II - Pharmacodynamics

Question 1

Specific molecules in a biologic system with which drugs interact to produce changes in the function of the system

Answer 1

receptors

Question 2

Receptors must be _____ in their ligand-binding characteristics.

Answer 2

selective

Question 3

Receptors must be _____ when they bind an agonist to bring about functional change.

Answer 3

modified

Question 4

Most receptors are

Answer 4

proteins

Question 5

Specific binding region of the macromolecules, high and selective affinity for the corresponding drug molecule

Answer 5

receptor/recognition site

Question 6

Translate the drug-receptor interaction into a change in cellular activity

Answer 6

effectors

Question 7

Some receptors are also

Answer 7

effectors

Question 8

Response of a particular receptor-effector system measured against increasing drug concentrations

Answer 8

Graded Dose-Response Curve

Question 9

Dose-Response Curve yields a _____ if plotted on a semilogarithmic axis.

Answer 9

sigmoid curve

Question 10

Efficacy (Emax) and potency (EC50) are derived from

Answer 10

Graded Dose-Response Curve

Question 11

Fraction of receptors bound by a drug plotted against the log of the drug concentration

Answer 11

Binding Affinity

Question 12

Concentration required to bind 50% of the receptors

Answer 12

Kd

Question 13

The smaller the Kd, the _____ the affinity of a drug for its receptor.

Answer 13

smaller Kd = greater affinity

Question 14

Maximal effect achievable with increasing concentration of the drug

Answer 14

Emax (Efficacy)

Question 15

Concentration of the drug wherein half of the maximal effect is achieved

Answer 15

EC50 (Potency)

Question 16

Maximum percentage of receptors with increasing concentration of a drug

Answer 16

Bmax (Efficacy)

Question 17

Concentration wherein 50% of receptors are occupied

Answer 17

Kd (Potency)

Question 18

Fraction of the population that responds at each dose against the log of the dose administered

Answer 18

Quantum Dose-Response Curve

Question 19

Median effective (ED50), median toxic (TD50) and median lethal (LD50) doses are derived from

Answer 19

Quantum Dose-Response Curve

Question 20

Therapeutic Index

Answer 20

TD50/ED50

Question 21

Maximal effect an agonist can produce if the dose is taken at very high levels

Answer 21

Efficacy

Question 22

Efficacy is determined by

Answer 22

the nature of the receptor and its associated effector system

Question 23

Efficacy is measured by

Answer 23

Graded Dose-Response Curve

Question 24

Denotes the amount of drug needed to produce a given effect

Answer 24

Potency

Question 25

Potency is determined by

Answer 25

the affinity of the receptor for the drug

Question 26

Capable of fully activating the effector system when it binds to the receptor

Answer 26

full agonist

Question 27

High affinity for the activated receptor conformation

Answer 27

full agonist

Question 28

Sufficiently high concentration result in all the receptors achieving the activated state

Answer 28

full agonist

Question 29

Produces less than the full effect even when it has saturated the receptors

Answer 29

partial agonist

Question 30

In the presence of a full agonist a _____ acts as an inhibitor.

Answer 30

partial agonist

Question 31

Do not provoke a biological response by themselves upon binding to a receptor

Answer 31

antagonist

Question 32

Blocks or dampens drug response in the presence of an agonist

Answer 32

antagonist

Question 33

Binds to receptors in a reversible way without activating the effector system

Answer 33

competitive antagonist

Question 34

Shifts the dose-response curve to the right (increased ED50) but same maximal effect is reached

Answer 34

competitive antagonist

Question 35

Effects are overcome by adding more agonist

Answer 35

competitive antagonist

Question 36

Binds to receptors in an irreversible way without activating the effector system

Answer 36

non-competitive antagonist

Question 37

Shifts the dose-response curve to downwards (decreased EC50)

Answer 37

non-competitive antagonist

Question 38

Binds to a different receptor producing an effect opposite to that produced by the drug it's antagonizing

Answer 38

physiologic antagonist

Question 39

Interact directly with the drug being antagonized to remove it or to prevent it from reaching its target

Answer 39

chemical antagonist

Question 40

Responsiveness diminishes rapidly after administration of a drug

Answer 40

Tachyphylaxis

Question 41

Frequent or continuous exposure to agonists often results in short-term diminution of the receptor response

Answer 41

Tachyphylaxis

Question 42

Drugs that Exhibit Tachyphylaxis

Answer 42

dobutamine, ephedrine, LSD, metoclopramide, calcitonin, nitroglycerin, nicotine, hydralazine, desmopressin

Question 43

Continuous activation may lead to depletion of essential substrates, reversed by repletion of missing substrates

Answer 43

Tolerance

Question 44

Response that is infrequently observed in most patients

Answer 44

Idiosyncratic Drug Response