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Neuro_week3 > Opioid analgesics > Flashcards

Opioid analgesics Flashcards

1
Q

Different classes of endogenous opioids

A

1) enkephalins
2) endorphins
3) dynorphin
4) endomorphin
5) nociceptins

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2
Q 
enkephalins 
structure 
terminated by?
found where?
ex =
A

pentaptides cleaved from pro-enkephalin
broken down by peptidases = short acting

found in brain and spinal cord

ex = methionine enkephalin

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3
Q

endorphins

uses =
made from =
found in =
ex =

A

NT and neurohormone

runner’s high, connects pain and stress systems

made from POMC

found in hypothalamic neurons and pituitary

ex = beta-endorphin has met-enkephalin at amino

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4
Q

dynorphin
made from?
target?
ex =

A

made from prodynorphin

target = kappa receptor

ex = dynorphin A= kappa selective

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5
Q

endomorphin

receptor?

A

mu-receptor selective

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6
Q

nociceptins

function?

A

regulate pain
related to true opioids but binds distinct receptors
opioid-like

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7
Q

opioids are ___ structure?

effects of which opioids antag by?

A

peptides

enkephalin, endorphin, dynorphin
antag by naloxone

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8
Q

opioid reeptors include …

all coupled to ..

A

mu
delta
kappa

all coupled to GTP proteins Gi/Go

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9
Q

mu receptor responsible for

endogenous agonist here

drug that acts here

A

analgesia,
resp depression

beta-endorphin
met/leu-enkephalin

morphine

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10
Q

delta receptor effect

agonist bind here

drugs act here?

A

analgesia

beta endorphin
met/leu-enkephalin

no drugs act here

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11
Q

kappa receptor
function

binds

drug act here?

A

spinal analgesia

binds dynorphin 1-17

pentazocine acts here

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12
Q

sigma receptor

target for?

A

opioid like drugs = dextramethorphan

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13
Q

all opioid recpetors are Gi/o protein coupled

overall function?
beta-gamma subunit binding VGCC causes…

binding GIRK causes

inhib G subunit causes…

A

overll decr neuronal excitability (hyperpol)

binds VGCC = inhib prsynap VG ca channel = inhib NT release

open GIRK K+ channel = hyperpol (pre or post but more post)

G subunit inhib AC, decr cAMP

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14
Q

opioid mechanism in ascending pathway

A

inhib of spinal cord/ascending pain path

inhib presynap excitatory NT release from primary afferents in dorsal horn (subst P, glutamate)

inhib of excitatory postsynap spinothal ascending output

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15
Q

opioid mechanism in descending pathway

A

activation of descending inhib systems in medulla, PAG, locus ceruleus mediated by 5-HT and NE

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16
Q

sites of action of opioids
behavioral effects

sign of acute toxicity

A

euphoria = abuse via mu receptors

dysphoria = hallucinations (kappa receptor and higher doses)

sedation, lethargy, confusion

toxicity = behavioral excitation (esp with meperidine, codeine from build up of toxic normeperidine)

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17
Q

define tolerance

which effects never develop tolerance

tolerance reverses after?

A

needing higher dose for same therapeutic benefit
affected by freq, dose, duration
still have pupil constriction
opioid receptor desensitizzation

No GI tract
No pupil constriction

reverses after withdrawal

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18
Q

define dependence

A

needing drugs to achieve physical and psych homeostasi and continued to prevent withdrawal

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19
Q

define withdawal

can be precipitated in addicts how?

A

opposite of opioid symptom

1) dilated pupil, insomnia, restlessness, rhinorrhea, sweating, diarrhea, nausea, cramp, chills

precipitate with antag or partial ag or mixed ag/antag

20
Q

how to treat withdrawal

A

antag
partial antag
mixed ag/antag
clonidine

21
Q

sites of action of opioids

gut

A

myenteric plexus = constipation

for GI surgery

22
Q

site of action of opioids

reinforcement regions in CNS

A

ventral tegmentum
nucleus accumbens = addiction-abuse)

mu receptors causing euphoria and abuse

23
Q

site of action of opioids

limbic (emotion) and motor

A

affective response to pain in amygdala, hippocampus, striatum

24
Q

Exogenous opioids
Phenathrines
mu ago

A

morphine (sched 2/IV/IM)
heroin (diacetylmorphine/more potent, rapid onset, same efficacy as morphine)
codeine (antitussive; CYP2D6 metab so not effective in everyone)
oxycodone (good oral bioavail)
oxycontin (sustained release)
hydrocdone (antitussive, weak analgesic)
tramadol = acts at mu and block MAO reuptake)

25
Q

Exogenous opioids
phenylpiperdines
mu agonist

A

meperidine/demerol (sched 2; faster onset and offset than morphine, less tolerance, less constip, not antitussive, but more toxic metab)

loperimide (anti-diarrhea, low water solubility)

fentanyl (short-acting, potent, short duration, surgical anesth, no histamine release)

26
Q

Exogenous opioids
phenylheptamines
mu agonist

A

methadone (used for opioid addict, decr withdrawal symptoms)

propoxyphene

27
Q

Exogenous opioids

mixed agonists/antagonists

A

buprenorphrine = partial mu (can cause mild withdrawal and cause analgesia and partially antag effects of morphine; used in maintenance therapy; patch)

pentazocine = kappa ag and mu antag (spinal analgesia with little resp depression, also precip withdrawal in people dependent on mu agonists 3)

butophanol = kappa ag and mu antag

nalbuphine = kapp ag and mu antag

28
Q

naloxone effect

naltrexone effect

alvimopam effect

A

competitive antag, short duration

longer duration, oral, treat alcoholism, reverse opioid overdose

block constipation without affect central analgesia

29
Q

adverse effects of opioids

A

1) respiratory depression even at normal doses- main cause of death (beware asthma, emphysema)
2) n/v at low dose in chemoreceptor trigger zone
3) pupillary constriction d/t excite edinger westphal = no tolerance ever
4) constipation = little tolerance
5) incr biliary pressure = smooth muscle contraction for bile stones tx with opioid + atropine BOTH
6) urinary retention
7) allergy via histamine release = anaphylaxis, itch, hives, red, HA; periph vasodilation and decr BP
8) mild effect on CV to decr pain and cardiac load, causes ortho hypotension
9) symptomatic cough suppression d/t inhib on cough center in medulla (codeine), less dose than analgesia/resp depression

30
Q

mechanism of resp depression in opioids

A

occurs even at analgesic doses
1) decr sensitivity of CO2 in brain stem resp centers

2) incr blood CO2
3) cerebral vasodilation
4) exacerbate head injury by incr ICP

31
Q

contraindication of opioids

A 
resp dysfunction (emphysema, asthma, OSA)
head injury (incr ICP from vasodilation)
hypotension (decr more with opiates)
shock 
hypothyroid
histamine release
impaired liver
32
Q

only resp function exception for opioids

A

pulm edema assoc with CV dysfunction

33
Q

DDI with opioids

A

synergic resp depression wtith barbiturates, phenothiazines (antipsych), MAOIs, tricyclics

can also induce excitation, delirium, seizures with MAOI and tricyclics

decr hypotensive effects with phenothiazines

34
Q

nociceptin binds which receptor

A

orphaninFC-ORL-opioid like receptor

35
Q

how do opioids affect subjective response to pain

A

decr subjective response

1) induce euphoria
2) “feeling pain” but response decr
3) involves limbic, locus ceruleus, ventral tegmentum

36
Q

compare opioids to local anesthetics

compare opioids to NSAIDS

A

opioids = more efficacious, selectively elim without alter sensations

opioids = better effecacious than NSAIDS

37
Q

opioid drugs relieve what type of pain better 1st or 2nd

opioids reduce ___ pain but less effective in treating ___ pain

A

relieve 2nd pain better than 1st

effective against nociceptive pain, less against neurogenic/neuropathic pain

38
Q

opioids can be combined with which antipyretics

A

acetaminophen, aspirin, ibuprofen

39
Q

why is dextromethorphan prone to abuse

A

additional action as dissociative agent via block of NMDA receptors

40
Q

combination of what for useful in chronic pain by potentiating inhib desc pain path

A

SSRI or NE reuptake inhibitor + opiate

41
Q

opioids are abs where?

undergo what type of metab?

rapidity of onset correlated with?

A

abs in GI tract

first pass hepatic metab

correlated with lipid solubility and abuse potential (IV>IM>oral)

42
Q

what method can u administer opioids while limiting resp depression

A

epidural or intrathecal

43
Q

metab of morphine how

A

conjugation with glucuronide in liver –> morphine-6-glucuronize 100x` more potent then excrete in urine

44
Q

chronic pain associated with terminal malignancy the responsibility of the physician is ___

A

to ensure that the patient is pain-free and comfortable

45
Q

Clinical uses of opioids

A

1) chronic for malignancy
2) painful diagnostics like local anesth and benzo
3) post-op pain
4) obstetrical anesthesia
5) patient-controlled analgesia
6) cough (lower doses) - separable from analgesic actions

46
Q

Rapidity of onset of opioids is correlated with

A

lipid solubility
abuse potential

heroin = fast + lipid soluble

Neuro_week3 (23 decks)

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