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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
if oxycodone has a potency of 1.5, how big of a dose is needed to be equivalent to 10mg of morphine?
6.67mg
22
what is a partial agonist
produces a response but not fully activates to full response, regardless of dose
22
partial agonists have ____ affinity and ____ efficacy
variable variable
22
what are two examples of a partial agonist
buprenorphine psilocybin
23
what does buprenophrine bind to
mu opioid receptor (MOR) - high affinity, partially activated lower efficacy than methadone
24
what is buprenophrine used for
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
what are antagonists
bind with no effect - also called neutral antagonists
26
antagonists have ____ affinity and ____ efficacy
variable no
27
what are the two types of antagonism
competitive and non competitive
28
what is competitive antagonism
surmountable prevents activation of receptor structurally similar to agonist orthosteric site binding
29
what is non-competitive antagonism
insurmountable as binds to separate allosteric binding site - no competition only reversible if agonist added before antagonist covalently binds to receptor
30
what is an example of a competitive antagonist
naloxone can be used to reverse opioid effects during overdose e.g. respiratory depression (as naloxone spray)
31
what does naloxone bind to
opioid receptors prevents activation of mu opioid receptors MOR - would outcompete if administered with opioid
32
what is an example of a non competitive antagonist (2)
ketamine cyanide
33
what does ketamine bind to
NMDA channel pore vs the agonist glutamate binds to the extracellular surface of NMDA
34
how does naloxone work to reverse opioid overdose
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
agonists and competitive antagonists bind to the ____
orthosteric site
36
what is meant by a competitive antagonist being surmountable
the competitive antagonist's effects can be overcome by increasing dose of agonist
37
compare the dose response sigmoid curve of a agonist vs a competitive antagonist + agonist
antagonist shifts curves to right - more agonist needed to overcome antagonist
38
the orthosteric binding site is also called the ____
ligand binding site
39
what binds to the allosteric site
non competitive antagonists
40
what do non competitive antagonists look like on a dose response sigmoid curve
shifts to right but does not reach maximal response
41
how does cyanide work as a non competitive antagonist
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
what are allosteric modulators
bind to receptor to change receptor's responses to drug/ stimulus cannot cause a response alone, only act on response from stimulus
43
what are the two types of allosteric modulators
negative allosteric modulator NAM - inhibit positive allosteric modulator PAM - enhance
44
what is a type of NAM
non competitive antagonism
45
how do NAM/PAMs affect dose response curve
curve moves to the left as less agonist needed for same response (PAM) right if NAM
46
what is an example of a negative allosteric modulator (NAM)
GABA neurotransmitter
47
what does GABA bind to
GABA a or GABA b
48
what is GABA a
ionotropic receptor - activation causes receptor to open and allow ions to flow through receptor
49
what occurs when GABAa is activated
Cl- ions flow into cell causing hyperpolarisation - inhibits action potential firing, signalling in brain
50
GABAa is activated by ____ (2)
GABA binding at orthosteric site allosteric modulation at BZD allosteric site (PAM)
51
examples of GABAa PAMs
benziodiazepines, zolpidem, barbituates
52
what impact do PAMs have on GABAa
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
what is an inverse agonist
inhibit agonist's independent low-level signalling dec response
54
examples of an inverse agonist - 3
anti histamine (histamine receptors work without histamine being bound) beta-carboline derivatives at BZD receptor (which is part of GABA- A receptor complex) - reduce GABA transmission - lead to inc anxiety and seizure disorders - used in research 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
how do anti histamine drugs function
prevent histamine activating receptor and inhibit constitutive/ independent activity - less effect result
56
what are superagonists
capable of producing maximal response beyond than capable max response - unknown how
57
example of superagonist
gaboxadol of GABAa receptors
58
a full agonist, if displayed as response vs log of conc, forms what
sigmoid curve
59
flumazenil
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
cinacalet
PAM treating hyperpara thyroidism targets calcium sensing receptor, inc its sensitivity to calcium so activates at low calcium levels dec parathyroid hormone production
61
maraviroc
NAM - anti retroviral therapy 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
a low Kd refers to a ___ affinity
high
63
an example where efficacy is relevant in treatment
to treat opioid overdose, the full agonist morphine is administered, then buprenorphine to wean off and avoid shock from withdrawal
64
compare the ec50 between heroin and morphine
heroin has a smaller EC50 value than morphine, so has a higher potency
65
compare the ec50 between formoterol and salbutamol
for asthma treatment - helps wit bronchodilation salbutamol has a smaller ec50 value than formeterol so has a higher potency - needs to be higher to achieve therapeutic effect in short duration of action
66
what is formoterol
long-acting β₂-adrenergic receptor agonist (LABA) asthma treatment
67
what is salbutamol
short-acting β₂-agonist (SABA) asthma treatment
68
example of cyanide treatment
vitamin B12a binds to cyanide forming cyonocobalamin, non toxic cyanide thus unable to bind to receptor
69
compare potencies of hydromorphine and morphine and clinical meaning
hydromorphine is at least 5x more potent than morphine, so patients can be switched to hydromorphine for analgesic effect if needed instead of inc morphine dose 1/5 of hydromorphine would have the same effect as of the full morphine dose (oral)

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