Pharmacodynamics (Exam 1) Flashcards

1
Q

Agonist

A

Activator

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2
Q

Antagonist

A

Inhibitor

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3
Q

Endogenous

A

Naturally made

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4
Q

Xenobiotics

A

Synthetically made

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5
Q

Drug Targets

A
  1. Receptors
  2. Enzymes
  3. Ion Channels
  4. Transports/Carriers/Pumps
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6
Q

Types of Receptors

A

Ligand-Gated Ion Channels (LGIC)
G-Protein Coupled Receptors (GPCR)
Enzyme-Linked Receptors
Intracellular Receptors

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7
Q

Affinity

A

Strength of attraction between drug and its binding site

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8
Q

Covalent

A

Strong and in many cases not reversible
Least Common

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9
Q

Electrostatic

A

Vary from relatively strong linkages to weaker hydrogen bonds to van der Waals
Most Common

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10
Q

Hydrophobic

A

Important for highly lipid soluble drugs

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11
Q

Drug Response

A

Result of chemical interactions between a drug and binding site

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12
Q

Receptors

A

Transmembrane proteins located within cell membrane

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13
Q

How do receptors work?

A

Bind to ligand and propagate a signal leading to effect/response

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14
Q

Ligand

A

Molecule which produces a signal by binding to a site on receptor

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15
Q

Receptor Mediated Messenger System

A

First Messenger - ligand
Signal Transducer - receptors
Effector - enzymes activated by signal transduction
Second Messenger - Signaling molecules that activate other targets, allows for signal amplification

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16
Q

Autocrine Signaling

A

Ligand originates from same cell

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17
Q

Autoreceptor

A

Receptors whose purpose is to bind their own ligand as negative feedback mechanism

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18
Q

Paracrine Signaling

A

Ligand originates from nearby cell

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19
Q

Endocrine Signaling

A

Ligand originates from distant cell and travels through bloodstream

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20
Q

Hormones

A

Ligands of endocrine system

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21
Q

Ligand Gated Ion Channels (LGIC)

A

Ligand binding causes conformational change that opens channel allowing ions (Na+, Ca2+, K+, Cl-) to pass through

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22
Q

LGIC for Na+ and Ca2+

A

Excitatory
Make cell more positive, closer to threshold potential

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23
Q

LGIC for Cl- and K+

A

Inhibitory
Make cell more negative, farther from threshold potential

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24
Q

Acetylcholine (LGIC)

A

Nicotinic Receptor
LGIC (Na+)

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25
Q

Serotonin (LGIC)

A

5HT3 Receptor
LGIC (Na+)

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26
Q

Glutamate (LGIC)

A

NMDAR Receptor –> LGIC (Ca2+)
AMPAR Receptor –> LGIC (Na+)

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27
Q

GABA (LGIC)

A

GABA-A Receptor
LGIC (Cl-)

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28
Q

G-Protein Coupled Receptors (GPCRs)

A

Receptor bound to G-protein and leads to G-protein activation

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29
Q

Gs GPCRs

A

Activates adenylyl cyclase (AC)

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30
Q

Gi GPCRs

A

Inhibits adenylyl cyclase (AC)

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31
Q

Gq GPCRs

A

Activates phospholipase C (PLC)

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32
Q

What determines if receptor is Gs, Gi, or Gq?

A

The alpha subunit of G-protein

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33
Q

Gs Signaling Pathway

A

AC is activated and converts ATP to cAMP
cAMP acts as second messenger –> activates cAMP dependent protein kinases
Kinases phosphorylate other proteins

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34
Q

Gi Signaling Pathway

A

AC is inhibited
Sometimes K+ channels opened

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35
Q

Gq Signaling Pathway

A

Phospholipase C (PLC) is activated and converts PIP2 into DAG and IP3
DAG and IP3 act as second messengers
DAG activates PKC which activates other enzymes
IP3 causes Ca2+ release from intracellular storage
Ca2+ activates calmodulin –> other enzymes

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36
Q

Acetylcholine (GPCR)

A

M1, M3, M5 Receptor –> GPCR Gq
M2, M4 Receptor –> GPCR Gi

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37
Q

Norepinephrine/Epinephrine (GPCR)

A

alpha-1 receptor –> GPCR Gq
alpha-2 receptor –> GPCR Gi
beta1-3 receptor —> GPCR Gs

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38
Q

Dopamine (GPCR)

A

D1, D5 Receptor –> GPCR Gs
D2, D3, D4 Receptor –> GPCR Gi

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39
Q

Serotonin (GPCR)

A

5HT1, 5 Receptor –> GPCR Gi
5HT2 Receptor –> GPCR Gq
5HT4, 6, 7 Receptor –> GPCR Gs

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40
Q

Endogenous cannabinoids (GPCR)

A

CB1, CB2 Receptor –> GPCR G1

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41
Q

Endogenous opioids (GPCR)

A

Mu, delta, kappa Receptors –> GPCR Gi

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42
Q

Which receptor works quicker? GPCR or LGIC

A

LGIC because there’s no second messenger system

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43
Q

Activation of which receptor leads to increase in cAMP?

A

Gs coupled receptors

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44
Q

Enzyme-Linked Receptors

A

Linked to an enzyme that mediates downstream signaling
Alter gene expression to produce effects –> slow onset and long duration

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45
Q

Receptor Tyrosine Kinases

A

Enzyme within receptor
Ligand binds to receptor –> Conformational change leads to dimerization –> Activates tyrosine kinase function –> phosphorylation of tyrosine residue -> receptor becomes activated and phosphorylates downstream proteins

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46
Q

Which ligand uses receptor tyrosine kinases?

A

Insulin

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47
Q

Cytokine receptors

A

Enzyme as separate protein
Enzyme binds non-covalently and becomes activated following ligand binding and dimerization

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48
Q

Which ligand uses cytokine receptors?

A

Growth hormone

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49
Q

Intracellular/Nuclear Receptors

A

Ligand must be lipid soluble to cross cell membrane
Nuclear receptors bind to DNA and regulate gene expression
Contain ligand binding domain (LBD) and DNA binding domain (DBD)

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50
Q

Type 1 Nuclear Receptors

A

In cytosol but enter nucleus after ligand binding

51
Q

Type 2 Nuclear Receptors

A

Remain in nucleus and ligand must enter to bind

52
Q

Which ligands use Type 1 Nuclear Receptors?

A

Sex hormones and glucocorticoids

53
Q

Which ligands use Type 2 Nuclear Receptors?

A

Vitamin D and thyroid hormone

54
Q

Onset and Duration of LGIC

A

Onset: Milliseconds
Duration: Seconds

55
Q

Onset and Duration of GPCR

A

Onset: seconds to minutes
Duration: minutes to hours

56
Q

Onset and Duration of Kinase-Linked Receptors

A

Onset: 30 mins to an hour
Duration: Hours to days

57
Q

Onset and Duration of Nuclear Receptors

A

Onset: 30 mins to hours
Duration: Hours to days

58
Q

Regulation of Recepetors

A

Overstimulated receptor leads to decreasing sensitivity or number of receptors
Can occur due to high levels of endogenous ligand or drug

59
Q

Competitive inhibitor

A

Bind to enzyme at same site as substrate

60
Q

Noncompetitive inhibitor

A

Bind to enzyme at different site and block reaction from occurring

61
Q

Uncompetitive inhibitor

A

Bind only to enzyme-substrate complex and block reaction form occurring

62
Q

Intracellular Enzyme

A

Phosphodiesterase (PDE) - responsible for breaking down cAMP and cGMP

63
Q

What is an example of competitive inhibitor of PDE5?

A

Sildenafil
Used to treat ED and pulmonary arterial hypertension

64
Q

Extracellular Enzyme

A

Acetylcholinesterase (AChE) - responsible for breaking down acetylcholine in synapse

65
Q

What is an example of competitive inhibitor of AChE?

A

Donepezil
Treatment of Alzheimer’s disease

66
Q

Voltage Gated Ion Channels (VGICs)

A

Change in voltage causes conformational change that opens channel and allows ions to pass through
Rapid Signaling

67
Q

VGIC fo Na+ or Ca2+

A

Excitatory
More positive cell and closer to threshold potential

68
Q

VGIC for Cl- or K+

A

Inhibitory
More negative cell and farther from threshold potential

69
Q

Ca2+ VGIC in Vasculature

A

Blocked by some blood pressure lowering drugs

70
Q

Na+ VGIC on Neurons

A

Blocked by some drugs used to treat epilepsy

71
Q

Transporters/Pumps/Carriers

A

Proteins that help bring small molecules across biological membranes

72
Q

Why are transporters different than channels?

A

Transporters have binding sites for transported molecules
Channels are simultaneously open to inner and outer membrane

73
Q

Serotonin Transporter

A

Uptake of serotonin from synapse into presynaptic neuron
(SSRIs) block transporter and increase serotonin levels in synapse

74
Q

A drug binds to receptor located in the cytosol. Then, the drug-receptor complex travels to nucleus and enhances transcription. What kind of receptor is this?

A

Nuclear Receptor

75
Q

Drug Receptor Theory

A

Formation of drug-receptor complex leads to biological response

76
Q

Assumptions of Drug Receptor Theory

A

Reversible manner
Increase in drug concentration increase response, visa versa
Max response achieved when receptors saturated
Drugs competing with endogenous ligand

77
Q

What receptor does norepinephrine activate?

A

Beta1 receptors on the heart leading to increase in heart rate

78
Q

What receptor does acetylcholine activate?

A

M2 receptors in the heart leading to a decrease in heart rate

79
Q

Full agonist

A

Produces same maximum response as endogenous ligand

80
Q

Partial agonist

A

Produces lower maximum response than endogenous ligand

81
Q

A partial agonist acts as net agonists when…

A

…endogenous ligand concentrations are low

82
Q

A partial agonist acts as net antagonists when…

A

…endogenous ligand concentrations are high

83
Q

Competitive antagonist

A

Competes with endogenous ligand for binding site

84
Q

Non-competitive antagonist

A

Does not compete with endogenous ligand
Binds to allosteric site

85
Q

Reversible Antagonist

A

Binds reversibly to the receptor

86
Q

Irreversible Antagonist

A

Binds covalently to the receptor

87
Q

Inverse agonist

A

Reduces receptor activity below basal levels
Decrease constitutive activity

88
Q

Constitutive (Basal) Activity

A

Low levels of basal activity, even when there is no ligand present

89
Q

Positive Allosteric Modulators (PAM)

A

Bind to receptor at allosteric site and either increase receptor affinity OR increase receptor efficacy

90
Q

Negative Allosteric Modulators (NAM)

A

Bind to receptor at allosteric site and either decrease receptor affinity OR decrease receptor efficacy

91
Q

An ion channel has constitutive activity of 5 Ca2+ ions per second. The endogenous ligand for an ion channel causes the influx of 20 Ca2+ per second. If drug A binds to ion channel and cause the influx of 2 Ca2+ per second, what best describes drug A?

A

Inverse agonist

92
Q

Dose-response curve

A

Describes relationship between the dose/concentration of drug molecule and specific effect/response

93
Q

Efficacy

A

Measure of the maximum biological response produced by the drug

94
Q

Intrinsic Activity (IA)

A

Drug’s maximal efficacy as a fraction of maximal efficacy produced by endogenous ligand

95
Q

Saturation Binding Curve

A

Drug concentration versus number/percentage of receptors bound
Determine affinity

96
Q

Key parameters of saturation binding curve

A

Bmax and KD

97
Q

Dose Response Curve

A

Drug concentration/dose versus effect/response
Determine efficacy and potency

98
Q

Key parameters of dose response curve

A

Emax and EC50

99
Q

Bmax

A

Concentration of receptor sites (total number of receptors)

100
Q

KD

A

Drug concentration at which 50% of receptors are bound

101
Q

Relationship between KD and affinity

A

Smaller KD will have a higher binding affinity
Inversely proportional

102
Q

Emax

A

Maximum possible response that a drug can produce

103
Q

Relationship between Emax and Efficacy

A

Larger Emax will have higher efficacy
Directly proportional

104
Q

EC50/ED50

A

Amount of drug needed to produce 50% of the maximum response

105
Q

Relationship between EC50 and Potency

A

Smaller EC50 will have higher potency
Inversely proportional

106
Q

Relationship between slope and sensitivity

A

Steeper slope means higher sensitivity

107
Q

A shift to the right of dose response curve means…

A

…competitive antagonist

108
Q

A downward shift of the dose response curve means…

A

….non-competitive or irreversible antagonist
Changning Emax

109
Q

Spare receptor

A

When possible to elicit a maximal response at a concentration of agonist that does not result in occupancy of all available receptors

110
Q

Reasons for Spare Receptors

A
  1. Number of receptors may be greater than number of available downstream signaling molecules
  2. Duration of activation of signaling molecules is much greater than duration of drug-receptor interaction
111
Q

Selectivity

A

Degree to which drug acts on a specific tissue or target relative to others

112
Q

Tissue Selectivity

A

When receptor or target is only found in one type of tissue
Direct application may provide some selectivity

113
Q

Target Selectivity

A

Antibody drugs usually have high selectivity for target

114
Q

Temporal relationship between drug binding and effect

A

Drug remains bound: persistent effect until complex is destroyed or new molecules produced
Drug dissociates from target:
Terminate drug action, may persist due ti coupling molecule being active

115
Q

Idiosyncratic

A

Rare and unpredictable drug response

116
Q

Hyporeactive

A

Patients who have lower degree of drug response

117
Q

Hyperreactive

A

Patients who have higher degree of drug response

118
Q

Tolerance

A

Diminishing drug efficacy over time

119
Q

Tachyphylaxis

A

Tolerance that occurs rapidly after use of a drug

120
Q

Quantal Dose-Response Curve

A

Dose of drug versus percentage of individuals experiencing specific effect

121
Q

Therapeutic Index (TI)

A

Relationship between dose of drug that causes toxicity versus the dose that causes therapeutic effects
TI = TD50 / ED50

122
Q

Which of the following drugs would be considered the safest, based on therapeutic index?

A

Drug with TD50 of 20mg and ED50 of 1mg
20 / 1 = 20

123
Q

Therapeutic Window

A

Dose or concentration range which can treat disease effectively without having toxic effects
Larger the therapeutic window the safer the drug

124
Q

Therapeutic Drug Monitoring

A

Plasma concentrations are monitored to ensure serum concentrations within therapeutic window