Pharmacodynamics

Question 1

What is the drug receptor concept?

Answer 1

Drug effects result from interaction with specific sites (receptors) on or in cells

Question 2

What is the mechanism responsible for selectivity of drug action?

Answer 2

Receptor specificity

Question 3

What is the action of agonist drugs?

Answer 3

Activate receptor is the same manner as endogenous ligands

Question 4

What is the action of antagonist drugs? When will these have no effect?

Answer 4

Prevent binding of agonist to receptor. Will have no effect in the absence of an agonist.

Question 5

Drug receptor theory states that the response to a drug is proportional to what?

Answer 5

Proportion of receptors occupied by drug

Question 6

e/Emax = ?

Answer 6

[D]/EC50+[D]

Question 7

Why is a drug response curve relatively linear at low drug doses?

Answer 7

Response usually increases in direct proportion to the dose

Question 8

Why does a drug response curve level off at high drug doses?

Answer 8

Limit to the increase in response because “all” receptors are occupied

Question 9

What are the advantages of a log dose response curve?

Answer 9

Can plot a wide range of doses, straight line over therapeutic range of doses

Question 10

Define potency

Answer 10

Concentration (EC50) or dose (ED50) required to produce 50% of the individual drug’s Emax

Question 11

What does potency depend on?

Answer 11

Affinity (Kd) of receptors for binding the drug, efficiency of drug receptor complex to generate response

Question 12

What is the relationship between a drugs potency and the dose given?

Answer 12

Determines the dose of a drug that is given

Question 13

What relationship does maximal effect/efficacy describe?

Answer 13

Binding to the receptor and ability of the complex to initiate a response

Question 14

What is the most important determinant of a drugs clinical utility?

Answer 14

Efficacy

Question 15

What is a full agonist?

Answer 15

Initiates a full or maximal response

Question 16

What is a partial agonist?

Answer 16

Occupy same receptor as full agonist, but produce less than the max response

Question 17

Are potency and efficacy dependent on one another?

Answer 17

No

Question 18

What classifications of antagonist drugs exist?

Answer 18

Receptor and nonreceptor

Question 19

Where do receptor antagonist (pharmacologic antagonist) bind?

Answer 19

Same receptor as agonist

Question 20

Where do non-receptor antagonist bind?

Answer 20

Different receptor or agonist molecule directly

Question 21

Where do reversible competitive antagonist bind?

Answer 21

Active site of receptor, block receptor

Question 22

The reversible nature of antagonist binding allows the block to be overcome, how?

Answer 22

Increase agonist concentration

Question 23

What drug is a pharmacologic antagonist of norepinephrine?

Answer 23

Metoprolol

Question 24

What is the effect on pontency and Emax for a competitive reversible antagonist?

Answer 24

Potency decreases, Emax is unchanged

Question 25

Can antagonism by noncompetitive antagonist be surmounted by increasing agonist concentration?

Answer 25

No

Question 26

What is the effect on potency and Emax of a noncompetitive irreversible antagonist?

Answer 26

Decreases Emax, minimal effect on potency

Question 27

What is the mechanism of action for a noncompetitive antagonist ?

Answer 27

Binds irreversible or pseudoirreversible to active site to receptor or allosteric site

Question 28

What is a physiologic antagonist?

Answer 28

Activates or blocks a receptor that mediates a physiologic response opposite to agonist

Question 29

What is epinephrine a physiologic antagonist of?

Answer 29

Histamine

Question 30

What is the mechanism of action of chemical antagonists?

Answer 30

Prevents agonist from interacting with receptor via modification of sequestration of agonist