Module 8

Question 1

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

Answer 1

Simple occupancy theory

Modified occupancy theory

Question 2

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

Answer 2

Simple occupancy theory

Question 3

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

Answer 3

when all the receptors are occupied

Question 4

What are the three statements of the modified occupancy theory?

Answer 4

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)

Question 5

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

Answer 5

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

Question 6

Attraction a drug has for its receptor

Answer 6

affinity

Question 7

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

Answer 7

high

low

Question 8

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

Answer 8

low

high

Question 9

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

Answer 9

Potency

Question 10

Describe the relationship between affinity and potency.

Answer 10

Proportional

Question 11

Ability of a drug to activate a receptor.

Answer 11

Intrinsic activity

Question 12

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

Answer 12

high

low

Question 13

Describe the relationship between intrinsic activity and efficacy.

Answer 13

A drug with a high intrinsic activity has high efficacy.

Question 14

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

Answer 14

Agonist

Question 15

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

Answer 15

Antagonists

Question 16

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

Answer 16

Partial agonist

Question 17

What are some examples of agonists?

Answer 17

NTs and hormones

Question 18

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

Answer 18

Affinity, intrinsic activity

Question 19

Does an agonist always increase a physiological response?

Answer 19

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

Question 20

Describe the difference in dopamine effects based on dosing.

Answer 20

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

Question 21

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

Answer 21

affinity

intrinsic activity

Question 22

How do antagonists generate their effect?

Answer 22

By preventing the binding of endogenous molecules and other agonist drugs

Question 23

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

Answer 23

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

Question 24

What are some examples of antagonist drugs?

Answer 24

Beta blockers
Anti-histamines
Gastric acid reducers
Opioid receptor blockers

Question 25

Describe the action of beta blockers

Answer 25

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

Question 26

Describe the action of anti-histamines.

Answer 26

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

Question 27

Describe the action of gastric acid reducers.

Answer 27

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

Question 28

Describe opioid receptor blockers.

Answer 28

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

Question 29

What are the different types of antagonists?

Answer 29

Competitive Irreversivle Allosteric

Question 30

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

Answer 30

Competitive antagonist

Question 31

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

Answer 31

irreversible antagonist

Question 32

Binding occurs at different site than the agonist

Answer 32

Allosteric antagonist

Question 33

How can the effect of the competitive antagonist be overcome?

Answer 33

By increasing the concentration of the agonist

Question 34

How do irreversible antagonist effect the dose response curve?

Answer 34

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

Question 35

How long does the effect of irreversible antagonists last for?

Answer 35

Until the receptor is replaced

Question 36

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

Answer 36

seldom

Question 37

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

Answer 37

Induces a conformational change

Question 38

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

Answer 38

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

Question 39

Agonists that have only minimal or moderate intrinsic activity

Answer 39

partial agonist

Question 40

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

Answer 40

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

Question 41

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

Answer 41

Tolerance

Question 42

What are the three types of tolerance?

Answer 42

Desensitization Metabolic tolerance Tachyphylaxis

Question 43

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

Answer 43

Desensitization

Question 44

Induction of drug metabolizing enzymes due to continuous drug exposure.

Answer 44

Metabolic tolerance

Question 45

Rapid decrease in the response to a drug

Answer 45

Tachyphylaxis

Question 46

Describe receptor upregulation.

Answer 46

Continuous exposure to an antagonist causing increased cell synthesis of receptors