Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PMCOL 200 > Lecture 3 - Pharmacodynamics (Ligands) > Flashcards

Lecture 3 - Pharmacodynamics (Ligands) Flashcards

1
Q

what is a ligand?

A

a substance/drug that binds to a receptor and influences its activity

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

ligands can be ____ or ____ to a receptor

A

agonists or antagonists

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

substances that the body makes which has a physiological effect (typically agonists)

A

endogenous ligand

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

a substance/drug that binds to and activates a receptor to produce a biological response

A

an agonist

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

an agonistic response is usually depicted as a:

A

concentration response curve (or dose-response curve)

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

refers to the concentration of drug that yields a 50% maximal effect

A

EC50 (effective concentration 50)

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

the maximal biological effect observed with the dose response

A

Emax

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

how do you calculate the effect for a given concentration of a drug?

A

E = ((Emax)[drug]) / ([drug] + EC50)

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

the formula used to calculate the effect of a drug is identical to the formula for:

A

the law of mass action

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

what is the implication when [drug] = EC50?

A

a half-maximal effect of the drug is observed (Emax/2)

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

a term that refers to the concentration dependence (Emax)

A

efficacy

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

a term that refers to the concentration dependence (EC50)

A

potency

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

a drug with strong potency has a low:

A

EC50 (only a small concentration is required to generate a large effect)

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

a drug with weak potency has a high:

A

EC50

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

a _____ can generate the maximal observed effect

A

full agonist

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

a _____ can generates a sub maximal effect, regardless of dose

A

partial agonist

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

an _____ causes suppression of basal activity

A

inverse agonist

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

can endogenous ligands be inverse agonists?

A

no

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

true or false: agonists can vary in both efficacy and potency

A

true

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

drugs with different _____ exhibit different concentrations required for a particular effect

A

potency

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

drugs with different _____ exhibit a difference in the maximal effect that can be achieved

A

efficacy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

a type of receptor ligand that blocks a biological response by binding to and blocking receptors rather than activating them

A

antagonist

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

antagonists can be either _____ or _____

A

compoetitive, non-competitive

24
Q

a compound that occupies the same binding site as the agonist, but does not exhibit a biological response

A

competitive antagonist

25
Q

what is a surmountable antagonist?

A

at high enough concentrations, the antagonist is displaced, and maximal efficacy can be achieved

26
Q

what is the “dose ratio” of a schild plot?

A

the ratio of agonist EC50 in the presence vs. absence of antagonist

27
Q

what is the formula for the dose ratio?

A

dose ratio = (agonist EC50 (with agonist)) / (agonist EC50 (no agonist))

28
Q

what is the x-intercept of the schild plot?

A

called the pki and it reflects the potency of the antagonist

29
Q

the highest concentration of antagonist which has no effect on agonist activity

A

pki

30
Q

the higher the pki, the more:

A

potent the drug

31
Q

increasing the concentration of a partial agonist while keeping the full agonist at a constant concentration witll lead to:

A

a reduced response as the concentration of the partial agonist increases

32
Q

like competitive antagonists, partial agonists will lead to a _____ shift in the full agonist _____, but will not affect _____

A

rightward, potency (larger EC50), efficacy (same Emax)

33
Q

what is irreversible competitive antagonism?

A

the antagonist binds irreversibly to the drug binding site and cannot be displaced by increasing agonist concentration

34
Q

what effects does irreversible non-competitive antagonism have on efficacy and potency?

A

reduced agonist efficacy, but no effect on potency

35
Q

activate or inhibit a receptor by binding to a site distinct from the primary (orthosteric) site

A

allosteric ligands

36
Q

what is non-competitive inhibition?

A

antagonist binding at a distinct site from the agonist (an allosteric site) which prevents activation of the receptor

37
Q

drugs that have an allosteric effect that acts to potentiate/enhance the effects of an agonist

A

positive alloseteric modulators?

38
Q

what effects do positive allosteric modulators have on efficacy?

A

increased efficacy or potency, or both

39
Q

alcohol is a positive allosteric modulator at which receptor?

A

the GABAa receptor

40
Q

what is the effect of alcohol on the GABAa receptor?

A

it enhances the effect of the inhibitory neurotransmitter GABA (you need less GABA to bind to the GABAa receptor)

41
Q

drug receptor interaction is determined by:

A

1) binding of the ligand to the receptor
2) generation of a biological response

42
Q

in most cases, ligand binding is reversible, so receptors continuiously switch between:

A

occupied and unoccupied states

43
Q

how well and how long a ligand occupies a receptor is dictated by its:

A

affinity

44
Q

drug affinity is represented by the:

A

equilibrium dissociation constant (Kd)

45
Q

affinity is governed by:

A

electrochemical properties of the receptor and ligand

46
Q

a measure of drug-receptor affinity and efficacy

A

potency

47
Q

a measure of how well a drug activates a receptor

A

drug efficacy

48
Q

unlike potency, efficacy is independent from

A

drug affinity

49
Q

true or false: there is not always a direct relationship between drug effect and drug binding

A

true

50
Q

why can there be this mismatch between drug binding and drug effect?

A

one reason is that there may be more receptors present than are required for activation of a full biological effect

51
Q

having more receptors than is needed to produce a maximal biological effect

A

receptor reserve

52
Q

when receptor reserve is observed, application of small concentrations of an irreversible antagonist does not:

A

reduce the maximum biological effect (need lots of antagonist to reduce the effect)

53
Q

when receptor reserve is observed, it indicates there is a:

A

surplus of receptors

54
Q

true or false: receptor reserve is always observed

A

false

55
Q

receptor binding (affinity) and effect (Emax) are related, but not always:

A

equal

PMCOL 200 (8 decks)

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