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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
What is the equation for a hyperbola that relates ligand binding to concentration
-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
What is a ligand binding study generate
-it generates a binding curve ->Kd is used to look at 50% of the targets that are bound
27
What is a concentration-effect curve
-it is an EC50 curve ->concentration of a ligand that gives 50% of maximum effect
28
What is a log dose response curve
-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
What is a Quantal Dose response curve? Give an example
-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
Is a quantal dose response curve normally distributed
-no ->that is why you need to use a log axis to normalise it
31
Do vast majority of ligands bind reversibly to proteins?
-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
What is the relationship between Kd and association
-the lower the Kd, the more tightly it binds ->associates more often and remains bound for a longer time
33
What is the k on
-the association rate constant ->it doesn't change for a particular ligand or drug interacting with a receptor
34
How is association rate calculated
-kon x [substrate] x [receptor] -the association rate decreases because the receptor concentration decreases as the complex forms
35
What does a higher kon value mean
-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
What is the koff
-the dissociation rate constant
37
How is the dissociation rate calculated
-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
What does a high koff mean
-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
Describe the relationship between Kd, koff and kon
-high drug binding affinity occurs when you have a small koff and or a large kon -Kd=koff/kon
40
At equilibrium, are dissociation and association occurring together?
-yes ->eventually they will be the same rates
41
What does a very small koff mean for the drug amount in plasma
-drugs with a very small koff has a very high binding affinity ->drug concentrations in plasma after dose can be extremely low
42
What does a high koff mean for the association rate
-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
What does a very large kon have for the drug concentration in plasma
-have very high binding affinities and and drug concentration in the plasma can be very low after a therapeutic dose
44
What is a drug with a high kon likely to do after disscoiating
-drug is more likely to re-associate than to diffuse away in the plasma
45
What does rebinding do for the concentration of drugs in the vicinity of the targets
-the localized drug concentration could be ten-fold higher than it is in the plasma as a result
46
Are most irreversible drugs enzyme inhibitors
-yes
47
How do irreversible drugs work
-often an initial reversible interaction, followed by convalent bonding ->the protein is permanently inactive
48
What are examples of irreversible drugs
-aspirin -omeprazole -tranylcypromine
49
What is agonist efficacy
-effectiveness of an agonist in activating a single receptor
50
What happens to tissue response with an agonist who has increased efficacy
-as agonist efficacy is increased, the tissue response becomes greater
51
What is a full agonist
-causes the tissue to give the maximum response that it could provide
52
What happens as you increase the efficacy of the agonist
-as you increase the efficacy, you need to occupy less receptors to achieve the same tissue response
53
Can partial agonist act as an antagonist
-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
What is drug potency
-semi-quantitative term -a comparative term -refers to the relative dose of a drug to achieve a particular magnitude of a response
55
Do you get potency from a binding curve
-no from a dose response curve or a concentration effect curve
56
How is potency of antagonist change with binding affinity
-potency of antagonist increases as binding affinity increases
57
How is potency of agonist changing with binding affinity and efficacy
-potency of agonist increases with binding affinity and efficacy

Foundations 511 (8 decks)

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