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Flashcards in II - Pharmacodynamics Deck (44)
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1
Q

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

A

receptors

2
Q

Receptors must be _____ in their ligand-binding characteristics.

A

selective

3
Q

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

A

modified

4
Q

Most receptors are

A

proteins

5
Q

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

A

receptor/recognition site

6
Q

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

A

effectors

7
Q

Some receptors are also

A

effectors

8
Q

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

A

Graded Dose-Response Curve

9
Q

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

A

sigmoid curve

10
Q

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

A

Graded Dose-Response Curve

11
Q

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

A

Binding Affinity

12
Q

Concentration required to bind 50% of the receptors

A

Kd

13
Q

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

A

smaller Kd = greater affinity

14
Q

Maximal effect achievable with increasing concentration of the drug

A

Emax (Efficacy)

15
Q

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

A

EC50 (Potency)

16
Q

Maximum percentage of receptors with increasing concentration of a drug

A

Bmax (Efficacy)

17
Q

Concentration wherein 50% of receptors are occupied

A

Kd (Potency)

18
Q

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

A

Quantum Dose-Response Curve

19
Q

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

A

Quantum Dose-Response Curve

20
Q

Therapeutic Index

A

TD50/ED50

21
Q

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

A

Efficacy

22
Q

Efficacy is determined by

A

the nature of the receptor and its associated effector system

23
Q

Efficacy is measured by

A

Graded Dose-Response Curve

24
Q

Denotes the amount of drug needed to produce a given effect

A

Potency

25
Q

Potency is determined by

A

the affinity of the receptor for the drug

26
Q

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

A

full agonist

27
Q

High affinity for the activated receptor conformation

A

full agonist

28
Q

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

A

full agonist

29
Q

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

A

partial agonist

30
Q

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

A

partial agonist

31
Q

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

A

antagonist

32
Q

Blocks or dampens drug response in the presence of an agonist

A

antagonist

33
Q

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

A

competitive antagonist

34
Q

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

A

competitive antagonist

35
Q

Effects are overcome by adding more agonist

A

competitive antagonist

36
Q

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

A

non-competitive antagonist

37
Q

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

A

non-competitive antagonist

38
Q

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

A

physiologic antagonist

39
Q

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

A

chemical antagonist

40
Q

Responsiveness diminishes rapidly after administration of a drug

A

Tachyphylaxis

41
Q

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

A

Tachyphylaxis

42
Q

Drugs that Exhibit Tachyphylaxis

A

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

43
Q

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

A

Tolerance

44
Q

Response that is infrequently observed in most patients

A

Idiosyncratic Drug Response