Relationship btw amount of drug and effect Flashcards Preview

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Flashcards in Relationship btw amount of drug and effect Deck (53)
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0
Q

what relationships are linear?

A

dose of drug and [drug] at target site

[drug-receptor complex] and response

1
Q

Dose response causal chain

A

dose of drug -> drug at target site -> drug-receptor complex -> response

2
Q

what relationships are non linear?

A

[drug] at target site -> [drug receptor complex]

3
Q

what is the dominant non linear relationship in the causal chain?

A

formation of the drug-receptor complex

4
Q

what does the drug-receptor complex determine?

A

the shape of the dose-effect and the concentration-effect relationships

5
Q

A plot of [D]free versus [R-D] is

A

hyperbolic

6
Q

A plot of log [D]free versus [R-D] is

A

sigmodial

7
Q

A plot of [D]free versus response is

A

hyperbolic

8
Q

A plot of log [D]free versus response is

A

sigmoidal

9
Q

The [drug] which causes 1/2 maximal response is called

A

EC50 and corresponds to the Kd if there is a linear relationship between [D-R] and response

10
Q

Potency refers to

A

EC50 of a drug

11
Q

when the assumption of linearity does not hold, the EC50

A

no longer approximates the Kd

12
Q

Spare receptors

A

when present, the EC50 will be much smaller than the Kd

13
Q

Tissue express “spare receptors” when

A

only a small fraction of the receptor population must be occupied by drug to give a maximal response

14
Q

The lower the Ec50, the

A

greater the potency

15
Q

A low Kd and high number of spare receptors increases

A

the potency of the drug

16
Q

Efficacy

A

refers to the maximal response of a drug

17
Q

the greater the maximal response,

A

the greater the efficacy

18
Q

The more effectively a drug engages signal-transduction systems in a cell per unit receptor occupied, the

A

greater is the efficacy of that drug

19
Q

best in class

A

Full agonist and any drug that generates a maximal response equal to the “best in class” is also referred to as “full agonist”

20
Q

Partial agonist

A

any drug that generates a maximal response less than that elicited by the “best in class”

21
Q

Even if Drug A is a full agonist and Drug B is a partial agonist, they can still the same what?

A

Potency

22
Q

Shape of dose versus Response

A

Hyperbolic

23
Q

shape of Log dose vs. Response

A

sigmoidal

24
Q

ED50

A

dose which causes 1/2 maximal response

affected by Kd and EC50 it is greatly influenced by apparent volume in which drug is distributed

25
Q

ED50 is never equal to

A

EC50 or Kd

26
Q

characteristics of surmountable antagonist

A

produces parallel shift in concentration-response curve of agonist
Full effect of agonist can be restored by increasing concentration of agonist

27
Q

Common mechanism of surmountable antagonism

A

competitive interaction between agonist (potency and efficacy) and antagonist (potent but no or little efficacy) at binding site on receptor

28
Q

The net effect of a competitive antagonist is to increase the apparent

A

Kd, or said differently to decrease the apparent potency of the agonist

29
Q

Addition of competitive antagonist causes

A

apparent shift in EC50 for the agonist

because takes higher concentration for a response

30
Q

Characteristics of insurmountable antagonist

A

produce non-parallel shift in concentration-response curve of agonist
full effect of agonist cannot be restored by increasing concentration of agonist

31
Q

Common mechanism of insurmountable antagonism

A

competitive but irreversible binding of antagonist to binding site on receptor
allosteric modulation of receptor by antagonist so as to attenuate coupling of receptor to signal transduction
blockade of signal transduction “downstream” of receptor

32
Q

Quantal effect

A

is an effect that is either present or absent

33
Q

Quantal concentration

A

or dose response curve is a plot of concentration or dose versus % patients in the population who exhibit the quantal response at the given concentration or dose

34
Q

we represent the effect of a drug in an Individual as a concentration or

A

dose response curve in which the graded effects of the drug are related to concentrations or doses of the drug

35
Q

we represent the effect of a drug in a Population as a concentration or

A

dose response curve in which the Quantal effect of the drug is related to concentrations or doses of the drug

36
Q

If quantal response happens to be death then ED50 is called

A

LD50

37
Q

Although both graded and quantal relationships have ED50s and EC50s, the parameter are

A

NOT the same for graded and Quantal relationships

38
Q

Graded relationships

A

Ed50s and EC50s indicate doses and concentrations that cause 1/2 maximal response in a given individual

39
Q

Quantal relationships

A

ED50s and Ec50s indicate doses and concentrations that cause 1/2 of the population to respond

40
Q

Since the log dose-response curve is sigmoidal, increasing

A

the dose of a drug when the response is submaximal will enhance the therapeutic effect

41
Q

Since the log dose-response curve is sigmoidal, increasing

A

the dose of a drug when the response is maximal will not improve the therapeutic effect but may subject the patient to toxicity

42
Q

The log dose-response curve is sigmoidal, regardless of whether the

A

“response” is therapeutic or toxic

43
Q

The safety of a drug can be assessed by examining the log dose-response curves for

A

therapeutic versus toxic effects

44
Q

The more separation between the therapeutic log dose-response curves and the toxic log dose-response curves, the

A

safer the drug

45
Q

A drug with low potency and high efficacy may be better than a drug with

A

low efficacy and high potency

46
Q

Potency is a determinant of

A

how much of the drug must be given to obtain a “ceiling” effect

47
Q

Efficacy refers to the magnitude of

A

the “ceiling” effect

48
Q

In an antagonist is being employed to block the effect of an agnoist, it is important to know whether the antagonist is of

A

surmountable or insurmountable type

49
Q

Dose of insurmountable antagonist usually does not need upward adjustment as amount of

A

agonist in body increases

50
Q

Dose of surmountable antagonist must be increased if amount of agonist (endogenous or exogenous) in the patient

A

increases

51
Q

Graded dose/concentration relationships help to understand

A

how changing dose of drug will effect the degree of response of an individual patient

52
Q

Quantal dose/concentration relationships help to understand

A

how changing dose of drug will effect the % of your patients who will experience a defined response