Drug target sites Flashcards

1
Q

What do drugs do?

A

Produce specific effects

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

What are the target sites drugs act on?

A

Receptors

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

What are agonists?

A

A drug which acts on a receptor and produces a response (increase/decrease activity of the cell)

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

What is an antagonist?

A

A drug which prevents the response of an agonist

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

What are drug receptor controls?

A

Selectivity of drug effect
Magnitude (size) of response
Mechanisms to mimic/prevent physiological function

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

What is a dose?

A

Amount of drug

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

What is concentration?

A

Amount of drug per unit volume

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

What are the common units of a dose?

A

Micrograms (ug, 10-6 grams)

Nanomoles (nmoles, 10-9 moles)

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

What are the common units of concentration?

A

Micromolar (uM, 10-6 moles per litre)

Nanomolar (nM, 10-9 moles per litre)

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

How does an agonist bind to its receptor?

A

With weak bonds

E.g. electrostatic forces, van der waals bonds and hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the reactions between an agonist and receptor to produce an effect?

A

Agonist + Receptor ←→ Agonist-Receptor
[A] + [R] ←→ [AR]
[AR]→Effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are drug-receptor interactions?

A

‘Stereo-selective’

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

How are ligand/receptor interactions defined?

A

In 3 dimensions

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

What does the ligand/receptor interaction mean?

A

Display selectivity for one stereo-isomer of a ligand over another

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

What is the magnitude of response?

A

[AR] = [A]

[RT] Kd + [A]

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

What does [A] stand for?

A

Agonist concentration

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

What does [AR] stand for?

A

Agonist-receptor concentration

18
Q

What does [Rt] stand for?

A

Total receptor concentration

19
Q

What does Kd stand for?

A

Dissociation sonstant

20
Q

What type of response is the magnitude of response?

A

Hyperbolic

21
Q

What are dose-response curves?

A

Hyperbolic

Complex relationship between dose and response

22
Q

What are log dose-response curves?

A

Sigmoid shape

Simple relationship between log dose and response, i.e. log-linear (between 20% and 80% maximum response)

23
Q

What information can be revealed from a log dose-response curve?

A
Threshold dose
Maximum dose
Effective dose range
Half-maximal effective dose
ED50
24
Q

What is the potency of a log dose-response curve?

A

Related to affinity of drug for receptor
Determines dose required for effect
ED50 is a useful index of potency

25
Q

What is the efficacy of a log dose-response curve?

A

An index of maximum response a drug can induce, i.t. its effectiveness

26
Q

What is the efficacy of full agonists?

A

Have high efficacy (1.0)

Produce the maximum response possible at a given receptor

27
Q

What is the efficacy of partial agonists?

A

Have low efficacy (<1.0)

Fail to produce the maximum response possible at a given receptor

28
Q

How do antagonists block agonists?

A

Act on the same receptor site as the agonist
Act at a different site in the pathway leading to a response
Activate an opposing physiological mechanism
Interact chemically with the agonist

29
Q

What are competitive antagonists?

A

Antagonists which act on the same receptor site as the agonist

30
Q

What do competitive antagonists do?

A

Have affinity for receptor

Compete with agonist molecules for the receptor

31
Q

Why is there no effect when an antagonist binds to a receptor?

A

Antagonist has no efficacy at the receptor

The antagonist/receptor complex cannot activate transduction mechanisms and therefore there is no effect

32
Q

What are the two type of competitive antagonists?

A

Reversible (Surmountable)

Irreversible (Insurmountable)

33
Q

What kind of bonds does a competitive reversible antagonist make with the receptor?

A

Weak bonds

34
Q

What can happen when agonist concentration is increased when a competitive reversible antagonist is attached to the receptor?

A

The chance of agonist molecules interacting with the receptor is increased
The effect of the antagonist can be reversed
The antagonist is competitive and reversible

35
Q

In the presence of a competitive reversible antagonist the agonist log-dose response curve changes how?

A

Is shifted to the right
Is parallel to the curve for the agonist acting alone
Has an unchanged maximum response

36
Q

What happens if the concentration of the agonist increases the reversible competitive antagonist?

A

The agonist overcomes the effect of the antagonist

37
Q

What kind of bonds does a competitive irreversible antagonist create with the receptor?

A

Covalent bonds

38
Q

What happens if an antagonist creates covalent bonds with the receptor?

A

The antagonist binds irreversibly to the receptor
Increasing the concentration of the Agonist cannot reverse the binding of the antagonist
The antagonist is competitive and irreversible

39
Q

In the presence of a competitive irreversible antagonist, what does the log-dose response curve look like?

A

Is not parallel to the log dose-response curve for the agonist acting alone
Has a depressed maximum response

40
Q

What can happen when agonist concentration is increased when a competitive irreversible antagonist is attached to the receptor?

A

Does not overcome the depression of the maximum response produced by a competitive irreversible antagonist

41
Q

What kind of agonist log-dose response curve do some competitive irreversible antagonists produce?

A

Parallel shift before producing a depression in the maximum response