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342 > drug-receptor interactions 1 > Flashcards

drug-receptor interactions 1 Flashcards

1
Q

the majority of drugs ____/____ normal physiological/ biochemical processes or ____ pathological processes

A

mimic/inhibit
inhibit

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2
Q

the magnitude of a pharmacological response depends on (3)

A

nature of drug molecule
number/ avaliability of drug targets
amount of drug interacting with target

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3
Q

pharmacodynamics is the interaction of a ____ and the interaction with its ____ to form a ____ ____

A

drug (L)
receptor (R)
ligand receptor complex (LR)

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4
Q

what is psilocybin

A

hallucinogenic component in magic mushrooms
prodrug (psilocin is active metabolite)
partial agonist

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5
Q

what is psilocin structurally similar to

A

serotonin - difference in placement of hydroxyl group

(therefore psilocin mimicks serotonin’s endogenous function)

binds to serotonergic receptors

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6
Q

example of drug interfering with body’s pathogenic process

A

beta lactams e.g. penicillin inhibits peptidoglycan inactivating enzymes called penicillin-binding proteins (PBPs) - formation of bacterial cell wall and osmotic pressure, causing to burst

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7
Q

what are full agonists

A

produce max. response which system is capable of if given enough of full agonist

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8
Q

drugs that end in mab

A

monoclonal antibody

e.g. trastuzamab

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9
Q

example where avaliability of targets impacts pharmacodynamics

A

trustuzamab can only be given to patients with an overexpression of HER2 receptor (overexpressed in breast cancer)

overexpression allows antibodies to interact with cancer and not healthy cells containing HER2

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10
Q

full agonists have ___ affinity and ___ efficacy to their target

A

variable
high

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11
Q

what is an example of a full agonist

A

morphine

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12
Q

what receptor does the full agonist morphine act on

A

mu opioid receptor (MOR) which is a GCPR for pain relief

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13
Q

in sufficient doses, what endogenous function would morphine produce the same effect as?

A

enkephalins - endogenous opioid receptor ligands

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14
Q

neurotransmitters like dopamine and serotonin are ____ while GABA is ____

A

excitatory
inhibitory

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15
Q

what is an example of an endogenous agonist

A

serotonin of serotonergic receptors

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16
Q

what is an example of an exogenous agonist (serotonergic receptors)

A

psilobycin (psilocin technically) of serotonergic receptors

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17
Q

what is the mu opioid receptor (MOR)

A

GCPR
for pain relief

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18
Q

what drug is more potent than morphine that also is a full agonist of mu-opioid receptor (MOR)

A

heroin (diamorphine/ diacetylmorphine)

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19
Q

how are potencies typically measured

A

by comparing EC50

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20
Q

compare the EC50s of morphine and heroin (diamorphine/ diacetylmorphine)

A

heroin has a smaller EC50 - less drug is needed to elicit the same response

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21
Q

if codeine has a potency of 0.1, how big of a dose is needed to be equivalent to 10mg of morphine?

A

100mg

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21
Q

if heroin has a potency of 3, how big of a dose is needed to be equivalent to 10mg of morphine?

A

3.33mg

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21
Q

if morphine has a potency of 1, how big of a dose is needed to be equivalent to 10mg of morphine?

A

10mg

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22
Q

if fentanyl has a potency of 100, how big of a dose is needed to be equivalent to 10mg of morphine?

A

0.1mg

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22
Q

if oxycodone has a potency of 1.5, how big of a dose is needed to be equivalent to 10mg of morphine?

A

6.67mg

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22
Q

what is a partial agonist

A

produces a response but not fully activates to full response, regardless of dose

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22
Q

partial agonists have ____ affinity and ____ efficacy

A

variable
variable

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22
Q

what are two examples of a partial agonist

A

buprenorphine

psilocybin

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23
Q

what does buprenophrine bind to

A

mu opioid receptor (MOR) - high affinity, partially activated

lower efficacy than methadone

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24
Q

what is buprenophrine used for

A

decrease doses to wean patients off methadone - opioid replacement therapy

if not weaned off, sudden withdrawal causes shock and potential death

opioid disorder can cause respiratory depression

25
Q

what are antagonists

A

bind with no effect - also called neutral antagonists

26
Q

antagonists have ____ affinity and ____ efficacy

A

variable
no

27
Q

what are the two types of antagonism

A

competitive and non competitive

28
Q

what is competitive antagonism

A

surmountable
prevents activation of receptor

structurally similar to agonist

orthosteric site binding

29
Q

what is non-competitive antagonism

A

insurmountable
as binds to separate allosteric binding site - no competition

only reversible if agonist added before antagonist covalently binds to receptor

30
Q

what is an example of a competitive antagonist

A

naloxone
can be used to reverse opioid effects during overdose e.g. respiratory depression (as naloxone spray)

31
Q

what does naloxone bind to

A

opioid receptors
prevents activation of mu opioid receptors MOR - would outcompete if administered with opioid

32
Q

what is an example of a non competitive antagonist (2)

A

ketamine
cyanide

33
Q

what does ketamine bind to

A

NMDA channel pore
vs
the agonist glutamate binds to the extracellular surface of NMDA

34
Q

how does naloxone work to reverse opioid overdose

A

naloxone outcompetes opioids (morphine) for binding to the opioid receptors at the same orthosteric site as they are structurally similar, and outcompetes already bound opioids

reverses overdose symptoms e.g. respiratory depression

35
Q

agonists and competitive antagonists bind to the ____

A

orthosteric site

36
Q

what is meant by a competitive antagonist being surmountable

A

the competitive antagonist’s effects can be overcome by increasing dose of agonist

37
Q

compare the dose response sigmoid curve of a agonist vs a competitive antagonist + agonist

A

antagonist shifts curves to right - more agonist needed to overcome antagonist

38
Q

the orthosteric binding site is also called the ____

A

ligand binding site

39
Q

what binds to the allosteric site

A

non competitive antagonists

40
Q

what do non competitive antagonists look like on a dose response sigmoid curve

A

shifts to right but does not reach maximal response

41
Q

how does cyanide work as a non competitive antagonist

A

C triple bond N
non competitive antagonist/ inhibitor of cytochrome c oxidase in ETC, inhibiting ATP production
insurmountable

due to smoke inhalation

treatment focused on intercepting cyanide before it reaches and covalently binds to receptor/ cytochrome c oxidase or displacing it

42
Q

what are allosteric modulators

A

bind to receptor to change receptor’s responses to drug/ stimulus

cannot cause a response alone, only act on response from stimulus

43
Q

what are the two types of allosteric modulators

A

negative allosteric modulator NAM - inhibit
positive allosteric modulator PAM - enhance

44
Q

what is a type of NAM

A

non competitive antagonism

45
Q

how do NAM/PAMs affect dose response curve

A

curve moves to the left as less agonist needed for same response (PAM)
right if NAM

46
Q

what is an example of a negative allosteric modulator (NAM)

A

GABA neurotransmitter

47
Q

what does GABA bind to

A

GABA a or GABA b

48
Q

what is GABA a

A

ionotropic receptor - activation causes receptor to open and allow ions to flow through receptor

49
Q

what occurs when GABAa is activated

A

Cl- ions flow into cell causing hyperpolarisation - inhibits action potential firing, signalling in brain

50
Q

GABAa is activated by ____ (2)

A

GABA binding at orthosteric site
allosteric modulation at BZD allosteric site (PAM)

51
Q

examples of GABAa PAMs

A

benziodiazepines, zolpidem, barbituates

52
Q

what impact do PAMs have on GABAa

A

increase affinity for GABA of GABAa receptor so channel remains open for longer, more Cl- enters neuron, inc hyperpolarisation - the neuron action potential activity is further inhibited

53
Q

what is an inverse agonist

A

inhibit agonist’s independent low-level signalling
dec response

54
Q

examples of an inverse agonist

A

anti histamine (histamine receptors work without histamine being bound)

beta-carboline derivatives at BZD receptor - reduce GABA transmission - lead to inc anxiety and seizure disorders

11-cis-retinal which binds to rhodopsin via a Schiff base linkage in the dark, which stabilises it and prevents it from constituent signalling, allowing the eye to remain adapted to the dark

55
Q

how do anti histamine drugs function

A

prevent histamine activating receptor and inhibit constitutive/ independent activity - less effect result

56
Q

what are superagonists

A

capable of producing maximal response beyond than capable max response - unknown how

57
Q

example of superagonist

A

gaboxadol of GABAa receptors

58
Q

a full agonist, if displayed as response vs log of conc, forms what

A

sigmoid curve

59
Q

flumazenil

A

bzd competitive antagonist of GABAa receptor - used to treat bzd overdose or after surgery using bzd

but, has some partial inverse activity in patients with panic disorders - decreases the activity of GABA-A receptors- inc risk of panic attacks

suggests response depends on patient physiology

60
Q

cinacalet

A

PAM
treating hyperpara thyroidism

targets calcium sensing receptor, inc its sensitivity to calcium so activates at low calcium levels

dec parathyroid hormone production

61
Q

maraviroc

A

NAM
treating AIDS

targets CCR5

by binding to an allosteric site on the CCR5 receptor, maraviroc alters its conformation, preventing the HIV virus from binding and gaining entry into the cell

dec risk of resistance as allosteric site less prone to mutation

62
Q

a low Kd refers to a ___ affinity

A

high

63
Q

an example where efficacy is relevant in treatment

A

to treat opioid overdose, the full agonist morphine is administered, then buprenorphine to wean off and avoid shock from withdrawal

64
Q

compare the ec50 between heroin and morphine

A

heroin has a smaller EC50 value than morphine, so has a higher potency

65
Q

compare the ec50 between formoterol and salbutamol

A

for asthma treatment - helps with bronchodilation

formoterol has a smaller ec50 value than salbutamol so has a higher potency

66
Q

what is formoterol

A

long-acting β₂-adrenergic receptor agonist (LABA)

asthma treatment

67
Q

what is salbutamol

A

short-acting β₂-agonist (SABA)

asthma treatment

68
Q

example of cyanide treatment

A

vitamin B12a binds to cyanide

forming cyonocobalamin, non toxic

cyanide thus unable to bind to receptor

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