Pharmacodynamics 1 Flashcards

1
Q

Pharmacokinetics

A

study of what the body does to the drug

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2
Q

pharmacodynamics

A

study of the action of drugs on the body

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3
Q

drug nomencleture

A
  • chemical name
  • generic name
  • trade name
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4
Q

drugs often

A

mimic or block the action of our own signalling molecules

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5
Q

examples of natural drug sources

A

yew, fox glove, penicillium

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6
Q

receptor

A

generally used to describe the target molecules through which double physiological mediators produce their effects

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7
Q

protein targets of drugs

A

enzymes, transporters, ion channels, receptors

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8
Q

non protein targets of drugs

A

DNA, lipids

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9
Q

Principles of drug action

A

binding, agonism/antagonism, receptor classification, second messengers/signal amplification

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10
Q

4 receptor families

A

ligand gated ion channels
G protein coupled receptors
Kinase linked
nuclear receptors

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11
Q

ligand gated ion channels

A

ionotrophic receptors
passageway through membrane
conformational change
fast siganlling

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12
Q

example of ligand gated ion channel

A

nicotinic acetyl choline receptor

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13
Q

GPRC

A

Metabotrophic

protein with multiple subunits

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14
Q

example GPRC

A

post synaptic muscaranic acetylcholine receptor

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15
Q

kinase linked

A

inside the membrane
gene transcription and protein synthesis
response takes hours

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16
Q

example kinase linked

A

cytokine receptor - insulin receptors

“metabolic change”

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17
Q

Nuclear receptors

A

action in the nucleus - may not be specifically located in the nucleus
hours
gene transcription and protein synthesis

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18
Q

example of nuclear receptor

A

hormone - lipophilic eg oestrogeen receptor

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19
Q

Is a drug ever 100% specific?

A

no - only selective for the receptor over another

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20
Q

Specificity

A

the ability to identify the true negatives

eg 100% - correctly identify all the patients without the disease

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21
Q

Can therapeutic dose affect specificity?

A

yes - which receptors are activated

side effects at higher doses

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22
Q

binding is …. in 99% of situations

A

transient - on/off

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23
Q

rate of on and off

A

K↓1 and K↓-1

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24
Q

higher affinity

A

will bind more readily to its receptor

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25
Q

endogenous ligand

A

binds toa receptor - produced in the body

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26
Q

what is K↓D

A

the dissociation constant which is a measure of the tendency of the drug-receptor complex to dissociate

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27
Q

[D] [R] [DR]

A

K↓1 forwards and K↓-1 reverse reaction

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28
Q

K↓D =

A

k-1 = [D] [R] =?

k1 [DR]

29
Q

1/K↓A

A

K↓D

30
Q

smaller the K↓D

A

the higher the affinity

31
Q

Fractional occupancy

A

how may of the receptors are bound out of all the receptors

32
Q

Dissociation constant from conc/occupancy graph

A

the conc. of the drug required to occupy 50% of the available receptors

33
Q

p↓A (fractional occupancy) =

A

([D] / K↓D)

[D] / K↓D + 1

34
Q

saturation binding experiments

A

radiojlabel the drugs - work out the affinity or K↓D of a receptor.

or density (Bmax) of receptor for a specific tissue

35
Q

what is Bmax

A

density of a specific receptor in a tissue

36
Q

saturation binding: TB, SB, NSB

A
TB = Total Binding (some to other receptors)
SB = Specific Binding
NSB = Non-specific Binding (to other receptor (control used))
37
Q

axis for saturation binding

A

x - conc

y - %total bound

38
Q

what is a Scatchard Plot?

A

showing the amount of receptor bound (X) against bound/free (Y)

39
Q

what line should you see in a Scatchard plot?

A

straight line

40
Q

what is the gradient equal to in a Scatchard plot?

A

-1/ KD

41
Q

what is the X intercept in a Scatchard plot?

A

Bmax - the total density (concentration) of receptors in a sample of tissue

42
Q

B (bound) =

A

Bmax [D]

[D] + KD

43
Q

how would you investigate competitive binding?

A

competing off the amount of radio labelled drug - compete for the receptors

fixed conc of drug A incubated with increasing conc of drug B

44
Q

IC50

A

concentration of an inhibitor where the binding is reduced by half

45
Q

Cheng prusoff graph

A

X - log (B) concentration (M)

Y = binding to protein (pmol/mg)

46
Q

what is Ki? (cheng prusoff)

A

the dissociation constant (KD) of the unlabelled drug

47
Q

what is KA - cheng prusoff

A

Dissociation constant (KD) of the radiolabelled drug

48
Q

Cheng prusoff equation - Ki =

A

IC50 / (1 + ( [A] / KA)

49
Q

does binding a drug to a receptor mean there will be a reponse?

A

no - antagonist (won’t have a response)

50
Q

agonist

A

activates a receptor to cause a response

51
Q

activation of a receptor leads to

A

a measurable response

contraction, ion flow, change in HR

52
Q

concentration response curves

A
X = concentration (M)
Y = response
53
Q

drugs effect is proportional to…

A

drug concentration

54
Q

EC50

A

concentration of drug required to bring about a response in 50% of the receptors (50% of maximal response)

55
Q

EC50 or Kd bigger?

A

EC50 is much less than the KD

56
Q

what would influence whether max effect is able to be achieved

A

whether it is a full or partial agonist

57
Q

reserve / spare receptors - maximal response

A

Often, not all receptors need to be occupied for max. effect

58
Q

graded agonis effect

A

full, partial or inverse agonist

59
Q

“Full” agonists

A

elicit 100% effect of the endogenous agonist

60
Q

Partial” agonists

A

elicit < 100% effect

61
Q

Inverse” agonist

does what?

A

reduce basal receptor activity

- moved the equilibrium back towards the resting state (reducing the effect)

62
Q

what must you be careful not to confuse an inverse agonist with?

A

antagonist - as they have zero efficacy - not exerting a biological effect - where as inverse agonists are exerting an effect

63
Q

Potency

A

concentration to observe a response - more potent need less to see a response

64
Q

Agonist Drug “Potency” involves:

A

affinity + efficacy

65
Q

what is a dose?

A

concentration given of a dog depending on weight

66
Q

how to you establish what dose to give?

A

quartal dose response curves.
looking at serried effect
histogram - normal distribution

67
Q

cumulative quantal dose response

A

ED 50

68
Q

ED50

A

the effective dose to produce a therapeutic effect