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304 > Pharmacodynamic > Flashcards

Pharmacodynamic Flashcards

1
Q

receptor

A

a macromolecule whose biological function changes when a drug binds to it

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2
Q

affinity

A

measure of propensity of a drug to bind receptors; the force of attraction between drug and receptor

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3
Q

signal transduction

A

a cascade of events triggered by drug-receptor binding interaction to which target tissue responds

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4
Q

…. bonds are involved in the stereospecific interaction between a receptor and its ligand

A

multiple

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5
Q

in most cases, binding is…

A

transient (drug molecule binds, dissociates, binds again, so on)

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6
Q

each binding triggers a…

A

signal

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7
Q

drugs with a …. conc. will have a greater chance of binding

A

higher

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8
Q

ka=

A

k1/k2 (affinity constant)

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9
Q

kd=

A

k2/k1 (dissociation constant)

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10
Q

the lower the kd….

A

the more affinity the drug has for the receptor

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11
Q

Emax

A

maximal effect produced by a drug or efficacy of a drug

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12
Q

dose-response curve or log dose response graph?

A

log dose response is sigmoidal, compresses dose scale, proportionate doses occur at equal intervals, easier to analyze mathematically

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13
Q

EC50

A

dose of a drug that produces 50% of maximal (half max) response

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14
Q

efficacy/ intrinsic activity

A

ability of a bound drug to change the receptor in a way that produces an effect

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15
Q

some drugs posses …. but not….

A

affinity, efficacy

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16
Q

Kd

A

conc. of a drug that occupies 50% of the total number of receptors at equilibrium

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17
Q

agonist

A

a grud which binds to the receptor and produces an effect (has affinity AND intrinsic activity)

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18
Q

partial agonist

A

has affinity for receptor but less intrinsic activity (lower efficacy compared to an agonist acting at the same receptor, therefore lower Emax)

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19
Q

antagonist

A

a drug which binds, but does not activate the receptor (has affinity but no intrinsic activity)

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20
Q

At the presence of a full agonist, a partial agonist…

A

acts as an antagonist and blocks the full effect of an agonist

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21
Q

example of a therapeutic use of a partial agonist

A

buprenorphine

  • an opioid analgesic
  • lower abuse potential since lower level of physical dependence
  • safer than full agonist such as morphine
22
Q

antagonist properties of a partial agonist

A

-provide some activity and block endogenous full agonist at the same time

23
Q

clinical example of a partial agonist acting as an antagonist

A

pindolol for high blood pressure and abnormal heart rhythms

-reduce excessive stimulation due to norepinephrine in a person with high sympathetic nervous system activity

24
Q

competitive antagonism

A

a higher dose of agonist is required to produce the same effect
-can still produce maximal effect

25
Q

irreversible/non-competitive antagonism

A

even a higher dose of agonist cannot produce maximal effect

-Emax is depressed

26
Q

inverse agonist

A

some receptors have intrinsic activity even when no ligand is bound to them; when a ligand binds to them, their basal activity is reduced

27
Q

allosteric interaction

A

when a ligand binds to a site close to the site of an agonist on a receptor and maybe affecting the binding and/or response to the agonist.
-2 ligands on a single receptor

28
Q

example of an allosteric interaction

A

Benzodiazepine drugs potentiate the response to game aminobutyric acid (GABA) when they bind to GABA receptor

29
Q

If an antagonist binds to the same site as the agonist, but does so IRREVERSIBLY or PSEUDOIRREVERSIBLY…

A

it causes a shift of the dose-response curve to the right with progressive depression of the maximal response as [I] increases

30
Q

It is easier to treat overdose or poisoning caused by…

A

a competitive (reversible) receptor blocker as opposed to an irreversible inhibitor

31
Q

quantal dose response curve

A

indicates sensitivity of a given population to the doses of a drug for a given effect

32
Q

frequency distribution

A

each bar shows the # of people responding to that dose and excludes people responding to lower doses

33
Q

cumulative frequency

A

each bar shows the # of people responding to that dose and to lower doses

34
Q

therapeutic index =

A

TD50/ED50 or LD50/ED50

35
Q

a therapeutic index that has a …. ratio, the safer the drug

A

higher

36
Q

therapeutic window

A

reflects a plasma conc. range that provides efficacy without unacceptable toxicity; difference between minimum effective conc. for desired response and an adverse response

37
Q

ED50

A

effective dose in 50% of people

38
Q

TD50

A

toxic dose in 50% of people

39
Q

LD50

A

lethal dose in 50% of people

40
Q

4 fundamental signal transduction mechanisms

A
  • g protein coupled receptor systems (fast, half of all known drugs work through GPCR)
  • ion channel receptors (fastest)
  • enzyme receptors (meh)
  • nuclear receptors (slowest)
41
Q

g protein coupling uses energy in the form of..

A

GTP

42
Q

3 second messengers activated by GPCRs

A
  • cAMP
  • IP3
  • DAG
43
Q

enzyme receptors

A
  • receptor is a pair of separate proteins
  • an agonist cause them to interact and form a dimer
  • interaction phosphorylates tyrosine and receptor becomes an active enzyme
  • active receptor enzyme activates a number of other enzymes that interact with the active tyrosine
44
Q

ion channel receptors

A
  • receptor is a protein with a channel in the centre

- agonist causes channel to open and allow specific ions to cross cell membrane to other side

45
Q

ion channel receptor examples

A
  • nicotinic acetylcholine receptor (conducts Na+ ions which muscle depolarization and contraction)
  • GABA receptors (conduct Cl- ions which inhibit neurotransmission)
46
Q

nuclear receptors

A
  • receptors are mostly in the cell cytosol
  • agonist enters cell and binds to receptor
  • drug-receptor complex enters nucleus and stimulates even transcription which leads synthesis of new proteins and enzymes
47
Q

examples of nuclear receptors

A

steroid, retinoids, and thyroid hormones

48
Q

homologous desensitization

A

when a desensitization to one agonist desensitizes other agonists at the SAME receptor

49
Q

heterologous desensitization

A

when a desensitization to one agonist in one receptor causes desensitization of to other agonists at a different receptor

50
Q

agonists tent to… receptors

A

desensitize

51
Q

antagonists tens to …. receptors

A

up regulate (sensitize)

52
Q

how do antagonists up regulate receptors?

A

-they cause a withdrawal rebound effect when antagonist treatment is stopped suddenly (when more receptors become available for the agonist)

304 (7 decks)

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