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Y1 - ICPP > Lecture 17 - Pharmacodynamics > Flashcards

Lecture 17 - Pharmacodynamics Flashcards

1
Q

What is a ligand?

A

Chemical/molecule which binds to a receptor

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2
Q

What happens when a ligand binds to a receptor?

A

Causes conformational change
Signal transduction
Response produced

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3
Q

What type of drug is Salbutamol?

A

B2 selective agonist

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4
Q

What does Salbutamol treat?

A

Asthma

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5
Q

What type of drug is Bisoprolol?

A

B1 selective antagonist

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6
Q

What can Bisoprolol treat?

A

Hypertension
Angina

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7
Q

What type of drug is co-codamol?

A

Mu -opioid receptor agonist

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8
Q

What is co-codamol used for?

A

Analgesic

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9
Q

What type of drug is Atorvastatin?

A

HMG-CoA reductase inhibitor

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10
Q

What is Atorvastatin used to treat?

A

Dyslipidemia

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11
Q

What are the units, Molar, Millimolar, micromolar and nanomolar?

A

mM = 10^-3 0.001M
Micromolar = 10^-6 0.0000001
nM = 10^-9

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12
Q

Why is concentration of drug molecules around receptors critical in determining drug action?

A

Low concentration means receptor less likely to be activated

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13
Q

Do most drugs associate permanently or reversible with receptors?

A

Most bind reversibly

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14
Q

What is an agonist?

A

Ligand that binds to the receptor activating it

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15
Q

What is an antagonist?

A

A ligand/drug that blocks a receptor preventing an agonist binding to the receptor

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16
Q

Agonists and antagonists for receptor have an affinity for that receptor.
What is meant by affinity?

A

The liking/attraction for a ligand to bind to a receptor

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17
Q

What is intrinsic efficacy?

A

Ability for a ligand to change a receptors shape to activate it

(R*) = activated receptor

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18
Q

Describe an agonist in terms of affinity and intrinsic efficacy:

A

Has Affinity for the receptor
Has Intrinsic efficacy (so activates receptor)

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19
Q

Describe an antagonist in terms of affinity and intrinsic efficacy:

A

ONLY has Affinity for receptor
NO INTRINSIC EFFICACY (Doesn’t activate receptor)

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20
Q

What is clinical efficacy?

A

How well a treatment succeeds in completing its aim

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21
Q

What is Efficacy?

A

Takes into account intrinsic efficacy and the things that happen that lead to the desired therapeutic response

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22
Q

What is Bmax?

A

Bmax = Maximum Binding Capacity

When all receptors have ligands bound to them

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23
Q

What is Kd?

A

The concentration of the drug which causes 50% occupancy of ligands bound to receptors
(Conc when 50% of receptors have ligands/drugs bound)

The dissociation constant

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24
Q

What does the value of Kd actually indicate?

A

The affinity/strength of interaction of the ligand and the receptor

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25
If a ligand has a high Kd value what does this indicate? If a ligand has a low Kd value what does this indicate?
High Kd = Low affinity (more drug needed to reach 50% occupancy) Low Kd = High affinity (less drug needed to reach 50% occupancy)
26
Why is it useful for drugs to have a high affinity for a receptor? (Low Kd value)
Smaller amounts of drugs can be given
27
What occurs to the respiratory system as a result of a heroin or morphine overdose?
Respiratory depression Then death
28
How does Naloxone treat a heroin overdose?
Antagonist to mu opioid receptor Naloxone outcompetes the opioid
29
What must a drug have in order to cause a response when bound to a receptor?
Efficacy
30
What is Emax?
The maximum response that can be reached
31
What is EC50?
(Effective concentration giving 50% of maximal response) The concentration of drug needed to reach 50% of the maximum response
32
What does the value of EC50 indicate?
Drug potency
33
What is Potency?
The amount of a drug needed to cause a response (Describes response not binding
34
What does potency depend on?
Affinity Intrinsic efficacy Cell/tissue-specific component that allow for the response to happen
35
What is concentration of drug at a drug site?
When the concentration of a drug at a site of action is KNOWN
36
What is dose of a drug at a drug site?
When the concentration of a drug at a site of action is UNKNOWN
37
Give an example of functional antagonism:
When treating asthma give a B2 adrenoceptor agonist This apposes the pathological bronchoconstriction causing smooth muscle to Releaf (bronchodilation)
38
In treating asthma why does the Beta 2 adrenoceptor agonist need to be selective/specific?
Don’t want to stimulate B1 adrenoceptors in the heart (unwanted +ve chronotropy, +ve inotropy)
39
Describe the selectivity of Salbutamol for B2 receptors in terms of affinity and efficacy:
Has high affinity for B2 receptors High selective efficacy for B2 compared to B1 Selectivity is based on its B2 selective efficacy
40
Describe the selectivity of Sameterol for B2 receptors in terms of affinity and efficacy:
High affinity for B2 receptors Selectivity based on affinty not selective efficacy
41
Why can Salmeterol not be administered via IV?
Insoluble
42
What are spare receptors?
When there are receptors that dont additionally contribute to a response (When the response is limited by other factors)
43
What is the relationship between EC50 and Kd in order for there to be spare receptors?
EC50 < Kd Means that the concentration of the ligand in order to produce the max response is less that the concentration needed to occupy all receptors
44
What causes Spare receptors to exist?
Amplification in the signal transduction pathway Response is limited (muscle can only contract so far)
45
What is the benefit of having spare receptors?
Increase sensitivity/potency Meaning lower concentrations of agonist is required for full response
46
What can receptor number influence?
The sensitivity to the agonist Maximal response (may not be enough receptors for the maximum response to actually be reached)
47
What affects the number of receptors on a cell?
Cell type Increases with low activity (Up regulation) Decreases with high activity (Down regulation)
48
Why do people need higher doses of morphine the more they have it?
The mu opioid receptors become internalised the more they are used (Down regulation) Means less morphine can bind
49
What is a full agonist?
An agonist that will produce a maximum effect/response when theres full occupancy
50
What is a partial agonist?
An agonist that is unable to produce a maximum affect even with full occupancy
51
What has a higher potency, a full agonist or partial agonist?
Full agonist
52
What is happening in terms of efficacy for partial agonists?
Insufficient intrinsic efficacy (LOWER THAN FULL AGONISTS) for maximum response to be reached
53
What is meant be the EC50 for a partial agonist?
The concentration of the drug needed to to reach 50% of its response (Not the maximum response)
54
How does a larger response relate to intrinsic activity/efficacy?
Larger response = Greater intrinsic activity/efficacy
55
How can you make a partial agonist become a full agonist?
Increase the number of receptors
56
How can partial agonists act as drugs?
They can act as antagonists by binding to receptors and preventing a full response from occurring (prevent full agonists binding)
57
Heroin is an opioid, what is used to treat a heroin overdose?
Buprenorphine
58
How does buprenorphine treat heroin overdose?
Is a partial agonist Binds to mu opioid receptors giving a little high but preventing maximum response preventing RESPIRATORY DEPRESSION and Death
59
How do antagonists generally work?
Block effects of agonists be preventing them from binding
60
What are the 3 types of antagonism?
Reversible competitive antagonism Irreversible competitive antagonism Non-competitive antagonism (usually Allosteric)
61
What is the principle of reversible competitive antagonism?
Relies on the antagonist out competing the agonist for the binding site They do associate and deassociate
62
What is IC50?
Inhibitory Concentration 50 The concentration of inhibitor which inhibits 50% of the maximal response
63
What factors affect the inhibition from a reversible competitive antagonist?
Antagonists Affinity Concentration of Antagonist Concentration of the agonist
64
What can happen if the concentration of the agonist increases but the competitive reversible antagonist does not?
Agonist can outcompete the antagonist so the inhibitory effects can be over come
65
What happens to the concentration response curve with a reversible competitive antagonist?
Same height shifts to the right (Maximal response can still be achieved it just happens at a higher concentration of agonist
66
What is a drug which treats heroin OD that is a competitive antagonist?
Naloxone
67
What receptors does Naloxone bind to preventing heroin from binding?
Mu opioid receptors
68
What is Irreversiible competitive antagonism?
When the antagonist dissociates very slowly or not at all
69
Can increasing the [agonist] overcome the effect of irreversible competitive antagonism?
No since the receptors all remain blocked
70
How do irreversible competitive antagonists affect the response [agonist] curve?
Initially just shift curve further right Then as [antagonist] increases max response decreases since the spare receptors get inhibited
71
What is Phaeochromocytoma?
Tumour of adrenal chromaffin cellls leading to excesss adrenaline/noradrenaline secretion
71
What is Phaeochromocytoma?
Tumour of adrenal chromaffin cellls leading to excesss adrenaline/noradrenaline secretion
72
What drug can be given to treat Phaeochromocytoma to act on A1-adrenoceptors? What drug can be given to treat Phaeochromocytoma to act on B1-adrenoceptors?
Phenoxybenzamine Bisoprolol
73
What does the excess adrenaline acting on A1 adrenoceptors cause?
Vasoconstriction Hypertension Headache Sweating Panic attacks
74
What type of antagonist is clopidogrel?
Irreversible competitive antagonist
75
What does clopidogrel do?
Reduce platelet activation preventing thrombosis
76
What is non competitive antagonism ?
When a ligand binds to a site on the receptor that is not the active site/orthosteric site This reduces the orthosteric ligands affinity for the active/orthosteric site
77
What is the site called which a non competitive inhibitor will bind to?
Allosteric site
78
How can Maraviroc be used with HIV treatment?
Binds to receptors Allosteric site Conformational change of receptor prevents viral ability to bind to receptor Prevents virus entry into cell

Y1 - ICPP (23 decks)

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