Opioids Flashcards

1
Q

Opioid

A

drug, natural or synthetic, that acts at opioid receptors

have diff affinities for diff sites and receptors- full/partial agonists, antagonists, etc.

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2
Q

Opiates

A

derived from opium poppy- contains opiate cpds including morphine, codeine

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3
Q

Morphine

A

prototype opioid
work on mu, kappa, delta G protein coupled receptors
-close Ca2+ channels, reducing evoked transmitter release (presynaptic)
-open K+ channels, hyperpolarizing membranes (postsynaptic)

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4
Q

mu receptors

A

produce analgesic, sedative, euphoric effects of opiates and untoward side effects

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5
Q

delta receptors

A

contribute to analgesia at spinal levels

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6
Q

kappa receptors

A

contribute to anagesia but primarily results in dysphoria

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7
Q

sigma receptor

A

not an opioid receptor- but contributes to dysphoric effects of opioids

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8
Q

Analgesic MOA

A

interact with body’s endogenous opioid peptide system for limiting pain

  • afferent pain transmission from periphery to CNS- opioid receptors in peripheral tissues, dorsal horn of spinal cord (pre and post synaptic) and ventral caudal thalamus
  • pain modulating descending pathways from CNS- periaqueductal gray matter (PAG), rostral ventral medulla, dorsal horn of SC

works both centrally and peripherally

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9
Q

CNS pharmacological effects

A

analgesia- changes perception and experience of pain (does not decrease sensation)
euphoria/dysphoria
sedation
miosis (cholinergic effect- pinpoint pupils)
nausea and vomiting through chemoreceptor trigger zone (CTZ)
truncal rigidity- impairs ventilation

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10
Q

peripheral pharma effects

A
dec gut motility- constipation
arterial and venous dilation
biliary colic via cholinergic
dec renal blood flow--> dec renal fxn
dec uterine tone
histamine release
endocrine alterations: inc adh, prl, somatotropin; dec LH
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11
Q

use of opioids

A
-no apparent maximal dose
acute or chronic pain
less effective for neuropathy 
decreases sensation of crisis in pulmonary edema or MI 
diarrhea
anesthesia/preop meds
cough- antitussive
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12
Q

toxicity of opioids

A
respiratory depression- #1 cause of death
dysphoric
constipation
nausea and vomiting
seizures
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13
Q

tolerance

A

starts with 1st dose and becomes clinically apparent in 2-3 weeks
-tolerance to different things develops at different times
-days- euphoria, resp dpression,
weeks- analgesia, sedation, nausea
months- cough suppression, antidiuressis

tolerance reverses in order it occurs

minimal or no tolerance to constipation, miosis, seizures

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14
Q

Withdrawal

A

abstinence syndrome- dysphoria, rhinorrhea, lacrimation, yawning, chills, anorexia, insomnia, anxiety, hostility
-not life threatening
compulsive drug seeking in dependent individuals due to avoiding withdrawal
craving can persist

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15
Q

relative efficacy

A

doses needed to produce a given effect

-fentanyl is 100 times more potent than morphine

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16
Q

high efficacy drugs

A

used for severe pain- trauma, post surgical, MI

morphine, methadone, meperdine, hydromorphone, oxymorphone

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17
Q

morphine

A

high efficacy
poor oral bioavailability
duration 4-5 hrs

glucuronidated–> M-6G which makes it more potent than morphine, but with poor BBB permeability

18
Q

methadone

A
high efficacy
long acting 6 hrs 
plasma 1/2 life 24 hrs 
good oral bioavailability
maintenance in opiate addicts
19
Q

meperdine

A
high efficacy
med acting 2-4 hrs 
anti muscarinic, may cause tachycardia
metabolized to active metabolite normeperidine 
pyschoactive
can cause seizures
20
Q

fentanyl

A
high efficacy
short acting 1-1.5 hrs
100x more potent than morphine, primarily acts in u receptors
poor oral bioavailability
transdermal dosage forms available
21
Q

alfentanil

A

high efficacy
very short acting 15-45 min
potent, parenteral only, brief painful procedures

22
Q

low to medium efficacy analgesics

A

partial agonist or drugs not tolerated at high doses
all adminstered orally
moderate pain- broken bones, dental procedures
often formulated with aspirin, acetaminophen, ibuprofen

23
Q

codeine

A

low efficacy, metabolized into morphine by cyp2d6

can also be used as an antitussive agent

24
Q

hydrocodone

A

moderate efficacy analgesic

25
Q

oxycodone

A

full agonist, moderate-high efficacy analgesic

26
Q

propoxyphene

A

v. low efficacy but withdrawn due to cardiac toxicity

27
Q

tramadol

A

low to med efficacy analgesic
inhibits NE and 5-HT reuptake
neupathic pain

28
Q

Partial or m ixed agonist-antagonist analgesic

A

believed to have less addictive potential and risk of respiratory depression
used for moderate to severe pain
used for opioid addiction

29
Q

buprenorphine

A

mu partial agonist

used for maintenance of opioid dependence as depot infxn or in combination with naloxone

30
Q

butorphanol

A

k agonist, mu partial agonist or antagonist

nasal spray

31
Q

nalbuphine

A

k agonist, mu antagonist

parenteral only

32
Q

pentazocine

A

k agonist, mu partial agonist or antagonist

33
Q

antidiarrheals

A

poor permeation of blood brain barrier
diphenoxylate
loperamide (otc)

34
Q

antitussives

A

codeine

doextromethorphan- otc (poor permeation of bbb)

35
Q

heroin

A

drug of abuse, no medical use

36
Q

naloxone

A

-IV, IM, SC, intranasal
-opioid antagonist for acute overdose
1-2 hr duration (likely to be shorter than the opioid that is being antagonized- so must be on the look out for opioid effects)
-high affinity for mu receptors, also antagonises k and delta receptors

IV admin can precipitate withdrawal symptoms

37
Q

naltrexone

A

used to prevent relapse in recovering addicts
oral
t1/2= 10 hrs

38
Q

opioid induced constipation

A

poor bbb penetration
inc risk of bowel perforation
methylnaltrexone
naloxegol

39
Q

contraindications

A

head injuries because they cause vasodilation increasing intracranial pressure
pregnancy- cause fetal addiction
impaired pulmonary fxn
hepato or renal compromised pts
endocrine disorders which can result in exaggerated and prolonged effects (hypothyroidism, addison’s)

40
Q

drug interactions- pure agonists and mix agonist-antagonists can cause

A

dec analgesia

can precipitate withdrawal symptoms

41
Q

opioid and antipsychotics

A

inc sedation and resp depression

inc risk of seizures

42
Q

MAOIs and opioids

A

inc risk of hyperpyrexic coma

htn