Opioids Flashcards

1
Q
  1. Opium
  2. Opioid
  3. Opiate
A
  1. mixture of alkaloids derived from the poppy plat soniferum
  2. any naturally occurring, semi- or synthetic compounds that bind to opioid receptors and share the properties of endogeneous opioids
  3. any naturally occurring opioid derived from opium
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2
Q

Good vs. Bad pain

A

Good - acute, nociceptive (when you touch something sharp), inflammatory (caused by inflammatory mediators), peripheral, protective

Bad - chronic, neuropathic (due to peripheral nerve damage, ex: diabetes), non-neuropathic/ non- inflammatory (no tissue/nerve damage, doctors cannot find the cause), sensitization…

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3
Q

The good pain pathway (4)

A
  1. Transduction (hot, cold, pressure, fire…)
  2. Conduction (to nerves)
  3. Transmission (to brain)
  4. Perception (withdrawal, pain avoidance, emotional reaction)
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4
Q

Reception and modulation of pain (10)

A
  1. something causes pain
  2. 1st neuron
  3. dorsal horn of spinal cord
  4. goes in opposite direction - 2nd neuron
  5. thalamus
  6. brain cortex

A fibers - myelinated - responsible for acute pain
C fibers - responsible for chronic pain
Descending neurons - a type of pain relief (NE and serotonin)
Ascending neurons - perception of pain

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5
Q

Mediators of:

  1. Facilitatory pathways
  2. Inhibitory pathways
A
  1. Glutamate, Aspartate, 5-HT

2. Opioids, GABA, 5-HT, NE

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6
Q
  1. Transduction mediators (nonciceptive terminals) (7)

2. Mediators are inhibited by:

A
  1. Capsaicin, Seronin, Histamine, Norepinephrine, Bradykinin, Prostaglandin, Canabinoids
  2. NSAIDS
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7
Q

Nociceptive terminals pic

A

LOOK AT IT

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8
Q

Endogenous Opioid Peptides

-3 families (names and from where they are synthesized)

A
  1. enkephalins –> met-ENK, leu-ENK
  2. endorphins –> alpha, beta, gamma END
  3. dynorphins –> DYN-A, DYN-B, alpha-neodynorphin, beta-neodynorphin
  4. synthesized from pro-enkephalin or pro-enkaphalin A
  5. synthesized from POMC (pro-opiomelacortin)
  6. synthesized from pro-dynorphin or pro-enkaphalin B
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9
Q

Opioid receptors (6)

A
  • G-protein coupled receptors
  • inhibit adenylate cyclase
  • active phospholipase C
  • facilitate opening of potassium channels at post-synaptic level
  • inhibit opening of calcium channels at pre-synaptic level
  • mu, delta, kappa
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10
Q

Opioid receptors

-what happens when they are activated (mu, delta, kappa table)

A
  • mu - analgesia in all levels, respiratory depression, pupil constriction, decrease GI motility, euphoria, sedation, physical dependence
  • delta - spinal analgesia, respiratory depression, decrease GI motility
  • kappa - spinal and peripheral analgesia, pupil constriction, decrease GI motility, dysphoria, sedation, physical dependence
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11
Q

Opioids

-area where they act in the CNS

A

-act on descending inhibitory pathways - medulla and midbrain in the periaqueductal area, rostral ventral medulla, dorsal horn

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12
Q

Morphine

  1. actions (10)
  2. therapeutic indications (5)
A
  1. analgesia, sedation, respiratory depression, decreases GI motility, decrease baroreceptor reflexes, histamine release from mast cells, pupillary constriction, euphoria, depression of cough reflexes, nausea and vomiting
  2. analgesia, euphoria, depression of baroreceptor reflexes (acute pulmonary edema), depression of cough, effects on GI tract
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13
Q
  1. Overdose triad
  2. main cause of death in intoxication
  3. treatment for intoxication
A
  1. pupillary constriction, comatose state, respiratory depression
  2. respiratory depression
  3. antagonists (ex: naloxone)
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14
Q

Tolerance vs. Dependence

A

Tolerance - adaptive up-regulation of adenylyl cyclase –> opioids inhibit adenylyl cyclase, so if you increase it’s concentration (ac) they will counteract each other

Dependence - satisfied by mu-receptor agonists (euphoria) and withdrawal syndrome happens due to mu-receptor antagonists

  • Physical dependence: withdrawal syndrome lasting for a few days
  • Psychological dependence: craving lasting for months or years
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15
Q

Methadone

  1. function
  2. pharmacokinetics
  3. other drugs
A
  1. used to relief withdrawal symptoms
  2. weak, long acting, mu-receptor agonist, half-life is >24h, little euphoric and less sedative effects, slow onset of action and recovery

Other drugs - much less physical or psychological dependence

  • Codeine - partial mu agonist
  • Pentazocine - mu antagonist, kappa agonist
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16
Q

Morphine and it’s analogues

  • pharmacokinetics (5)
  • unwanted effects (7)
A
  1. badly absorbed, metabolized by hepatic enzymes to glucoronide conjugates and undergo first-pass metabolism
  2. conjugates are eliminated by the kidney
  3. alcohol increases the serum levels of many opioids
  4. low lipophilic - fentanyl, heroin, methadone can cross the blood-brain barrier, morphine can’t
  5. all opioids can cross the placenta and cause neonatal respiratory depression

-sedation, dependence, respiratory depression, nausea and vomiting, histamine release, obstipation/ constipation, urinary retention

17
Q

Potency (3)

A
  • amount of a drug that is required to produce a given effect
  • the lower the concentration, the greater the potency
  • fentanyl is 80-100x more potent than morphine
18
Q

Morphine

-pharmacokinetics (7)

A
  • naturally occurring opiate
  • “gold standard”
  • can be administered: IM, IV, epidural, oral…
  • orally is badly absorbed (bio-availability 15-49%) - highly metabolized in liver and gut wall (first-pass metabolism)
  • conjugation with glucuronic acid –> morphine-3-glucuronide and morphine-6-glucuronide
  • morphine-6-glucuronide is 10-20x more potent than morphine
  • excreted in urine (accumulates in renal failure)
19
Q

Codeine

-pharmacokinetics (6)

A
  • administered orally or IM
  • low affinity for opioid receptors (partial mu agonist)
  • weak –> only used for moderate pain
  • anti-tussive and constipating effects
  • oral bio-availability is >50% (well absorbed)
  • metabolized to morphine by cytochrome CYP2D6
20
Q

Pure agonists

-names

A

morphine
methadone
fentanyl

-mu agonists

21
Q

Partial agonists

-names

A

codeine (weak)

-partial mu agonist

22
Q

Agonist-antagonists

-names

A

pentazocine

23
Q

Pure antagonists

-names

A

naloxone, naltrexone

-mu, delta, kappa antagonist

24
Q

Sufentanil vs. fentanyl (6)

A
  • is 5-10 times more potent than fentanyl
  • rapid recovery time after prolonged intravenous infusion
  • more lipid-soluble
  • better hemodynamic stability during cardiac anesthesia
  • histamine is not released
  • high doses may reduce the dose of neuromuscular blocker required
25
Q

Antagonists

  • names
  • characteristics
A

Naloxone - short acting (1-2h), block stress induced anesthesia, quick restore, relapse can happen if used for long time

Naltrexone - long acting (over 24h), we are sure that when it stops there will be no opioids left in the body

26
Q

Which opioid can cause pupil dilation and why?

A

Pethidine, because it is an anticholinergic substance

27
Q

Tramadol (7)

A
  • used to treat moderate to severe pain in adults
  • unwanted effects: constipation, nausea, vomiting, dizziness
  • half-life 4-6h
  • given orally, IM, IV
  • inhibition of noradrenaline uptake
  • weak mu-receptor agonist
  • well absorbed