Opioids

Question 1

T/F: Patients will often be able to identify a specific spot for orofacial pain.

Answer 1

False

Not great spatial resolution

Question 2

What fibers will carry the first onset of quick pain?

Answer 2

Myelinated A delta fibers

Question 3

Which fiber responds with dull aching pain?

Answer 3

C fibers (unmyelinated)

Question 4

How does inflammation stimulate nociceptors?

Answer 4

Inflamed tissue releases mediators (prostaglandins, substance P, TNF-a, IL1b, IL-6) which interact with receptors and facilitate pain signals

Question 5

Tissue injury can lead to sensitization of the pain response through which two methods?

Answer 5

Allodynia - response to normally painless stimuli

Hyperalgesia - heightened sense of pain to noxious stimuli

Question 6

In general, how do opioids intervene to diminish pain?

Answer 6

Inhibition at periphery and inhibition of CNS activity

Question 7

T/F: A single neuron in the CNSa might receive input from hundreds of axons.

Answer 7

True

Means a threshold must be reached for the nerve to fire

Question 8

Which channels do you want to activate to hyperpolarize (inactivate) the neuron?

Answer 8

Cl- and K+ channels

Cl- channel will let Cl in the cell
K+ channel will let K+ out of the cell

Question 9

What are the four types of endogenous opioids?

Answer 9

1. Pro-opiomelanocortin peptides (B-endorphin)
2. Pro-enkephalin peptides
3. Prodynorphin peptides (Dyn-A, Dyn-B, a-neo-endorphin
4. Endomorphins

Question 10

What are the three types of opioid receptors?

Answer 10

Mu, kappa, and delta

Mu is the target of most drugs

Question 11

What are the common characteristics of opioid receptors?

Answer 11

Widely distributed in CNS

GPCR

Activate G(alpha)i - inhibit cAMP production

Question 12

___________ is the natural agonist of the mu opioid receptor.

Answer 12

B-endorphin

Question 13

_________ and __________ are the natural agonists of the delta receptor.

Answer 13

Met-enkephalin and leu-enkephalin

Question 14

What are the agonists to the kappa receptor?

Answer 14

Dyn-A, Dyn-B, and a-neo-endorphin

Question 15

T/F: The GPCRs that are activated by opioids are blockers of the nerve pain signal.

Answer 15

False

Make it more difficult for nerve impulses to be conducted

Question 16

What is the pathway for opioid activity?

Answer 16

Activates G(alpha)i -> inhibits adenylate cyclase -> less cAMP -> inhibits PKA -> less Ca entry

Activates G(beta)G(gamma) -> hyperpolarizes the cell

Question 17

T/F: Opioids can inhibit synaptic transmission if receptors are located pre- or post- synaptically.

Answer 17

True

Question 18

T/F: Mu receptors are found in the GI tract.

Answer 18

True

Leads to constipation

Question 19

T/F: Mu receptors are mostly presynaptic.

Answer 19

True

Question 20

What two nerve pathways are affected by opioids?

Answer 20

Inhibit ascending pathway from pain stimuli

Activate descending pathway of pain inhibition

Question 21

How do opioids activate the pain inhibition pathway?

Answer 21

Inhibit GABA

GABA normally hyper-polarizes neurons -> inhibition

We are therefor inhibiting the inhibitor leading to activation

Question 22

What are some common clinical effects of opioids?

Answer 22

Analgesia, Respiratory depression, constipation, GI spasm, physical dependence

Question 23

What is the most serious acute adverse effect of opioids?

Answer 23

Respiratory depression

Question 24

T/F: Morphine produces analgesia without sedation.

Answer 24

True

Question 25

T/F: The active form of morphine is injected into the patient.

Answer 25

False Must be glucuronidized to the active form Most turned to inactive form

Question 26

Where is it suggested that morphine has the greatest effect?

Answer 26

LImbic system

Question 27

How is tolerance first manifested in morphine?

Answer 27

Shortened or diminished analgesia

Question 28

When is tolerance of morphine normally seen?

Answer 28

After 5-7 days of treatment

Question 29

T/F: Morphine-3-glucuronide is the primary and active product of morphine metabolism.

Answer 29

False Primary but inactive

Question 30

Why is morphine not effective taken orally?

Answer 30

Gets metabolized into M-3-G (innactive) more quickly

Question 31

What makes codeine different from morphine?

Answer 31

Substitution at 3 position makes it more effective taken orally

Question 32

T/F: Fentanyl is often given in patches and is much stronger than morphine.

Answer 32

True

Question 33

T/F: Fentanyl is often users for anesthesia.

Answer 33

True

Question 34

What are the two major factors leading to the increased strength of fentanyl?

Answer 34

1. It is more lipid soluble | 2. Binds tighter to the mu receptor

Question 35

T/F: The problem with fentanyl has to do with its therapeutic index.

Answer 35

False

Question 36

Why are fentanyl affects hard to reverse with narcan?

Answer 36

Binds so tightly

Question 37

__________ is an injected opioid antagonist.

Answer 37

Naloxone