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Pharmacy > Health and Disease Week 6 > Flashcards

Health and Disease Week 6 Flashcards

1
Q

define pharmacology

A

the science of drugs and how they act in biological system

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2
Q

What are the 4 main protein targets for drug action?

A
  1. receptors
  2. ion channels
  3. enzymes
  4. transporters
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3
Q

What do ion channels do?

A

they are present on cellular membranes and open in response to environmental cues, which allows the passage of channel-specific ions down a concentration gradient

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4
Q

What are the 2 ways in which drugs can affect ion channels?

A

blockers and modulators

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5
Q

What do blockers do to ion channels?

A

they block ion channels and prevent ion movement

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6
Q

What do modulators do to ion channels?

A

they don’t block the channel, but bind and increase or decrease the chance of the channel opening

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7
Q

What are the 3 ways in which drugs affect enzyme activity?

A

inhibitors, false substrates, prodrugs

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8
Q

How do inhibitors affect enzyme activity?

A

they block substrate from binding

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9
Q

How do false substrates affect enzyme activity?

A

the enzymes produce an abnormal metabolite

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10
Q

How do prodrugs affect enzyme activity?

A

drugs given to the patient are inactive, so enzymes convert them into active state

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11
Q

What do transporters do?

A

transport substances across membranes, can be against a concentration gradient- but only ONE side of membrane is open at once

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12
Q

What are the 2 ways in which drugs affect transporters?

A

inhibitors and false substrates

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13
Q

How do inhibitors affect transporters?

A

they block activity of the transporter, so it can’t transport substances across the membrane

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14
Q

How do false substrates affect transporters?

A

an abnormal compound will accumulate at the other side of the membrane

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15
Q

What are receptors?

A

proteins that typically sit on cell membrane and respond to exogenous cues and relay a signal into a cell to produce a response

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16
Q

What are the 3 ways in which a drug affects a receptor?

A

agonist, antagonist, modulator

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17
Q

How do agonists affect receptors?

A

activates the receptor when it binds

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18
Q

How do antagonists affect receptors?

A

bind to receptor, but produce NO response, and block activity of the receptor by endogenous activators

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19
Q

How do modulators affect receptors?

A

they bind to elsewhere on the receptor and increase or decrease the ability of the receptor to activate

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20
Q

define receptor

A

proteins, usually on the surface of a cell which receive and transduce signals

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21
Q

define ligand

A

something that binds, can be an agonist or antagonist

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22
Q

define agonist

A

something that binds and produces a response

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23
Q

define antagonist

A

something that binds and produces NO response

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24
Q

define second messenger

A

a molecule that relays a signal from a receptor to an effector

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25
Q

define signal transduction

A

a sequence of second messengers that elicit a biological response

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26
Q

How do receptors work?

A
  1. ligand binds to receptor
  2. causes a conformational change of the receptor protein
  3. results in a cellular effect
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27
Q

What are examples of cellular effects after a receptor is activated?

A

opening of a channel, activation of a linked enzymes. recruitment of an effector protein, intracellular transport

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28
Q

What are the 4 main families of receptor?

A
  1. ligand-gated ion channels
  2. G protein-coupled receptors
  3. Kinase-linked receptors
  4. nuclear receptors
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29
Q

How do ligand gated ion channels work?

A

when a ligand binds, it opens the channel, allowing the movement of channel-specific ions

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30
Q

What is an example of a ligand gated ion channel?

A

acetylcholine and nicotonic receptors

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31
Q

How do acetylcholine and nicotonic receptors work?

A
  1. an electrical impulse travels down the pre-synaptic neurone
  2. this triggers the release of acetylcholine
  3. acetylcholine acts on nicotinic acetylcholine receptors on the post-synaptic neurone
  4. this opens the channel, and allows sodium ion entry, which triggers an impulse in the next neurone
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32
Q

What is kinase?

A

a second messenger and an enzyme

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33
Q

What does kinase do?

A

it uses ATP to phosphorylate targets, and acts as a switch to turn target on or off and allows other 2nd messengers to bind to phosphorylated target protein

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34
Q

How do kinase-linked receptors work?

A
  1. the receptors is on the cell membrane as two halves
  2. when ligand binds to receptors it brings the two receptors halves into a dimer
  3. activates kinase activity of the receptors and a cascade and biological response
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35
Q

What is an example of a kinase-linked receptor?

A

epidermal growth factor receptor

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36
Q

How is epidermal growth factor receptor (EGFR) related to lung cancer?

A

EGFR can promote cell growth, and some patients with lung cancer may express many more EGFR receptors, so experience more growth

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37
Q

What is a G protein-coupled receptor?

A

a receptor with 7 transmembrane domains coupled to a G protein

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38
Q

How do G protein-coupled receptors work?

A

ligand binding activates the G protein bound on the intracellular surface, which interacts with an affector

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39
Q

How are G protein-coupled receptors activated?

A
  1. receptor is in resting state attached to G protein
  2. ligand binds and G protein is activated
  3. GDP is exchange for GTP by G protein
  4. GTP bound G protein interacts with the target effector, which causes a response
  5. the G protein then hydrolyses GTP to GDP and the G protein can dissociate from the effector
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40
Q

What is an example of a G protein-coupled receptor?

A

muscarinic receptors and smooth muscle contraction

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41
Q

How do muscarinic receptors work?

A
  1. muscarinic M3 G-protein coupled receptors are on intestinal smooth muscle
  2. acetylcholine activates M3 receptors
  3. the G protein is then able to bind to effector
  4. contraction of smooth muscle occurs
  5. therefore, antimuscarinics can be used to treat IBS
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42
Q

How do nuclear receptors work?

A
  1. the receptor is NOT associated with the cell membrane, but in the cyotplasm
  2. ligand enters the cell and binds to receptor in the cytoplasm
  3. ligand-receptor pair allows it to change conformation and it can move into nucleus
  4. it then binds to DNA and acts on gene expression
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43
Q

What is an example of a nuclear receptor?

A

oestrogen receptor

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44
Q

How are oestrogen receptors associated with breast cancer?

A

some patients with breast cancer may have more oestrogen receptors, so there is more growth
these receptors can be targeted by Tamoxifen

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45
Q

define pharmacology

A

the science of drugs and how they act in biological systems

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46
Q

What are the 4 main protein targets for drugs?

A
  1. receptors
  2. ion channels
  3. enzymes
  4. transporters
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47
Q

Which 2 ways do drugs affect ion channels?

A

blockers, modulators

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48
Q

How do blockers affect ion channels?

A

they block ion channels and prevent ion movement, paticularly VGNC

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49
Q

How do modulators affect ion channels?

A

they don’t block but they regulate how easily the channel opens or closes, and may need a lower or higher voltage -> so increase or decrease the chance of the channel opening

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50
Q

Which 3 ways do drugs affect enzymes?

A
  1. inhibitors
  2. false substrates
  3. prodrugs
51
Q

How do inhibitors affect enzyme activity?

A

they block activity by binding to active site

52
Q

How do false substrates affect enzymes?

A

they bind to the enzyme and produce an abnormal metabolite

53
Q

How do prodrugs affect enzymes?

A

they are drugs in an inactive state and bind to enzymes to be activated

54
Q

Which two ways do drugs affect transporters?

A

inhibitors and false substrates

55
Q

How do inhibitors affect transporters?

A

blocks activity of the transporter so it can’t move substances across the membrane

56
Q

How do false substrates affect transporters?

A

transporter thinks it is a different substrate, so an abnormal compound accumulates

57
Q

What are the 3 ways in which drugs can affect a receptor?

A

agonist, antagonist, modulator

58
Q

How do agonists affect receptors?

A

they bind to and activate the receptor

59
Q

How do antagonists affect receptors?

A

they bind to the receptor and block activity by other activators -> do NOT activate it though

60
Q

How do modulators affect receptors?

A

they bind elsewhere on the receptor and increase or decrease the ability of the receptor to activate

61
Q

define receptor

A

proteins, usually on the surface of a cell which receive and transduce signals

62
Q

define ligand

A

something that binds

63
Q

define agonist

A

something that binds and induces a response

64
Q

define antagonist

A

something that binds and produces NO response

65
Q

define second messenger

A

a relay signal from a receptor to effector

66
Q

define signal transduction

A

a sequence of second messengers that elicit a biological response

67
Q

What are the steps of a basic ligand-receptor interaction?

A
  1. ligand binds to receptor
  2. this causes a conformational change of the receptor protein
  3. this results in a cellular effect e.g. opening of a channel
68
Q

What are the 4 main types of receptor?

A
  1. ligand-gated ion channels
  2. G protein-coupled receptors
  3. kinase-linked receptors
  4. nuclear receptors
69
Q

How do ligand-gated ion channels work?

A

substance binds to it and opens the channel, allowing movement of channel-specific ions

70
Q

What is an example of a ligand-gated ion channel?

A

acetylcholine and nicotinic receptors

71
Q

What is the function of kinase?

A

an enzyme and second messenger that uses ATP to add a phosphate to targets, activating them

72
Q

How do kinase-linked receptors work?

A

the receptor is on the cell membrane as two halves and binding bring them together, which activates kinase activity and causes a cascade

73
Q

What is an example of a kinase-linked receptor?

A

epidermal growth factor receptor and lung cancer -> EGFR promotes cell growth, so patients with more of these proteins experience mroe growth

74
Q

How do G protein-coupled receptors work?

A

they are receptors with 7 transmembrane domains coupled to a g protein and ligand binding activates the G protein which interacts with an effector

75
Q

What is an example of G protein-coupled receptors?

A

muscarinic receptors and smooth muscle contraction

76
Q

How do nuclear receptors work?

A

the receptor is NOT on the cell membrane, but in the cytoplasm -> ligand-receptor pair allows it to change conformation and it can move into nucleus where it binds to DNA and acts on gene expression

77
Q

What is an example of nuclear receptors?

A

oestrogen receptor and breast cancer

78
Q

Which 2 factors determine a receptor response?

A

affinity and efficacy

79
Q

define affinity

A

how well a drug binds to a receptor

80
Q

define efficacy

A

how well a drug activates a receptor

81
Q

How are receptor responses measured?

A

concentration-response curves

82
Q

How are concentration-response curves plotted?

A

a chosen response is recorded e.g muscle contraction and the recorded response is plotted against LOG agonist concentration

83
Q

describe and explain the concentration-response curve

A
  1. initial low concentration gives limited response as low receptor binding
  2. more agonist is added and there is more binding
  3. a plateau is reached as we either have full receptor occupancy or we have added all agonist and can’t get a higher biological response
84
Q

define Emax

A

the maximum response produced by an agonist

85
Q

define EC50

A

the concentration of agonist needed to give 50% of Emax

86
Q

How can we compare agonist drugs in the same biological system?

A

compare the profile of their concentration-response curves, Emax and EC50 values

87
Q

What does it mean if another agonist has a curve to the right?

A

it has a higher EC50, so a higher concentration of agonist is needed to give the same response, so the agonist is LESS POTENT that the other

88
Q

What do different EC50 values indicate?

A

different potencies for the receptor

89
Q

define partial agonist

A

an agonist that binds to a receptor but does not produce a FULL response - either poor efficacy or affinity

90
Q

What does the concentration-response curve look like for a partial agonist?

A

it will have an Emax below a full agonist and different EC50

91
Q

define inverse agonist

A

an agonist that reduces a biological response below basal levels

92
Q

What does the concentration response-curve look like for an inverse agonist?

A

Emax is below basal level

93
Q

What is an example of an inverse agonist drug?

A

drugs that reduce heart muscle contraction -> heart has basal level of activity without any agonist present

94
Q

define biased agonism

A

when different agonists bind to the same effector but activate different second messengers and create a different reponse

95
Q

What is an example of biased agonism?

A

G protein-coupled receptors can signal through a G protein or arrestin

96
Q

define arrestin

A

proteins that regulate the signalling of G protein-coupled receptors

97
Q

define balanced agonist

A

an agonist that activates both pathways to the same level

98
Q

What are the 2 types of competitive antagonist?

A

reversible or irreversible

99
Q

define competitive antagonist

A

an antagonist competes with agonists for the same receptor binding site

100
Q

How do reversible antagonists work?

A

increasing agonist concentration can outcompete antagonist

101
Q

How do irreversible antagonists work?

A

they permanently bind to receptors, so no amount of agonist can dislodge it

102
Q

How do reversible antagonists affect concentration-response curves of an agonist?

A

curve to the right but still can reach Emax, as a higher concentration of agonist A is needed to give the same response

103
Q

How do reversible antagonists affect Emax and EC50?

A

Emax of the agonist stays the same, but EC50 of agonist increases

104
Q

How do irreversible antagonists affect concentration-response curves of an agonist?

A

curve will be lower and to the right

105
Q

How does an irreversible antagonist affect Emax and EC50 of an agonist?

A

Emax of agonist decreases, EC50 of agonist increase

106
Q

How do we measure antagonism?

A

using the Schild plot and PA2

107
Q

define Schild plot

A

a way to determine the nature and potency of an antagonist

108
Q

What are the axes on a Schild plot?

A

X axis -> log (concentration of antagonist)
Y axis -> log (dose ratio -1)

109
Q

What is the equation for dose ratio?

A

EC50 of agonist with antagonist / EC50 of agonist without antagonist

110
Q

How do you determine the pA2 value?

A

pA2 vaule is where the line on the Schild plot intersects the X-axis (remember it is negative log of concentration)

111
Q

What does pA2 measure?

A

antagonist potency

112
Q

What is the pA2 equation?

A

pA2 = log(dose ratio -1) - log[antagonist]

113
Q

What does a higher pA2 value indicate?

A

a more potent antagonist

114
Q

What is indicated if two antagonists give the same pA2 value?

A

they act through the same receptor

115
Q

Where do agonists and competitive antagonists bind on a receptor?

A

the orthosteric site

116
Q

What is the allosteric site and its function?

A

another site on the receptor -> other molecules can bind here and modify the effects of an agonist

117
Q

define affinity modulation

A

the process of altering how well the agonist binds to the orthosteric site

118
Q

define efficacy modulation

A

the process of altering how well the agonist activates the receptor

119
Q

define affinity allosteric modulator

A

a ligand that binds to a receptor and alters how well the AGONIST binds to the receptor at the orthosteric site

120
Q

What do positive affinity allosteric modulators do?

A

increase how well an agonist binds to the orthosteric site, and decreases the concentration needed for the same reponse

121
Q

What do negative affinity allosteric modulators do?

A

decrease how well an agonist binds to the orthosteric site, and increase concentration needed for the same response

122
Q

define efficacy allosteric modulator

A

a ligand that binds to a receptor and alters how well the agonist activates the receptor -> the full response of the agonist will be increased or decreased

123
Q

define allosteric agonist

A

an allosteric ligand that binds to a receptor and can cause a response on its own without need for an agonist

Pharmacy (16 decks)

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