Exam 1 - Drug-Receptor Interactions

Question 1

receptor-mediated mechanism

Answer 1

most drugs act via interactions with receptors

Question 2

non-receptor mediated mechanism

Answer 2

some drugs do not act by interaction with receptors (antacid)

Question 3

What do drugs bind to within the body?

Answer 3

endogenous components of cells recognize and bind to specific drugs

Question 4

endogenous

Answer 4

normally present within the body

Question 5

exogenous

Answer 5

from outside the body

Question 6

What is the importance of frug-receptor interactions?

Answer 6

alters the activity of the receptor and alteration of receptor activity produces the observed effect of the drug

Question 7

Emax

Answer 7

the maximum effect or response that a drug can produce when it binds to its target

Question 8

ED50

Answer 8

the dose of a drug the produces a therapeutic effect in 50% of the population

Question 9

TD50

Answer 9

the dose of a drug the produces a toxic effect in 50% of the population

Question 10

LD50

Answer 10

the dose of a drug the produces a lethal effect in 50% of the population

Question 11

efficacy

Answer 11

measurement of the magnitude of response a drug elicits

Question 12

potency

Answer 12

measurement of the amount of drug required to produce a certain response

Question 13

therapeutic index

Answer 13

ratio that compares the toxic dose of a drug its effective dose, indicating the safety margin of the drug
* T.I. = TD50 / ED50

Question 14

What does a high therapeutic index signify?

Answer 14

a wider margin of safety between therapeutic and toxic effects (good)

Question 15

What does a low therapeutic index signify?

Answer 15

a smaller margin of safety between therapeutic and toxic effects (bad)

Question 16

agonist

Answer 16

a drug that, by itself, produces a response

Question 17

antagonist

Answer 17

a drug that, by itself, produces no response but prevents the agonist response

Question 18

What is the general Emax of a full agonist?

Answer 18

biggest Emax

Question 19

What is the general Emax of a partial agonist?

Answer 19

lesser Emax

Question 20

What is the general Emax of an antagonist?

Answer 20

0 Emax

Question 21

What is the general Emax of an inverse agonist?

Answer 21

negative Emax

Question 22

intrinsic efficacy

Answer 22

refers to the ability of a drug to activate a receptor and produce a biological response once it binds
* indicates how effectively a drug can elicit its intended effect relative to other compounds at the same receptor

Question 23

competitive antagonist

Answer 23

binds reversibly to the same receptor site as an agonist without activating the receptor
* effect can be overcome by increasing the concentration of the agonist
* no change in Emax

Question 24

non-competitive antagonist

Answer 24

bind either to the same site or to a different site on the receptor, causing a change in receptor function
* CANNOT be reversed by increasing agonist concentration
* reduction in Emax

Question 25

What are examples of pharmacological antagonist?

Answer 25

• competitive antagonist
• non-competitive antagonist
• partial antagonist

Question 26

chemical antagonist

Answer 26

substance that directly interacts with an agonist or another drug in a chemical reaction
* neutralizing or inactivating it before it can bind to its receptor or exert its effect

Question 27

physiological antagonist

Answer 27

a substance that produces an opposite physiological effect to that of an agonist but acting on a different receptor
* counter agonists action through independent mechanism rather than direct competition for the same receptor

Question 28

receptor specific drug

Answer 28

interacts with only a single receptor sub-type
* rare

Question 29

receptor selective drug

Answer 29

interacts with several receptor sub-types but has a preference for one of them
* common

Question 30

additive effect

Answer 30

response to two drugs together is the sum of both responses

Question 31

synergist effect (potentiation)

Answer 31

response to two drugs together is greater than the sum of each response

Question 32

idiosyncratic drug response

Answer 32

unusual or atypical response seen in only a small % of people

Question 33

hypersensitivity

Answer 33

allergic response

Question 34

tolerance

Answer 34

decreased response
* takes hours/days to develop

Question 35

refractoriness

Answer 35

decreased response
* often used to mean no response at all, similar to extreme tolerance

Question 36

desired effects

Answer 36

effects that produce a therapeutic response

Question 37

side effects

Answer 37

undesired effects

Question 38

adverse effects

Answer 38

serious medical consequences

Question 39

toxic effects

Answer 39

causing damage to an organ or whole organism

Question 40

What are the four basic sources of side/adverse effects?

Answer 40

1. chemical properties
2. drug that interacts with multiple receptor types (dirty drugs)
3. drug that interacts with single receptor type but multiple subtypes of that receptor
4. drug that interacts with single receptor subtype but receptor is in multiple tissues or acts via multiple effectors

Question 41

What is a goal of pharmacology in regards to specificity?

Answer 41

eliminate undesirable effects by increasing receptor specificty of drugs