Module 8 Flashcards

1
Q

What are the two receptor theories that we use to describe drug receptor interactions?

A

Simple occupancy theory

Modified occupancy theory

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2
Q

The intensity of a drug’s response is proportional to the number of receptors occupied.

A

Simple occupancy theory

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3
Q

When does the maximal response occur according to the simple occupancy theory?

A

when all the receptors are occupied

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4
Q

What are the three statements of the modified occupancy theory?

A

1 - The intensity of a drug’s response is proportional to the number of receptors occupied
2 - two drugs occupying the same receptor can have different binding strengths (i.e. affinity)
3 - Two drugs occupying the same receptor can have different abilities to activate the receptor (i.e. intrinsic activity)

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5
Q

What does the modified occupancy theory also take into account, as opposed to the simple occupancy theory?

A

Drug’s affinity for it’s receptor and it’s intrinsic activity

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6
Q

Attraction a drug has for its receptor

A

affinity

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7
Q

Drugs with a _____ affinity are highly attracted to their receptor and therefore bind effectively even at _____ concentrations.

A

high

low

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8
Q

Drugs with a ____ affinity are weakly attracted to their receptor and therefore bind ineffectively to the receptor even at ______ concentrations.

A

low

high

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9
Q

The affinity of a drug is the primary determinant of a drug’s _______.

A

Potency

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10
Q

Describe the relationship between affinity and potency.

A

Proportional

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11
Q

Ability of a drug to activate a receptor.

A

Intrinsic activity

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12
Q

Drugs that have a ______ intrinsic activity cause intense receptor activation. Conversely, those with _____ intrinsic activity only minimally activate the receptor.

A

high

low

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13
Q

Describe the relationship between intrinsic activity and efficacy.

A

A drug with a high intrinsic activity has high efficacy.

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14
Q

A molecule that binds to a receptor and activates it. Mimic the action of endogenous ligands.

A

Agonist

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15
Q

Molecules that bind to a receptor but do not activate it.

A

Antagonists

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16
Q

Molecule that binds to the receptor but has minimal ability to activate it

A

Partial agonist

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17
Q

What are some examples of agonists?

A

NTs and hormones

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18
Q

Agonists can be thought of as having both _______ and ________ ______ since they are able to bind and activate a receptor.

A

Affinity, intrinsic activity

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19
Q

Does an agonist always increase a physiological response?

A

No, it may increase or decrease it, but will activate a receptor all the same

20
Q

Describe the difference in dopamine effects based on dosing.

A

Low dose - causes renal artery vasodilation
Moderate dose - binds to B1 adrenergic receptor - increases cardiac output
high dose - binds to alpha adrenergic receptor - renal artery vasoconstriction

21
Q

Antagonists can be thought of having _____ but no ______ ________.

A

affinity

intrinsic activity

22
Q

How do antagonists generate their effect?

A

By preventing the binding of endogenous molecules and other agonist drugs

23
Q

Explain how an antagonist can have no effect if no agonist is present.

A

Because in that case, it is not blocking anything, and thus cannot derive any pharmacological effect

24
Q

What are some examples of antagonist drugs?

A

Beta blockers
Anti-histamines
Gastric acid reducers
Opioid receptor blockers

25
Q

Describe the action of beta blockers

A

Block the binding of epinephrine to beta 1 receptors in the heart, slowing the HR

26
Q

Describe the action of anti-histamines.

A

Block the binding of histamine to H1 histamine receptors in the nasal mucosa, preventing allergy symptoms

27
Q

Describe the action of gastric acid reducers.

A

Block the binding of histamine H2 histamine receptors in the gut - decrease gastric acid secretion

28
Q

Describe opioid receptor blockers.

A

Block the binding of opioids to opiate receptors, useful for treating opiate overdose

29
Q

What are the different types of antagonists?

A

Competitive
Irreversivle
Allosteric

30
Q

Binding occurs at the same site as the agonist and is reversible.

A

Competitive antagonist

31
Q

Binding occurs at the same site as the agonist but is irreversible

A

irreversible antagonist

32
Q

Binding occurs at different site than the agonist

A

Allosteric antagonist

33
Q

How can the effect of the competitive antagonist be overcome?

A

By increasing the concentration of the agonist

34
Q

How do irreversible antagonist effect the dose response curve?

A

Effectively remove certain receptors and thus cause a downward shift (lower maximal response) as a result

35
Q

How long does the effect of irreversible antagonists last for?

A

Until the receptor is replaced

36
Q

Because irreversible antagonists are irreversible in nature, they are very ______ used in therapeutics.

A

seldom

37
Q

Binding of the allosteric antagonist does what to the agonist binding site?

A

Induces a conformational change

38
Q

Describe the effect of an allosteric antagonist on the dose response curve.

A

Since the agonist cannot bind to the site, and cannot overcome inhibition through increased concentration, a downward shift is observed

39
Q

Agonists that have only minimal or moderate intrinsic activity

A

partial agonist

40
Q

What is another word for partial agonist? Why is it named as such?

A

Partial antagonist - since it essentially blocks the maximal response from occuring

41
Q

When patients are continually exposed to a drug and the response to the agonist decreases.

A

Tolerance

42
Q

What are the three types of tolerance?

A

Desensitization
Metabolic tolerance
Tachyphylaxis

43
Q

The receptor is internalized into the cell or destroyed as a result of continuous exposure to a drug.

A

Desensitization

44
Q

Induction of drug metabolizing enzymes due to continuous drug exposure.

A

Metabolic tolerance

45
Q

Rapid decrease in the response to a drug

A

Tachyphylaxis

46
Q

Describe receptor upregulation.

A

Continuous exposure to an antagonist causing increased cell synthesis of receptors