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Brain and Behavior Exam 2 > Lec 18 Opioid Analgesics and Antagonists > Flashcards

Lec 18 Opioid Analgesics and Antagonists Flashcards

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1
Q

25 y/o male with no past medical history presents to ER w/ 10/10 sharp left leg angle pain after falling off side of building,

was taking ibuprofen 400 ever 3 hrs with no relief, in ED has broken left tibia, planned for surgery/case

also in acute renal failure

which do you give
A. oral oxycodone w/ acetaminophen [percocet]
B. IV ketoralac [NSAID]
C. IV morphine [opioid]
D. IV hydromorphone [opioid]
E. IV acetaminophen
A

D. IV hydromorphone [opioid] because safe for renal failure!

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2
Q

What type of receptors do endorphins act on?

A

mu

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3
Q

What type of receptors do enkephalins act on?

A

delta

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4
Q

what type of receptors do dynorphins act on?

A

kappa receptors

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5
Q

What are the types of opioid endogenous peptides?

A

endorphins/morphine
enkephalins
dynorphins

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6
Q

Where are mu receptors located?

A
  • predominately brainstem, arcuate nucleus, pituitary, immune cells
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7
Q

What is function of the 3 different types of mu receptors?

A

u1: analgesia
u2: respiratory drive, miosis, euphoria, GI motility
u3: vasodilation

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8
Q

What is general function of opioids on mu receptors?

A

supraspinal and spinal analgesia, resp depression, sedation, euphoria, decreased GI transit, physical dependence

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9
Q

what is general function of opioids on delta receptors?

A

supraspinal and spinal analgesia

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10
Q

what is general function of opioids on kappa receptors?

A

analgesia, psychomimetic effects of some opioids

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11
Q

Where are delta receptors located?

A

widely in CNS and immune

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12
Q

Where are kappa receptors located?

A

widely in CPS including spinal cord and hypothalamus

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13
Q

What is function of opioid receptors along the pain path?

A
  • direct action on inflamed/damaged peripheral cells
  • inhibition at spinal cord
  • inhibition in higher paths of brain
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14
Q

Where do opioids tend to distribute?

A

to highly perfused tissues –> lungs, brain, liver, kidneys, spleen

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15
Q

How are opioids metabolized?

A
  • converted to polar metabolites by liver

- excreted by kidneys

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16
Q

How are opioids absorbed?

A
  • well absorbed subcutaneously, intramuscularly, or orally

- because of first pass effect –> need higher dose for oral form to get therapeutic effect

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17
Q

At which receptors does morphine act?

A

selective to mu receptor

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18
Q

What is significance of morhpine’s effect on pupils?

A
  • opioids block activity of inhibitory GABAergic interneurons –> increased PNS
  • causes miosis [pupil constrict]
  • miosis = important sign of opioid intoxication
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19
Q

Do pupils constrict or dilate with opioid use?

A

constrict

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20
Q

What are clinical uses for morphine?

A
  • acute pain
  • chronic cancer related pain
  • anti-dyspneic [shortness of breath]
  • weakly antitussive/anti-diarrheal
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21
Q

What are 2 possible adverse affects associated with morphine metabolites

A
  • accumulation of 6-glycuronide associated wtih renal toxicity
  • accumulation of 3-glyc associated wtih neurotoxicity/seizures
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22
Q

What are main side effects of morphine?

A
  • sedation [at initiation or dose escalation, get tolerance w/in days/wks]
  • nausea [at initiation, tolerance w/in 7 days, give antiemetics]
  • constipation [no tolerance]
    other: delirium, dry mouth, urinary retention
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23
Q

why do you develop opioid tolerance?

A
  • upregulation of cAMP, failure of receptor recyclig
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24
Q

What is WHO 3 step ladder?

A

if pain should deliver drugs in this order:

step 1: for mild pain
–> NSAID and acetaminophen

step 2: low potency opioids for moderate
–> codeine, oxycodone, hydrocodone, oral morphine, or tramadol

step 3: stronger opioid for severe
–> morphine IV, hydromorphone, fentanyl, methadone

+ can give non-opioid adjuvant at any time for extra benefit

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25
Q

Which drugs are better choices for neuropathic pain?

A
  • methadone and non-opioids better for chronic neuropathic pain
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26
Q

Which 3 drugs best if pt with renal failure? which can you not use?

A
  • fentanyl
  • methadone
  • hydromorphone with lower dose/frequency

can’t use: morphine, codeine

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27
Q

Can you use morphine with kidney/liver disease?

A

not in renal failure or dialysis, can use with caution in stable cirrhosis

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28
Q

Can you use codeine with kidney/liver disease?

A

NOPE

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29
Q

Can you use oxycodone with kidney/liver disease?

A

yes but w/ caution, not preferred

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30
Q

can you use hydromorphone with kidney/liver disease?

A

preferred in kidney disease

caution in liver disease

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31
Q

Which drugs overall best with renal/liver disease?

A

fentanyl and methadone are preferred

hydromorphone also good for kidney but use with caution in liver disease

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32
Q

Can you use fentanyl in kidney/liver disease?

A

yes = preferred

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33
Q

can you use methadone in kidney/liver disease?

A

yes = preferred

34
Q

What do you have to take into account when switching one opioid to another?

A
  • calculate equianalgesic dose
    reduce for incomplete cross talk
  • reduce equal dose by 50%
35
Q

What is incomplete cross-tlak?

A
  • someone with tolerance for one opioid may not be as tolerant to another opioid
  • due to differences in :molec structure, way opioid interacts with pts receptors
  • only applies to rotation from one opioid type to another not from Iv to PO of same opioid
36
Q

56 yo male with history depression, family history alcoholism, chronic back pain after car accident 5 yrs ago

presents to pain clinica asking for refill on hydromorphone.
Says he is taking for last 2 months
- methadone
- hydromorphone for extra pain

The patient has developed:
A. Tolerance
B. Dependence
C. Opioid Use Disorder (addiction)
D. Pseudo-addiction
E. All of the above
A

s

37
Q

What is dependence?

A

development of withdrawal syndrome following dose reduction or administration of antagonist

38
Q

what is tolerance?

A

change in dose-response relationship induced by exposure to the drug and manifest as a need for higher dose to maintain effect

39
Q

What is opioid use disorder?

A

pattern of opioid use leading to clinically significant impairment or distress

40
Q

What is addiction?

A

compulsive use despite harm, craving, impaired control of drug use

41
Q

What is pseudo-addiction?

A

behaviors that look like addiction but are driven by pain and disappear with more adequate analgesia [ex. clock watching, excessive complaints]

42
Q

What is the biologic base for addiction?

A
  • mesolimbic pathway

- in general, addictive drugs increase dopamine in mesolimbic system

43
Q

What structures are involved in mesolimbic system?

A
  • ventral tegmental area [VTa]
  • nucleus accumbens
  • amygdala/hippocampus
44
Q

What is the mech of addiction specifically for mu opioids?

A
  • in VTa cause inhibition of GABAnergic –> disinhibition of dopamine neruons
  • in PAG, arcuate nucleus, and locus coeruleus cause release of endorphins that directly influence the nucleus accumbens [NA] in manner similar to that of stimulants
45
Q

What is the function of the mesolimbic dopamine path?

A
  • reward [motivation]
  • pleasure/euphoria
  • motor function [fine tuning]
46
Q

what is the function of the mesolimbic serotonin pathway?

A
  • mood
  • memory processing
  • sleep
47
Q 
What is the likelihood that a patient will develop opioid use disorder when taking opioids?
A. <1%
B. 5-10%
C. 10-25%
D. 25-33%
E. 50-66%
A

A. <1%

48
Q

What is rate of developing OUD [opioid use disorder/]?

A
  • for pts who take opioids for pain –> less than 1%
  • in cancer –> 0-7%

increased risk for pts with prior substance abuse

49
Q

What are risk factors for OUD?

A
  • biological [fam history of drug abuse, male]
  • social [poor social support, history of drugs]
  • psych [substance abuse, sexual abuse, comorbid psych disease]
50
Q

Which 3 opioids can you detect in standard urine tox screen?

A
  • coedeine
  • morphine
  • hydrocodone
51
Q

What are the 3 general approaches to OUD treatment?

A
  • psycho-social therapy
  • opioid agonist therapy [methadone or buprenorphine]
  • opioid antagonist therapy [naltrexone]
52
Q

Which drug do you use for opioid antagonist therapy?

A

naltrexone

53
Q

What two drugs can you use for opioid agonist therapy?

A

methadone

buprenorphine

54
Q

What is mech of methadone action?

A
  • full mu-opioid agonist

- NMDA glutamate receptor antagonist [anesthetic, analgesia of neuropathic pain]

55
Q

What are unique side effects of methadone?

A
  • prolonged QTc

- cardiac arrhythmia

56
Q

What is the clinical pain use for methadone?

A
  • chronic pain more than acute [bc long half life]

- neuropathic pain [bc NMDA antagonist]

57
Q

Is methadone safe to give in renal/liver disease?

A

yes

58
Q

Why does methadone work for opioid use disorder?

A
  • prevents withdrawal symptoms
  • normalizes most neuro-endocrine alterations found with chronic opioid use
  • oral use –> slow rate of increase in plasma/brain levels thus less euphoria than other opioids
59
Q

Which 2 opioids do you use preferentially for analgesia?

A

morphine

hydromorphone

60
Q

Which opioid do you use preferentially for dyspnea?

A

morphine

61
Q

Which opioid do you use preferentially for cough?

A

codeine

62
Q

Which opioid do you give preferentially for preanesthesia? why?

A

fentanyl

because it has a short duration of action (1-2 hrs)

63
Q

Which 2 opioids do you give preferentially for regional anesthesia?

A
  • morphine

- fentanyl

64
Q

Which opioid do you use preferentially for cardiovascular surgery? why?

A
  • high dose fentanyl

- it produces minimal cardiac depression

65
Q

Who is eligible for methadone as treatment for OUD?

A
  • > 18 yo who have been dependent on opioids for > 1 yr

OR can be less than 1 yr IF: pregnant, previously treated, or following prison release

66
Q

How long are you on methadone for OUD treatment?

A

months or yrs, depends on starting dose and speed of reduction

67
Q

What is the induction phase of OUD treatment? stabilization? maintenance?

A

induction: given when individual abstained from using opioids for 12-24 hrs
stabilization: when pt no longer experiencing cravings for drug of abuse
maintenance: when pt doing well on steady dose

68
Q

What is mech of action naltrexone?

A

opioid antagonist

69
Q

How does naltrexone differ from naloxone?

A

naltrexone: 2x as potent and longer lasting than naloxone, tolerance does not develop, can give 2-3x wkly

70
Q

What are side effects unique to naltrexone?

A

DVT
hepatitis
eosinophlic pneumonia

71
Q

What are challenges of using naltrexone?

A
  • not effective in absence of structured program

- contraindication: pts receiving opioid analgesics or pts with dependence or withdrawal

72
Q

Which type of OUD treatment has lower rate of birth issues?

A

buprenorphine

73
Q

which is least expensive OUD treatment?

A

methadone

74
Q

How do you manage pain while on OUD therapy [methadone vs buprenorphine vs naltrexone]?

A

methadone: slightly increase dose of opioids if tolerance

buprenorphine

  • if severe: consider changing to methadone or short acting opioid
  • if mild: use buprenorphine alone

naltrexone
- discontinue and switch to buprenorphine or methadone

75
Q

What are early symptoms of opioid withdrawal?

A
  • anorexia
  • anxiety/restlessness/depression/insomnia
  • craving + intense drug hunger
  • headache
  • tachycardia
  • lacrimation
  • goosebumps [piloerection]
76
Q

What are symptoms of late opioid withdrawal?

A
  • muscle/bone pain
  • ab pain
  • low fever, high BP
  • mydriasis
  • N/V
  • hot/cold flashes
  • muscle spasm
77
Q

Which opioids have shortest time to start withdrawal?

A
  • fentanyl
  • then hydromorphone
  • then oxycodone = heroin = morphine = hydrocodone
78
Q

Which drugs have longest time to start withdrawal?

A
  • methadone
  • then hydrocodone = morphine = heroin = oxycodone
  • then hydromorphone
79
Q

What is treatment for opioid withdrawal?

A
  • opioid agonist therapy [methadone is best choice]
  • non-opioid therapy
  • supportive [fluid resuscitation]
80
Q

Is mortality likely with opioid withdrawl?

A

No– mortality is very low!!

81
Q

What is best form of non-opioid therapy for opioid withdrawal?

A

clonidine [alpha-2 adrenergic]

Brain and Behavior Exam 2 (21 decks)

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