irreversible antagonists?
Create new receptors
38
What is an example of an irreversible antagonist drug?
Clopidogrel
39
What is the function of clopidogrel?
Anti-platelet drug to inhibit thrombus formation
40
What is the effect of a competitive irreversible antagonist on the agonist log concentration response graph?
Progressive reduction in maximum response to agonist without a shift in concentration
41
What is a non competitive antagonist?
An antagonist which affects action of agonist at some point in the chain leading to a response but does not compete for the same binding receptor as the agonist
42
Give 2 examples of how non competitive antagonists can work
1. Binding to an allosteric site to cause conformational change on agonist receptor 2. Interference with a component of the signal transduction pathway
43
What is a physiological antagonist?
An antagonist with an opposite affect to an agonist but achieves the result by acting on separate cells i.e. two systems are involved
44
What is an example of a physiological antagonist?
Parasympathetic nervous system releasing acetylcholine in nerves supplying heart to counter sympathetic response
45
What is a pharmacokinetic antagonist?
A drug concentration can be decreased if another drug interferes with its ADME
46
What are 2 examples of chemical antagonists?
1. Heparin | 2. Protamine sulphate
47
How are receptors initially divided?
Receptor families
48
How are receptor families divided?
Family members
49
What are receptor families based on?
Which mediators a receptor responds to
50
What 3 things are family members based on?
1. Potency of endogenous mediators at receptors for that mediator in different tissues 2. Selective stimulation by agonist drugs 3. Selective blockade by competitive antagonist drugs

DEN 2026 - Pharmacology (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions