02a: Pharmacodynamics

Question 1

The GABA receptor is a(n) (X)-gated (Y) (transporter/channel/ATPase).

Answer 1

X = ligand
Y = Cl (ion)
Channel

Question 2

T/F: Drug effect on enzymes is usually inhibitory.

Answer 2

True

Question 3

Cocaine (stimulates/inhibits) which processes?

Answer 3

Inhibiting;

Reuptake of serotonin, NE, and DA

Question 4

Local anesthetics work by (stimulating/inhibiting):

Answer 4

Inhibiting;

Voltage-gated Na channels

Question 5

List the two types of dose-response curves.

Answer 5

1. Dose-intensity (how much effect?)

2. Dose-frequency (how many affected?)

Question 6

In Dose-Intensity curve, what’s the y-axis?

Answer 6

% effect

Question 7

In Dose-Frequency curve, what’s the y-axis?

Answer 7

% subjects responding

Question 8

The mathematical model that describes [drug] and R occupancy can also be applied to dose and response if which conditions are met?

Answer 8

1. Drug:R bind in 1:1 stoichiometry

2. Drug effect proportional to drug binding

Question 9

EC50 is also measure of drug (X). What does it represent?

Answer 9

X = potency

[Drug] that gives 50% of max effect

Question 10

EC(max) is also called (X) of drug. What does it represent?

Answer 10

X = efficacy

Max effect of drug (achievable at high dose)

Question 11

T/F: EC50 is directly correlated to drug potency.

Answer 11

False - indirectly (higher EC50, lower potency)

Question 12

How well drug binds receptor is (potency/efficacy). How well drug produces effect is (potency/efficacy). Star the one that’s more relevant to clinicians.

Answer 12

Potency; efficacy*

Question 13

Increasing number of spare receptors will (increase/decrease) potency of drug.

Answer 13

Increase (decrease EC50)

Question 14

Chemical antagonist exerts its effect by:

Answer 14

Interacts with agonist to render it inactive (i.e. Etanercept)

Question 15

Pharmacokinetic antagonist exerts its effect by:

Answer 15

Accelerating metabolism/elimination of agonist

Question 16

Physiological antagonist exerts its effect by:

Answer 16

Activating mechanism that opposes agonist’s effect

Question 17

Competitive and noncompetitive antagonism are examples of which type of antagonism? This occurs at the level of (ligand/receptor/beyond).

Answer 17

Pharmacological;

Receptor

Question 18

Reversible competitive antagonist: how does dose-response curve change? And ED50?

Answer 18

Shift right;
Higher EC50 (reduced potency)

Question 19

Competitive antagonism (is/isn’t) surmountable, which means (X).

Answer 19

Is;

X = can overcome inhibition by increasing [agonist]; efficacy unchanged

Question 20

Non-competitive antagonism: (potency/efficacy) change in which way(s)?

Answer 20

Decrease efficacy (max effect); no change in potency (EC50)

Question 21

Irreversible competitive antagonism: (potency/efficacy) change in which way(s)?

Answer 21

Decrease efficacy (max effect); no change in potency (EC50)

Question 22

Why might a dose-effect curve be bell-shaped? Give an example.

Answer 22

Multiple receptors with different affinity and opposing effects;
Ex: Epi (low dose) binds beta2-R, vasodilation; Epi (high dose) binds alpha1-R, vasoconstriction

Question 23

Positive cooperativity (i.e. Hemoglobin) changes shape of dose-effect curve in which way(s)?

Answer 23

Steeper curve

Question 24

Spare receptors: you have (same/different) response with (same/different) receptor occupancy. How is the dose-response curve changed?

Answer 24

Same; different (less % occupancy)

Shifts left, same max

Question 25

Spare receptors: the (EC50/Kd) is greater than the (EC50/Kd). What does this mean?

Answer 25

EC50; Kd Greater apparent potency; reach 50% of max effect although less than 50% of receptors occupied by agonist

Question 26

K (active/inactive) is greater for agonists.

Answer 26

Inactive

Question 27

K (active/inactive) is greater for competitive antagonists.

Answer 27

Neither - equal

Question 28

Which agonist/antagonist would have K-active greater than K-inactive?

Answer 28

Inverse agonist (inhibits a constitutively active R with elevated basal response)

Question 29

(X) refers to joint effect of two drugs as algebraic sum of their individual effects.

Answer 29

X = summation

Question 30

(X) refers to joint effect of two drugs as being greater than algebraic sum of their individual effects.

Answer 30

X = Synergism

Question 31

(X) refers to phenomenon when inert drug increases effect/potency of another drug.

Answer 31

X = potentiation

Question 32

Benzos effect on GABA-R is example of (summation/synergism/potentiation).

Answer 32

Potentiation

Question 33

Tachyphylaxis refers to phenomenon when:

Answer 33

Effect of drug declines very rapidly (a type of tolerance)

Question 34

T/F: Quantal dose-response curves are scored in binary fashion.

Answer 34

True (threshold determines if effect is present/absent)

Question 35

List the types of quantal dose-response curves as well as the shape of the plots.

Answer 35

1. Incremental (bell-shape) | 2. Cumulative (sigmoidal)

Question 36

A steeper slope in cumulative quantal curve means (X). How would this plot look in incremental quantal curve?

Answer 36

X = less variability (in doses that produce effect) Tighter bell curve

Question 37

Therapeutic Index equation. (Larger/smaller) value is more favorable and indicative of safer drug.

Answer 37

LD50/ED50; Larger

Question 38

Standardized safety margin equation.

Answer 38

(LD1-ED99)/(ED99)

Question 39

Physiological antagonism: agonist and antagonist bind (same/different) receptor.

Answer 39

Different

Question 40

Inverse agonist: the two agonists bind (same/different) receptor.

Answer 40

Same