Receptors Flashcards

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1
Q

Which opiate receptor has the highest affinity for morphine

A

Mu receptor

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2
Q

What are endorphins and enkephalins

A

Endogenous ligands for opiate receptors

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3
Q

Drug definition

A

A known chemical structure which when administered to a living organism produces a biological effect

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4
Q

Types of drugs

A

Synthetic chemicals, plant chemicals and biopharmaceuticals

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5
Q

What is a biopharmaceutical

A

Something that is made from DNA

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6
Q

Medicine definition

A

A chemical preperation that contains one or more drugs admnistered to produce a therapeutic effect

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7
Q

What other compounds do medicines contain

A

Excipients, stabilizers and solvents

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8
Q

Examples of biopharmaceuticals

A

Proteins (could be endogenous), engineered proteins, antibodies, oligonucleotides, gene therapy and regenerative medicine

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9
Q

What is the first generation of biologics

A

Copies of endogenous proteins produced by recombinant DNA technology

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10
Q

What is the second generation of biologics

A

Engineered proteins to improve antibodies

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11
Q

Benefits of biologics

A

Your body doesn’t accept them but treats them as another human antibody

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12
Q

What can biologics be used for

A

Treating cancer and immune diseases

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13
Q

What does MAB mean at the end of a drug name

A

Monoclonal antibody

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14
Q

What does Humira do

A

Recognises an inflammatory mediator known as TNF alpha

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15
Q

How much does Humira cost

A

14,000 million

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16
Q

What is the basis of the Moderna vaccine to treat COVID

A

Injecting people with mRNA that codes for a protein

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17
Q

What is Pharmacoeconomics

A

Considers the cost benefit of a drug

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18
Q

What kind of proteins do drugs exert their actions on

A

Receptors, enzymes, transporters, ion channels

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19
Q

What macromolecules other than proteins can drugs exert their actions on to

A

Antibiotics and antimicrobials

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20
Q

How are receptors classified

A

Structure, pharmacology, signalling mechanisms

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21
Q

What can increasing the dose of a drug do and why

A

Lead to unwanted side effects because no drug is 100% selective and specific

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22
Q

What can malfunction and loss or receptors lead to

A

Disease

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23
Q

What is an agonist

A

A drug that causes the receptor to switch on and bring about a change within the cell once bound to

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24
Q

What is an inverse agonist

A

When bound to a receptor, they reduce signalling to that receptor

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25
Q

What are antagonists

A

When bound to receptor, they do nothing and blocks the receptor from carrying out its action

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26
Q

What is morphine an agonist for

A

Mu receptor

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27
Q

What are Mu receptors

A

They are g-coupled receptors in the location of the brain that processes pain and reward pathways

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28
Q

What are blockers (drugs) and example

A

They enter the pore of the channel and prevent ions from moving through them. For example, Lidocaine

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29
Q

What are modulators (drugs) and example

A

They modify the way the channel behaves, can open more or less. For example, Valium

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30
Q

What does Lidocaine target

A

sodium channels that send information to the brain when you have a painful incident

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31
Q

What do enzyme inhibitors do and example

A

The normal reaction is inhibited. For example, aspirin

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32
Q

What do enzyme false substrates do

A

The molecule enters into the enzyme to produce something that is inactive/ abnormal metabolite is produced

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33
Q

What do prodrug enzymes do

A

Active drug is produced

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34
Q

Examples of transporter drugs

A

Prozac and digoxin

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35
Q

What does Colchicine do

A

Disrupts the cytoskeleton and inhibits the invasion of immune cells into the inflamed joint

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36
Q

What does Paclitaxel do

A

Targets and prevents the diasembly of microtubules

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37
Q

What does Paclitaxel do

A

Targets and prevents the disassembly of microtubules to stop cell division

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38
Q

Main side effects of opiate

A

Chronic constipation and respiratory issues

39
Q

Why is knowing where the receptor is in the body important

A

Helps us predict drug affects

40
Q

Examples of agonists for the MU-receptor

A

Morphine, heroin, methadone, codeine, fentanyl, beta-endorphins

41
Q

What is a ligand

A

Any molecule that binds to the receptor

42
Q

Examples of antagonists for the MU- receptor and what does it do

A

Naloxone, stops heroin activation

43
Q

What are the 4 types of receptor

A

Ligand- gated ion channels, g- coupled protein receptors, kinase linked receptors, nuclear receptors

44
Q

What is the largest class of receptor

A

G- coupled

45
Q

What is kinase

A

Any protein which has enzymatic activity that adds phosphate to another protein

46
Q

What are the fastest receptors

A

Ligand gated

47
Q

Slowest receptors

A

Nuclear (take a couple of hours

48
Q

What is the basic mechanism for ligand gated ion channels to open

A

Ions flow through aqueous pore which is opened when neurotransmitter/ agonist binds. Flow of ions leads to changes in membrane potential causing action potentials to fire

49
Q

Examples of ligand gated ion channels and the number of transmembrane domains

A

Nicotinic, 4
Glutamate, 3
P2XR, 2

50
Q

What happens when agonist binds to g-coupled receptors

A

They signal the change by activation of a g protein

51
Q

What are the g protein subunits in g coupled receptors

A

Alpha, beta and gamma

52
Q

What is the alpha subunit less attractive to (what happens next)

A

GDP so has a greater affinity to GTP. When GDP comes off GTP comes on

53
Q

What happens to the alpha subunit over time

A

It becomes a nuclear kinase

54
Q

What does activation of kinase receptors lead to

A

Changes in transcription

55
Q

What are cytokine receptors useful for

A

Regulate within the nucleus

56
Q

What is an important feature of nuclear receptors

A

They bind directly to DNA to regulate the transcription of genes

57
Q

What percentage of the mammalian genome is regulated by nuclear receptors

A

1%

58
Q

What is an autoimmune disease

A

Makes an antibody to itself and the target can be a receptor

59
Q

What is Myasthenia Gravis

A

Antibodies to nicotine acetylcholine receptors involving muscle contractions

60
Q

What is Gravis disease

A

Where a thyroid receptor is targeted leading to high metabolic rate, increased skin temperature

61
Q

What can epilepsy be caused by

A

A mutation leading to increased stimulus to a receptor

62
Q

What do mutations in the beta- 2 adreno receptors lead to

A

Means that inhalers don’t work

63
Q

What is affinity

A

A chemical property that defines how likely they are to come together

64
Q

What is the constant for the forward and backward reaction

A

K+1 and K-1

65
Q

What is how good a molecule is at fixing a receptor governed by

A

efficacy

66
Q

What is the number of receptors that are occupied by a drug in one point of time determined by

A

affinity

67
Q

what is KD

A

A constant that defines the affinity of a drug for that receptor

68
Q

What is the forward rate of a reaction defined by

A

The forward rate constant multiplied by the concentration of the agonist and concentration of receptors

69
Q

What is the order of reaction for the forward rate and why

A

Second order because it depends on the concentration of two types of molecules

70
Q

What is the reverse rate of reaction equation

A

k-1[AR]

71
Q

What is the dissociation constant equal to

A

The reverse reaction divided by the forward reaction

72
Q

What is KD a direct measurement of

A

affinity

73
Q

What is occupancy governed by

A

Affinity

74
Q

Equation for occupancy

A

number of receptors occupied/ total number of receptors

75
Q

What does occupancy vary between

A

0 (no drug present) and 1 (all receptors occupied)

76
Q

How do we measure affinity

A

Radioligand binding assay

77
Q

What are the steps for measuring receptor affinity

A

Mix these two together, incubate them and filter the sample so only thing left is the receptors bound radioligand, then analyse the data

78
Q

what are some considerations for measuring receptor affinity

A

Controlling the temperature so proteins aren’t digested
Adding antioxidants in case the molecules released from the cells are oxidisable
Free radical scavenger to stop degradation
Avoiding light

79
Q

What must the radioligand be in measuring receptor affinity

A

Must be biologically active and pure chemically

80
Q

Advantages of using hydrogen in measuring receptor affinity

A

Won’t cause issues to the structure, affinity will be maintained
Powerful radioactive substance
Long half life

81
Q

Disadvantages of using hydrogen in measuring receptor affinity

A

Specialised labs required, labelling is expensive and difficult

82
Q

Advantages of using iodine in measuring receptor affinity

A

Similar size of aromatic amino acids
Chemistry involved is straight forward

83
Q

Disadvantages of using iodine in measuring receptor affinity

A

Easily degradable, more radical change in structure of the molecule

84
Q

How do you separate the bound from the free in measuring receptor affinity

A

Wash away the none bound drug

85
Q

What is non-specific binding

A

The ligand will bind to other things in addition to the receptors e.g. plastic test tube

86
Q

How to stop non-specific binding

A

Setting up two test tubes in parallel, add a known concentration of radioactive drug to one and a huge excess of non-radioactive drug to the other
Non-radioactive drug will outcompete radioactive drug
Subtract non-specific binding from the total to get the specific binding

87
Q

What does affinity give us an indication of

A

What levels, of drug are needed in the body to have a therapeutic effect and a way of identifying and defining the type of receptor

88
Q

What kind of relationship do we get between the concentration and the amount of binding

A

Sigmoidal

89
Q

What happens to the values in a sigmoidal relationship

A

They plateau, shows 100% occupancy

90
Q

What does 100% occupancy mean

A

100% of the receptors in that tissue are occupied by that drug

91
Q

What is the Langmuir equation

A

Bound= bmaxXa/ (Xa + KD)

92
Q

The concentration that occupies 50% of the total number of receptors present gives us a direct measure of what

A

KD

93
Q

What does a low KD show

A

High affinity

94
Q

What can the drug Pirenzepine distinguish

A

Distinguishes between the subtypes of muscarinic receptora