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Foundations 511 > Pharmacology Dynamics > Flashcards

Pharmacology Dynamics Flashcards

1
Q

What is the generic name of tylenol

A

-acetaminophen or paracetamol

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2
Q

What are some examples of cellular responses to receptor activation

A

-there can be changes in the ion content of cells directly or inderectly
-reduce signalling by excitable cells
-promote secretion of hormones
-alter contractile activity
-stimulate synthesis of proteins

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3
Q

How do most drugs work?

A

-most drugs bind to a regulatory proteins
->regulatory proteins are those such as ion channels, receptors, enzymes and transporters

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4
Q

What is meant by the term binding?

A

-it is when a small molecule joins with a protein target to form a complex

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5
Q

Do drugs bind to where an endogenous ligand would bind?

A

-yes

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6
Q

What does the term ligand mean?

A

-term used to refer to any small molecule
->ligand can also be a drug, it just needs to bind to a target

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7
Q

Is cell physiology altered when a drug binds to a protein?Why?

A

-yes
->because the function or behaviour of the regulatory protein is altered

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8
Q

What is the Lock and Key model

A

-only a specific shape fits into the protein and activates it

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9
Q

What is a positive allosteric modulator

A

-it doesn’t bind directly to a receptor the agonist binds to
->binds to another site
-but when an agonist comes along, it enhances the effect of the agonist

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10
Q

What is a negative allosteric modulator

A

-it doesn’t bind directly to a receptor the agonist binds to
->it binds to another site
->but when an agonist comes along, it reduces the effect of the agonist

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11
Q

What is an agonist

A

-a ligand that binds to a receptor protein and active the receptor
->almost all endogenous ligands are agonistd

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12
Q

Are majority of the drugs antagonists?

A

Yes

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13
Q

What is nifedipine

A

-L type Ca2+ channel antagonist

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14
Q

What is Bay-K 8644

A

-binds to the same side as nifedipine but enhances the CA2+ flux following depolirization

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15
Q

What is lidocaine

A

-use dependent blocker of voltage activated sodium channels

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16
Q

How do we predict a size of a response of a tissue to a ligand

A

-the fraction of receptors bound by a ligand
->more of the receptors that are occupied the more effect

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17
Q

What determines the fraction of receptors bound by a ligand

A

-the concentration of the ligand in the proximity of the receptors in interest

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18
Q

What determines the tightness of binding between a ligand and a receptor

A

-the higher the number and quality of complimentary interactions, the more tightly the drug binds
-shape(steric hindrance), lipophilic/hydrophilic incompatibility or charge clashes can reduce binding tightness

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19
Q

What shape can you use to describe the binding of ligands to receptors

A

-a hyperbole shape

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20
Q

What does binding affinity mean for a graph showing the ligand concentration and the number of receptors bound

A

-if the graph is more to the right, then that means it has a less of an affinity for a receptor at the same concentration compared to another ligand or drug

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21
Q

What is meant by the term affinity

A

-we are talking about how tightly a drug binds

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22
Q

What is the numerical value used to define affinity at which 50% of the ligand is bound to the target

A

-it is referred to as Kd

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23
Q

What does a Kd allow for

A

-it allows for a quantitative comparisons to be made between binding of different drugs

24
Q

What is selectivity

A

-a drug shows selectivity for a target when it binds with higher affinity

25
Q

What is the equation for a hyperbola that relates ligand binding to concentration

A

-the Hill-Langmuir equation

-it is b/bmax
->b is concentration fo target proteins bound by ligand
->b max is maximum possible binding(total concentration of target proteins)

26
Q

What is a ligand binding study generate

A

-it generates a binding curve
->Kd is used to look at 50% of the targets that are bound

27
Q

What is a concentration-effect curve

A

-it is an EC50 curve
->concentration of a ligand that gives 50% of maximum effect

28
Q

What is a log dose response curve

A

-an in vivo study generates a log dose response curve
->ED 50 is a dose of ligand that generates 50% of the maximum response

29
Q

What is a Quantal Dose response curve? Give an example

A

-demonstrates response in a group of patients where the effect either does or does not occur
->for example, a loss of consciousness to a general anaesthetic

30
Q

Is a quantal dose response curve normally distributed

A

-no
->that is why you need to use a log axis to normalise it

31
Q

Do vast majority of ligands bind reversibly to proteins?

A

-yes
->so there is an equilibrium set up between bound and unbound proteins existing
->ligand associates(going onto target) and dissociation(coming off the target) from the protein
->only bound drug has an effect on protein behaviour

-the consequences of a drug remains

32
Q

What is the relationship between Kd and association

A

-the lower the Kd, the more tightly it binds
->associates more often and remains bound for a longer time

33
Q

What is the k on

A

-the association rate constant
->it doesn’t change for a particular ligand or drug interacting with a receptor

34
Q

How is association rate calculated

A

-kon x [substrate] x [receptor]

-the association rate decreases because the receptor concentration decreases as the complex forms

35
Q

What does a higher kon value mean

A

-a larger kon value is more likely to bind to a receptor than a drug with a lower kon
-it is like a magnet
-higher kon means more likely association
->more likely associations means faster association rate

36
Q

What is the koff

A

-the dissociation rate constant

37
Q

How is the dissociation rate calculated

A

-koff x [complex between ligand and receptor]

-as the complex falls apart, the rate goes down
->it is an exponential decay curve with a half life

38
Q

What does a high koff mean

A

-the one with the higher k off will remain bound for a shorter time and have a faster dissociation rate
-the one with the lower koff will remain bound for longer and slower dissociation rate

39
Q

Describe the relationship between Kd, koff and kon

A

-high drug binding affinity occurs when you have a small koff and or a large kon

-Kd=koff/kon

40
Q

At equilibrium, are dissociation and association occurring together?

A

-yes
->eventually they will be the same rates

41
Q

What does a very small koff mean for the drug amount in plasma

A

-drugs with a very small koff has a very high binding affinity
->drug concentrations in plasma after dose can be extremely low

42
Q

What does a high koff mean for the association rate

A

-the association rate is slow and it can take a long time to reach equilibrium
-max drug binding may occur long after max drug concentration in plasma is reached
->drug can remain bound to targets long after it has mostly disappeared from the plasma(so the effect of the drug continues)

43
Q

What does a very large kon have for the drug concentration in plasma

A

-have very high binding affinities and and drug concentration in the plasma can be very low after a therapeutic dose

44
Q

What is a drug with a high kon likely to do after disscoiating

A

-drug is more likely to re-associate than to diffuse away in the plasma

45
Q

What does rebinding do for the concentration of drugs in the vicinity of the targets

A

-the localized drug concentration could be ten-fold higher than it is in the plasma as a result

46
Q

Are most irreversible drugs enzyme inhibitors

A

-yes

47
Q

How do irreversible drugs work

A

-often an initial reversible interaction, followed by convalent bonding
->the protein is permanently inactive

48
Q

What are examples of irreversible drugs

A

-aspirin
-omeprazole
-tranylcypromine

49
Q

What is agonist efficacy

A

-effectiveness of an agonist in activating a single receptor

50
Q

What happens to tissue response with an agonist who has increased efficacy

A

-as agonist efficacy is increased, the tissue response becomes greater

51
Q

What is a full agonist

A

-causes the tissue to give the maximum response that it could provide

52
Q

What happens as you increase the efficacy of the agonist

A

-as you increase the efficacy, you need to occupy less receptors to achieve the same tissue response

53
Q

Can partial agonist act as an antagonist

A

-yes
->if an endogenous agonist has too much of an effect on a tissue response, a partial agonist can come in and compete for those receptors
->it can then cause less of a response

-note used as an agonist, a partial one cannon over-stimulate the tissue
-used as antagonist even at a high dose, we cannot over inhibit the tissue

-a partial agonist can lead to increased patient safety

54
Q

What is drug potency

A

-semi-quantitative term
-a comparative term
-refers to the relative dose of a drug to achieve a particular magnitude of a response

55
Q

Do you get potency from a binding curve

A

-no from a dose response curve or a concentration effect curve

56
Q

How is potency of antagonist change with binding affinity

A

-potency of antagonist increases as binding affinity increases

57
Q

How is potency of agonist changing with binding affinity and efficacy

A

-potency of agonist increases with binding affinity and efficacy

Foundations 511 (8 decks)

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