Chapter 2: Pharmacodynamics

Question 1

A molecule to which a drug binds to bring about a change in function of the biologic system

Answer 1

Receptor

Question 2

A molecule to which a drug may bind without changing any function

Answer 2

Inert binding molecule or site

Question 3

Specific region of the receptor molecule to which the drug binds

Answer 3

Receptor site

Question 4

Receptor that does not bind drug when the drug concentration is sufficient to produce maximal effect; present if Kd > EC50

Answer 4

Spare receptor

Question 5

Component of a system that accomplishes the biologic effect after the receptor is activated by an agonist; often a channel, transporter, or enzyme molecule, may be part of the receptor molecule

Answer 5

Effector

Question 6

A drug that activates its receptor upon binding

Answer 6

Agonist

Question 7

An agonist that activates the same receptor as other drugs in its group but also causes additional downstream effects that are not seen with other agonists in the group

Answer 7

Biased agonist

Question 8

A drug that binds to the receptor without activating it and thereby prevents activation by an agonist

Answer 8

Pharmacologic antagonist

Question 9

A pharmacologic antagonist that can be overcome by increasing the concentration of agonist

Answer 9

Competitive antagonist

Question 10

A pharmacologic antagonist that cannot be overcome by increasing agonist concentration

Answer 10

Irreversible antagonist

Question 11

A drug that counters the effects of another by binding to a different receptor and causing opposing effects

Answer 11

Physiologic antagonist

Question 12

A drug that counters the effects of another by binding the agonist drug (not the receptor)

Answer 12

Chemical antagonist

Question 13

A drug that binds to a receptor molecule without interfering with normal agonist binding but alters the response to the normal agonist

Answer 13

Allosteric agonist, antagonist

Question 14

A drug that binds to its receptor but produces a smaller effect (Emax) at full dosage than a full agonist

Answer 14

Partial agonist

Question 15

Activity of a receptor-effector system in the absence of an agonist ligand

Answer 15

Constitutive activity

Question 16

A drug that binds to the non-active state of receptor molecules and decreases constitutive activity

Answer 16

Inverse agonist

Question 17

A graph of the increasing response to increasing drug concentration or dose

Answer 17

Graded dose-response curve

Question 18

A graph of the increasing fraction of a population that shows a specified response at progressively increasing doses

Answer 18

Quantal dose-response curve

Question 19

In graded dose-response curves, the concentration or dose that causes 50% of the maximal effect or toxicity. In quantal dose-response curves, the concentration or dose that causes a specified response in 50% of the population under study

Answer 19

EC50, ED50, TD50, etc

Question 20

The concentration of drug that binds 50% of the receptors in the system

Answer 20

Kd

Question 21

The largest effect that can be achieved with a particular drug, regardless of dose, Emax

Answer 21

Efficacy, maximal efficacy

Question 22

The amount or concentration of drug required to produce a specified effect, usually EC50 or ED50

Answer 22

Potency

Question 23

_____ is a drug capable of fully activating the effector system when it binds to the receptors.

• Has high affinity for the activated receptor conformation, and sufficiently high concentrations result in all the receptors achieving the activated state (Ra – Da)

Answer 23

Full agonist

Question 24

A _____ produces less than the full effect, even when it has saturated the receptors (Ra–Dpa + Ri–Dpa), presumably by combining with both receptor conformations, but favoring the active state.

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

Answer 24

Partial agonist

Question 25

Types of transmembrane signaling receptors:

_____ are the most common type of receptors in the body.

Answer 25

GPCRs

Question 26

Types of transmembrane signaling receptors:

_____ bind to the extracellular domain of molecules that incor- porate tyrosine kinase enzyme activity in their intracellular domains

• Insulin, epidermal growth factor

Answer 26

Membrane-spanning receptor- effector enzymes

Question 27

Frequent or continuous exposure to agonists often results in short-term diminution of the response, sometimes called _____

Answer 27

Tachyphylaxis