Pain and Opioids

Question 1

Fast pain fibers are:

a) Unmyelinated A-delta fibers
b) Myelinated A-delta fibers
c) Unmyelinated C-fibers
d) Myelinated C-fibers

Answer 1

b)Myelinated A-delta fibers

Question 2

Slow pain fibers are:

a) Unmyelinated A-delta fibers
b) Myelinated A-delta fibers
c) Unmyelinated C-fibers
d) Myelinated C-fibers

Answer 2

c) Unmyelinated C-fibers

Question 3

Define Eudynia.

Answer 3

Symptomatic/”Normal” pain

Question 4

Define Maldynia.

Answer 4

“Abnormal” pain-pathophysiologic disease of the nervous system

Question 5

True/False

Chronic pain is protective and usually adequately treated by pharmacological methods.

Answer 5

FALSE

Chronic pain is non-protective (has NO biological use) and is difficult to treat. Chronic pain is a disease.

Question 6

Define Allodynia.

Answer 6

Pain to non-painful stimuli.

Question 7

Define Hyperalgesia.

Answer 7

Heightened pain response to painful stimuli.

Question 8

What 2 substances are released to allow transmission of pain?

Answer 8

Glutamate

Substance P

Question 9

What are the 3 Main Opioid Receptors?

Answer 9

Mu, Delta, and Kappa

Question 10

Name four Endogenous Opioids.

Answer 10

Endomorphins, Endorphins, Enkephalins, Dynorphins

Question 11

True/False

Opioids can cause the release of histamine.

Answer 11

TRUE

Question 12

Morphine

1) Mechanism of Action
2) Onset of Action

Answer 12

1) Classic Mu Opioid receptor Agonist-binds to G-protein coupled opioid receptor to block pain transmission
2) Slow Onset of Action (Low lipid solubility)

Question 13

Does Morphine cross the BBB?

Answer 13

Yes, b/c Morphine is Non-Ionized

Question 14

Does Morphine have an Active Metabolite?

Answer 14

Yes, M-6-Glucuronide (M6G) which is 10x more potent

*Must be careful in Kidney disease d/t kidney excretion

Question 15

Codeine

1)Mechanism of Action

Answer 15

Morphine Derivative
ProDrug that’s converted to Morphine via CYP2D6
*Commonly combined w/Acetaminophen

Question 16

Hydrocodone

1)Mechanism of Action

Answer 16

Morphine Derivative
ProDrug that’s converted to Hydromorphone via CYP2D6
*Commonly combined w/Acetaminophen

Question 17

Hydromorphone

1)Mechanism of Action

Answer 17

Morphine Derivative
5x More potent than Morphine
More lipid soluble=Faster Onset of Action than Morphine

Question 18

Oxycodone

1)Mechanism of Action

Answer 18

Morphine Derivative
ProDrug that’s converted to Oxymorphone via CYP2D6
*Commonly combined w/Acetaminophen
**Oxycontin=Sustained Release formula

Question 19

Methadone

1)Use

Answer 19

Morphine Derivative
Use: Addictive patient’s maintenance and Chronic pain
*ULTRA-LONG half-life

Question 20

Meperidine

1) Mechanism of Action
2) Onset of Action
3) Use
4) Adverse Effects

Answer 20

1) Synthetic Opioid: mu and kappa Opioid Receptor Agonist *1/10th potency of Morphine
2) More lipid Soluble than Morphine=Faster Onset
3) Post-operative Shivering, Pain
4) Psychomimetic effects (d/t kappa action), Histamine release (more than morphine)

Question 21

Why is Meperidine contraindicated to use w/MAOIs and SSRIs?

Answer 21

Serotonin Syndrome: Meperidine inhibits serotonin re-uptake

Symptoms: Delirium, Fever, Convulsions

Question 22

Does Meperidine have an active metabolite?

Answer 22

YES, Normeperidine

Question 23

Fentanyl

1) Mechanism of Action
2) Onset of Action
3) Adverse Effects

Answer 23

1) Synthetic Opioid: Mu receptor agonist
* 50-100x MORE potent than Morphine
2) Short Onset of Action
3) Metabolized by CYPs

Question 24

Alfentanil

1) Mechanism of Action
2) Onset of Action

Answer 24

1) Synthetic Opioid: Mu receptor agonist
* 10x MORE potent than Morphine
2) Extremely Rapid Onset of Action

Question 25

Remifentanil 1) Mechanism of Action 2) Onset of Action 3) Adverse Effects

Answer 25

1) Synthetic Opioid: Mu receptor agonist * Equipotent to Fentanyl 2) Extremely Rapid Onset of Action AND Clearance (3min) * Metabolized by Non-specific Plasma Esterases 3) Little Post-op Pain Relief

Question 26

What does Context Sensitive Half-life mean?

Answer 26

Half-life of the Drug depends on Administration Length of Time (Longer infusion time=Longer Half-life) "Context" is the duration of infusion.

Question 27

``` From the Drugs listed below, which have Context Sensitive Half-lives? Morphine Alfentanil Remifentanil Fentanyl ```

Answer 27

Alfentanil and Fentanyl

Question 28

What is Opioid Synergism?

Answer 28

Opioid + Benzo OR Opioid + Propofol --> causes significantly greater respiratory depression, obtundation, and respiratory arrest at much lower doses of these agents when used together

Question 29

True/False | Spinal Opioids with preservatives are safe to use.

Answer 29

FALSE, Spinal Opioids MUST be Preservative FREE!

Question 30

Tramadol 1) Mechanism of Action 2) Use 3) Adverse Effects

Answer 30

1) Opioid Partial Agonist: binds to mu receptor partially and inhibits re-uptake of monoamines (NE and Serotonin) 2) Mild/Moderate Acute and Chronic Pain 3) Metabolized by CYPs-can cause drug-drug interactions

Question 31

Tapentadol 1) Mechanism of Action 2) Use 3) Adverse Effects

Answer 31

1) Opioid Partial Agonist: binds to mu receptor partially and inhibits re-uptake of monoamines (NE and Serotonin) * Greater mu receptor efficacy than Tramadol 2) Mild/Moderate Acute and Chronic Pain 3) Metabolized by CYPs-can cause drug-drug interactions

Question 32

Nalbuphine 1) Mechanism of Action 2) Use

Answer 32

1) Kappa Opioid receptor agonist AND Partial mu Opioid receptor antagonist * Positive Opioid Benefits w/Fewer side effects 2) Short term, Acute, Moderate/Severe Pain * Does NOT work for Chronic Pain

Question 33

Pentazocine | 1)Mechanism of Action

Answer 33

1) Has 2 Isomers--> One has affinity for kappa Opioid receptor, other does NOT * Has a "ceiling effect"- once max dose reached, NO additional agonists effects occur

Question 34

Buprenorphine 1) Mechanism of Action 2) Use

Answer 34

1) Partial mu Opioid receptor agonist and kappa Opioid receptor antagonist * High affinity for mu receptor=difficult for other Opioids to bind 2) Opioid Addiction (must use high doses)

Question 35

Nalozone 1) Mechanism of Action 2) Use

Answer 35

1) Opioid Antagonism: competitive antagonist at mu, kappa, and delta receptors * Causes REVERSAL of ALL Opioid effects 2) Acute Opioid Overdose * May require multiple dosing d/t half-life of OD drug vs. reversal agent

Question 36

Naltrexone 1) Mechanism of Action 2) Use

Answer 36

1) Opioid Antagonism: competitive antagonist at mu, kappa, and delta receptors * ORAL agent=slower acting 2) Maintenance treatment for Opioid dependence

Question 37

``` Which Opioids below have Active Metabolites? Morphine. Codeine Hydrocodone. Fentanyl Meperidine. Methadone Oxycodone. Oxymorphone Tapentadol. Tramadol ```

Answer 37

``` Morphine Hydrocodone Meperidine Oxycodone Codeine Tramadol ```