Opoids Flashcards
nociception define
the detection of painful stimuli
where are pain receptors found?
The receptor for pain are free (naked) nerve endings in the skin, muscle and viscera
substance P
Neurotransmitters for nociceptors include substance P. Inhibition of the release of substance P is the basis of pain relief by opioids
A-delta fibers
Fast sharp pain is carried by A-delta fibers. It has a rapid onset and offset and is well localized
A-delta fibers are thicker and myelinated
Myelinated
Transmit fast/sharp pain
Well localize , can point to pain
C fibers
Slow chronic pain is carried by C fibers. It is characterized as aching, burning or throbbing that is poorly localized.
C fibers are thinner and unmyelinated
Unmyelinated
Transmit slow/chronic pain
Diffuse , burning ,aching , throbbing sensation
Lamina II (and III)?
Lamina II (and III) is Substantia Gelatinosa
Entry of A- delta and C fibers into the posterior horn. where do the cell bodies lie? where do the fibers ascend or descend?
Cell bodies lies in dorsal root ganglia (DRG)
Fibers ascend or descend in track of Lissauer
Pathway for slow chronic pain
C fibers terminates in Lamina II and Lamina III (Substantia Gelatinosa ).
Interneuron transmit C fibers impulses to Lamina V from Lamina II and III.
Neurons leaving Lamina V cross immediately to the contralateral, lateral spinothalamic tract and ascend to brain
name the A- delta fiber neurotransmitter
A- fiber; the neurotransmitter is glutamate
name the C fiber neurotransmitter.
what does it bind to?
C fibers; the neurotransmitter is substance P which binds to NK-1(neurokinin-1) receptor on the postsynaptic membrane
Pathway for fast sharp pain:
A-delta fibers terminates in Lamina I , cross to the contralateral, lateral spinothalamic tract and ascend to the brain
Neuraxial (intrathecal or Epidural ) placement of Hydrophilic Opioids: what drug is this?
Morphine, a hydorphilic opioid, crosses lipid membrane slowly
tell me about intrathecal (spinal) placement.morphine
onset?
ventilation?
Slow onset and long duration of analgesia
No early depression of ventilation
Late depression of ventilation occur due to rostral (towards head) spread of CSF
Epidural Placement: morphine
tell me about onset
ventilation
Slow onset and long duration of analgesia
Early depression of ventilation (within 2 hrs) due to increase systemic uptake
Late depression of ventilation occur due to rostral spread
Neuraxial (intrathecal or Epidural ) placement of Lipophilic Opioids : what drug is this?
fentanyl, alfentanil, sufentanil –rapidly diffuse through lipid membrane
Intrathecal (Spinal) Placement of fentanyl..
Rapid onset and short duration of analgesia
Early depression of ventilation due to systemic uptake
Late depression of ventilation does not occur
Epidural Placement of fentanyl…
Similar as intrathecal (spinal) placement
if you add one of the fentanyl to a spinal- what will the patient experience as a side effect
they will get an itchy nose
3mg epidural=?spinal
0.3 spinal
Spinal Analgesia
which receptor??
Occurs when transmission of pain through substantia gelatinosa (L II) is suppressed
mu-2 is the dominant receptor
After IV administration, opioid acts on periventricular and periaquaductal gray — spinal analgesia
Supraspinal Analgesia
which receptor??
Opioids act on limbic system, hypothalamus and thalamus.
mu-1 is the dominant receptor
After IV administration of opioids
“ I feel pain but I don’t care”
Acupuncture releases what?
endorphins
descending neurons form?
The interneuron release
enkephalin inhibit release of what??
Dorsolateral tract modulates pain by??
periventricular and periaqueductal gray terminates on interneuron in substantia geletinosa (Enkephalin neurons)
enkephalin
Enkephalin inhibit release of substance P-spinal analgesia
by hyperpolarizing second order neurons
Three types of opioids receptors, located in CNS, nerve terminals, GIT and ANS
mu
kappa
delta
Opioids interact with opioid receptors and mimic the action of endogenous opioids which are?
(enkephalins, endorphins and dynorphins) and activate brain analgesia system
mu 2 responsible for?
mu-2 are responsible for respiratory depression and addiction
Supraspinal and spinal analgesia is primarily by
mu-receptors
k
(Kappa)
all of it
Analgesia (Spinal & Supraspinal)
Dysphoria
Low abuse
Potential
Miosis
Diuresis
delta
all of it
Analgesia (Spinal & Supraspinal)
Respiratory depression
Physical dependence
Constipation (mild)
mu 2
all of it
Analgesia (Spinal)
Respiratory depression(decrease sensitivity of resp. center to CO2)
Addiction
Constipation (marked) decrease motility and tone of GI muscles
increase CSF pressure (cerebral edema) C/I in head injury
mu 1
Analgesia (Supraspinal and spinal)
Euphoria
Low abuse potential
Miosis (PPP)
Bradycardia
Hypothermia
Urinary retention-C/I in BPH
Opioid Agonist
Morphine, fentanyl (sublimaze), codeine, heroin, methadone, meperidine (demerol), dextromehtophan, hydormorphone (Dilaudid) Sufentanil (sufenta), Remifnetanil ( Ultiva)
clinical use: cough suppression
(dexomethorphan),
diarrhea
loperamide, diphenoxylate