04- Potency, Efficacy and Therapeutic Index Flashcards Preview

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Flashcards in 04- Potency, Efficacy and Therapeutic Index Deck (47)
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1
Q

pharmacodynamics

A

the study of how drugs interact in the human body

2
Q

true or false: all patient reacti the same to medications

A

false: Patient response to medications are highly individualized

3
Q

2 types of studies of pharmacodynamics

A
  1. quantal effects

2. graded effects

4
Q

frequency distribution curve

A

a graphical representation of the number of patients responding to a drug action at different doses (quantal)

5
Q

dose-response curve

A

Plot of data showing effects of various doses of a toxic agent on a group of test organisms (graded)

6
Q

quantal effects use what type of patient questions

A

yes/no (ex. did drug reduce BP by 20mmhg?)

7
Q

do frequency distribution curves indicate magnitude/max effect of drug dose?

A

no.

8
Q

Median effective dose (ED50)

A

the dose of a drug that produces a therapeutic response in 50% (refered to as standard dose)

9
Q

therapeutic index

A

Ratio of a drug’s LD50 (or TD50) to its ED50

10
Q

median lethal dose (LD50)

A

The drug dose that causes death in 50 percent of the experimental animals in which it is tested.

11
Q

Median toxic dose (TD50)

A

The drug dose that produces a specific adverse (toxic) response in 50 percent of the patients in whom it is tested.

12
Q

quantal

A

saftey of a drug

LD50/ED50 = # client would have to increase dose #’s before seeing specific adverse effect on average

13
Q

ex. which drug is safer? a drug with a quantal number 4 for increased HR as the adverse effect or a quantal number of 2 with an adverse effect of increased resp.

A

drug A - up to 3x dose without adverse effect, on average

14
Q

why is the quantal number so important? which demographic?

A

elderly patient often forget and double dose. the higher the quantal number, the larger the therapeutic window, the safer the drug :)

15
Q

therapeutic window

A

Range based on minimum effective therapeutic [ ] and minimum toxic [ ] for specific toxic effect

16
Q

high alert medications are:

A

medications with very low therapeutic windows that effective and toxic dose ranges overlap

17
Q

true or false: approx. 40% of patients need higher drug doses to reach desired effects

A

false: 25%

18
Q

dose-response curve

A

Demonstrates magnitude of biological response to a drug

Obtained by observing and measuring patient responses at different doses of drug

19
Q

dose response curves are used to determine:

A

therapeutic range
efficacy
potency

20
Q

3 phases of dose response curve

A
  1. few cells affected (not enough, little effect)
  2. linear relationship between amount administered and degree of response
  3. plateau - increasing dose has no effect (possible adverse)
21
Q

potency

A

Compares doses of 2+ drugs w respect to how much drug is needed to produce a specific response
usually based on median effective dose or concentration (ED50)

22
Q

efficacy

A

ability of drug to help client (exert more of a therapeutic response)

23
Q

what is a more important factor when assessing which drug is “better”: potency or efficacy

A

efficacy

24
Q

true or false: highly potent = lower affinity to receptor?

A

false

25
Q

association

A

drug binds to its receptor (k1 = Rate of drug-receptor complex formation)

26
Q

dissociation

A

k-1 = rate occurrence

27
Q

if k-1 is faster than k1 what does this mean in relation to association and dissociation and the drug’s affinity to a receptor?

A

association < dissociation

low affinity for receptor

28
Q

dissociation constant (Kd)

A

a measure of the affinity of the receptor for its ligand

k-1)/(k1

29
Q

true or false: a drug’s affinity for a receptor tells us how well drug binds to receptor and the action of the drug at the receptor

A

false: Doesn’t tell us anything about action of drug at receptor

30
Q

types of agonists:

A

Full, partial, inverse

31
Q

types of antagonists

A

reversible, competitive, non-competitive, and irreversible antagonists

32
Q

when do you use agonists vs. antagonists

A

agonist: if not making enough of ligand (replacement)
antagonist: too much of ligand or hormone

33
Q

Full agonist

A

Ability of a drug to produce 100% of the maximum response regardless of the potency
same effect as ligand (ex. dexamethasone for adrenal insufficiency)

34
Q

partial agonist

A

a drug that binds to a receptor and causes a response that is less than that caused by a full agonist (ex. aripiprazole for dopamine and management of bipolar or schizophrenia)

35
Q

true or false: efficacy of full agonist will always be higher than partial agonists

A

true

36
Q

inverse agonists

A

Bind to same receptor site as natural ligand, but induce opposite response to endogenous ligand (ex. GABA receptor. agonist have sedative response but inverse agonists have anxiogenic effects)

37
Q

when are inverse agonists viable?

A

Only occurs when receptors have an intrinsic (basal) level of activity

38
Q

true or false: inverse agonists have negative efficacy

A

true

39
Q

antagonist

A

bind to same receptor site ad endogenous ligand, but do not produce same effect (no efficacy)

40
Q

types of antagonists

A

reversible (competitive and non-competitive) and irreversible

41
Q

competitive agonist

A

Antagonist competes for same receptor binding site as endogenous ligand (linear drug response)

42
Q

non-competitive antagonist

A

binds to an allosteric (non-agonist) site on the receptor to prevent activation of the receptor

43
Q

clinical quality of non-competitive antagonists

A

poor. hard to predict response curve

44
Q

allosteric modulation

A

binding to another site on a receptor

45
Q

irreversible antagonist

A

A pharmacologic antagonist that cannot be overcome by increasing agonist concentration

46
Q

what does it mean for an irreversible antagonist to have its rate of dissociation (K-1) be 0?

A

Kd will be very low and its affinity to the receptor is very high

47
Q

ex. of irreversibel antagonists

A

biological weapons: Cholinesterase inhibitors (“nerve gases”)
drugs: Aspirin, omeprazole (management of GERD)