Pain and opioids

Question 1

Mechanism of action with opioid agonist

Answer 1

u = morphine
delta = enkephlin
k = dynorphin

Question 2

How do opioids work

Answer 2

modulate synaptic transmission by opening K+ channels and closing Ca++ channels. This decreases transmission and release of NE’s (NE, Ach, glutamate, and substance P.

Question 3

Clinical uses of morphine

Answer 3

cough suppression, pain, diarrhea, acute pulmonary edema, maintenance program for addicts

Question 4

Morphine toxicity

Answer 4

addiction, respiratory depression, PPP, constipation, sustained erection, urinary retention, pruritis (histamine release), sedation

Question 5

Respiratory depression requirements

Answer 5

oxygen, pulse ox, narcan close

Question 6

What is pruritis?

Answer 6

itching

Question 7

what type of patients are at risk with histamine release from opioids?

Answer 7

asthmatics - bronchoconstriction from histamine release

Question 8

What is nociception?

Answer 8

ability to perceive and detect noxious stimuli (pain)

Question 9

Slow pain fibers

Answer 9

C-fibers

Question 10

Fast pain fibers

Answer 10

delta fibers

Question 11

The receptors for pain?

Answer 11

free nerve endings in skin, muscle and viscera

Question 12

Delta fiber NT

Answer 12

glutamate

Question 13

C-fiber NT

Answer 13

Substance P

Question 14

Where do delta fibers terminate?

Answer 14

Lamina I, cross contralateral to lateral spinothalmic tract where they ascend to brain

Question 15

Where do C-fibers terminate?

Answer 15

Lamina II and III (substantia gelatinosa), neurons leaving lamina V cross immediately to contralateral to spinothalmic tract and then ascend to brain

Question 16

Name a hydrophillic drug

Answer 16

morphine - slow effects but long duration

Question 17

Name a lipophillic drug

Answer 17

fentanyl, alfentanil, sufentanil - fast action but short duration

Question 18

Spinal analgesia receptor and location

Answer 18

u-2 receptor and acts on periventricular and periaquaductal gray

Question 19

supraspinal receptor and location

Answer 19

u-1 receptor and acts on limbic system, hypothalamus, and thalamus

Question 20

Where do periventricular and periaquaductal gray terminate?

Answer 20

substantia gelatinosa (enkephalin neurons)

Question 21

Enkephalins inhibit release of?

Answer 21

substance P - spinal analgesia

Question 22

Where are the three types of opioid receptors located?

Answer 22

CNS, nerve terminals, GIT, and ANS

Question 23

u-1 receptor effects

Answer 23

euphoria, low abuse potential, miosis, bradycardia, hypothermia, urinary retention

Question 24

u-2 receptor effects

Answer 24

respiratory depression, addiction, constipation and decreased GI motility, increase CSF (cerebral edema)

Question 25

k receptor effects

Answer 25

dysphoria, low abuse, miosis, and diuresis

Question 26

delta receptor effects

Answer 26

respiratory depression, physical dependence, constipation

Question 27

opioid antagonists and effects?

Answer 27

nalaxone, naltrexone, nalmefene - increased sympathetic response (tachycardia, dysrythmias - Vfib), hypertension, excitement (dysphoria), and pulmonary edema)

Question 28

what are mixed agonist/antagonists?

Answer 28

stimulate one receptors and block another

Question 29

where do agonist/antagonist opioids work?

Answer 29

kappa and delta receptors

Question 30

side effects of opioids

Answer 30

pruritis, respiratory depression, N/V, sustained erection, urinary retention, sedation, constipation, and addiction

Question 31

Definition of analgesia

Answer 31

pain relief without loss of conciousness

Question 32

what is morphine 6 glucuronide?

Answer 32

morphine metabolite that has greater duration and analgesic effects than morphine (650x stronger) with lower permeability to BBB

Question 33

How does naloxone work?

Answer 33

reverses respiratory depression with opioid overdose, competative antagonist of all opioid receptors, and can produce opioid withdrawal in abusers (seizures)

Question 34

What is an antagonist?

Answer 34

bind to opioid receptor (u) but fail to activate receptor - reverse the effects of agonist and precipitate opioid withdrawal

Question 35

Meperidine mechanism of action

Answer 35

u and k receptors

Question 36

meperidine actions

Answer 36

respiratory depression, decrease peripheral resistance (increase CO), increase CSF pressure

Question 37

Nalbuphine and butorphanol

Answer 37

causes psychotic issues and has limited role as analgesic

Question 38

Buprenorphine use

Answer 38

opioid detox and work on u receptor

Question 39

Pentazocine classification

Answer 39

antagonist/agonist

Question 40

pentazocine receptors

Answer 40

``` agonist = k antagonist = u and delta ```

Question 41

pentazocine side effects

Answer 41

respiratory depression, hypertension, increase work of heart, decreased GIT activity, tolerance

Question 42

Tramadol receptor and use

Answer 42

u receptor - pain - less respiratory depression

Question 43

Where do opioid antagonist bind?

Answer 43

u receptors, but fail to activate receptor - reverse the effects of opioids (massive withdrawal)

Question 44

Naloxone

Answer 44

used to reverse respiratory depression with opioid overdose - competitive antagonist of u and k receptors, and will cause opioid withdrawal syndrome in abusers (seizures, and increased SNS)