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34 Cards in this Set
- Front
- Back
In DRC, an increase in the drug dose increases the responses. What word can be used to describe this? |
monotonic |
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What is the shape of dose response curves? a) logarithmic b) linear c) exponential d) semi-logarithmic |
d. They are semi-logarithmic |
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What are the three phases of the semi-log DRC? |
Phase 1: The dose is too low to elicit a response Phase 2: The dose is high enough such that the response is graded and linear Phase 3: Increased doses do not lead to greater responses. Drug toxicity may incur with increased doses. |
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Define efficacy |
a measure of how effective a drug is at a given dose (x axis constant) |
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Define maximal efficacy |
The maximum effect (responses) a drug is capable of achieving |
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When comparing two drugs for maximal efficacy, what parameter on the graph are we looking at? |
Their relative heights |
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What does it mean to titrate the dose of a drug? |
Doctors start with a low dose of the drug, and slowly increase the dose of the drug while monitoring the patient's response |
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Define potentcy |
the amount of drug required to elicit a pharmacological response (y axis constant0 |
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T/F high potency means more therapeutically effective. |
False. |
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What must be true in order to compare drugs for their relative potencies |
They must produce the same pharmacological effect |
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Define ED50 |
Amount of dose required to produce an effect in 50% of respondents |
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Most drugs act on _________ |
cellular macromolecules |
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majority of drug targets are receptors but drugs also act on what three things? |
enzymes, ion channels, transport proteins
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t/f drugs typically mimic exogenous compounds in the body |
false. they typically mimic endogenous compounds in da body |
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name a drug that does not act on a cellular target |
antacids |
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describe the drug and the mechanism of action for antacid |
antacid is a drug used to provide symptomatic relief for certain GI disorders. it is simply a base that neutralizes the stomach acid |
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Define receptor |
a protein that a drug binds to that produces a measurable response |
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the majority of receptors are proteins that are able to translate __________ _________ into ___________ __________ |
the majority of receptors are proteins that are able to translate extracellular signals into biological responses |
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name the 4 most important receptor types |
1. ligand gated ion channels 2. g-protein couples receptors 3. enzyme linked receptors 4. intracellular receptors/transcription factors |
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Describe the function of ligand gated ion channels |
Ions cannot directly penetrate the cell membrane, they require ion channels. Certain ligands (i.e. drugs or endogenous molecules) can cause the control of the opening and closing of ion channels. The ligand, once bound to the receptor on the gated ion channel, opens the channel and allows ions to pass into the cell, producing an instantaneous change in function. |
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How does GABA function to cause sedation and relaxation. |
The GABA neurotransmitter (ligand) binds to receptors on the ligand gated ion channels and elicits an influx of chloride. |
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What drug class have a similar mechanism of action akin to that of GABA |
Benzodiazepines |
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50% of marketed drugs mediate their effects through which receptor? |
G-protein coupled receptors (GPCRs) |
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Name and describe the 3 components of GPCRs |
1. a 7 transmembrane spanning protein receptor, with a ligand binding domain 2. a 3 subunit G-protein 3. an effector molecule (such as an enzyme)
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describe the mechanism of action of GPCRs |
a ligand binds to the ligand binding domain on the 7 transmembrane protein receptor. this causes the G-protein to dissassociate from the receptor and bind to and activate the effector molecule, which produces an intracellular response. |
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Name 3 endogenous neutrotransmitters that mediate their effects by binding to GPCRs |
norepinephrine, serotonin, histamine |
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describe the structure of enzyme linked receptors |
they span the entire cell membrane. they have a ligand binding domain on the outside of the cell, and an enzymatic catalytic site on the inside of the cell. |
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Describe the mechanism of action of enzyme linked receptors with reference to insulin. |
Binding of insulin to the ligand binding domain on the outside of the cell causes enzyme-mediated (inside of cell) phosphorylation and activation of an intracellular effector molecule. This effector molecule causes an increase in the translocation of glucose transporters to the cell membrane, effectively leading to greater uptake of glucose. |
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how do ligands access transcription factors |
They must either directly penetrate the PM or become uptaken by a uptake transport protein |
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describe the function of intracellular receptors |
binding of a ligand to an intracellular receptor causes translocation of this complex to the nucleus and the binding to DNA. Binding to DNA initiates transcription of mRNA.
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What are 2 differences between transcription factors and the other 3 receptors? |
1. Transcription factors are receptors that are intracellular 2. Transcription factors take hours-days to see the ultimate effects of the ligand binding occuring |
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What is an important chemical property of ligands that bind to trans factors? Name 2 examples of these ligands. |
They must be super lipophilic. Testosterone and Estrogen. |
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what is a selective drug? |
a drug that will only bind to one receptor. |
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why is it that selective drugs may still have side effects? |
because even through the drug may bind to only one receptor, if the target center for therapy is in the brain, but the receptor is located in the brain and the intestine, then the drug will produce side effects in the intestine as well. |