Exam 4: PAIN

Question 1

Neuropathic pain

Answer 1

pain caused by a lesion or disease of the somatosensory nervous system; damage to nerves

• increased nerve cell firing
• decreased inhibition of neuronal actvity d/t deafferenation and/or sensitization

Question 2

Steps in noiciceptive pain

Answer 2

1. stimulation
2. transmission
3. perception
4. modulation

Question 3

Myelinated vs. unmyelinated transmission

Answer 3

• myelinated - fast sharp pain
• unmyelinated - dull ache

Question 4

Endogenous analgesic system

Answer 4

The opiate system
* NDMA receptors decrease the effects of opioates therefore, NDMA antags can enhance the actions of endogenous opiates

Question 5

Role of NE and 5-HT neurons in pain

Answer 5

Inhibit pain transmission?

Question 6

Spontaneous pain transmission

Answer 6

• contiuous - burning, throbbing, aching, shooting
• intermittent (episodic, paroxysmal) - shooting, stabbing, or electric shock-like

Question 7

Hyperalgesia

Answer 7

increased pain form a stimulus that normally provokes pain

Question 8

Allodynia

Answer 8

Pain d/t stimulus that does not normally provoke pain

Question 9

Types of neuropathic pain

Answer 9

1. spontaneous transmission (continuous and intermittent)
2. hyperalgesia
3. allodynia

Question 10

Advantages of using TCAs for pain

Answer 10

• has a lot of data supporting use
• QD dosing
• conmittent insomnia and depression treatment

Question 11

Disadvantages of using TCAs for paiin

Answer 11

• delayed onset
• anticholinergic
• cardiotoxic

Question 12

General TCA dosing for pain

Answer 12

• Start: 25mg QHS
• MDD: 150mg/day

Question 13

Advantages of using SNRIs for pain

Answer 13

• duloxetine FDA approved for PDN ad fibromylagia
• conmittant depression treatment
• favorable side effect profile
• milnacipran: can improve fatigue

Question 14

PDN

Answer 14

painful diabetic neuropathy

Question 15

PHN

Answer 15

post-herpetic neuralgia

Question 16

LBP

q

Answer 16

lo back pain

Question 17

Disadvantages of using SNRIs for pain

Answer 17

• Risk of serotonin syndrome with interacting meds
• Duloxetine: CI in hepatic impairment and ESRD (CrCl <30)
• Milnacipran: BID dosing, HTN ADR

Question 18

SNRI dosing for pain

Answer 18

duloxetine
* start: 30mg QD
* MDD: 60mg BID

venlafaxine
* start: 37.5mg QD or BID
* MDD: 225mg TDD

milnacipran
* start: 12.5mg QD
* titrate over 1 week to 50mg BID
* MDD: 100mg BID

Question 19

milacipran MOA

Answer 19

SNRI
* 3:1 NE:serotonin activity
* NMDA receptor binding
* lacks histaminic and muscarinic activity

Question 20

Gabapentinoids MOA

Answer 20

Modulate hyperexcited neurons

Question 21

Advantages of using gabapentin for pain

Answer 21

• low incidence of DDI and ADR
• FDA approved for PHN

Question 22

Disadvantages of using gabapentin for pain

Answer 22

• mild CNS depression
• significant tox

Renally dose adjusted:
* CrCl 30-59 MDD: 700mg BID
* CrCl 15-29 MDD: 700mg QD
* CrCl 15 MDD: 300mg QD
* CrCl <15 MDD: proportinal to CrCl (if CrCl = 7.5 pt gets half of dose for CrCl 15)

Question 23

Gabapentin formulations and dosing frequency

Answer 23

• PO capsule, tab, solution: TID
• PO tab ER: QD with evening meal
• PO enacarbil tab ER: BID

Question 24

Advantages of using pregabalin for pain

Answer 24

• low incidence of DDI and ADR
• conmittant anxiety treatment
• FDA indicated for PDN, PHN, and fibromyalgia

Question 25

Disadvantages of using pregabalin for pain

Answer 25

* DEA schedule V - dependency and euphoria * mild CNS depression * significant tox * renal insufficiency

Question 26

Pregabalin dosing for pain

Answer 26

* start: 150mg TDD taken BID or TID * titrate every 3-7 days * MDD: 600mg TDD

Question 27

Advantages of using tramadol for pain

Answer 27

* less respiratory depression than opiates * lower abuse potential than opiates * treats neuropathic pain: inhibit reuptake of NE and 5-HT in CNS

Question 28

Disadvantages of using tramadol for pain

Answer 28

DDI * CBZ * quinidine * TCA * SSRI ADR * dizziness * GI upset * constipation * seizure risk

Question 29

Tapentadol indication and MOA

Answer 29

neuropathic pain associated with diabetic peripheral neuropathy; DEA schedule II MOA * mu agonist * NE reuptake inhibition * weak anticholinergic effects

Question 30

Tapentadol dosing

Answer 30

Q4-6 hrs available as 50, 75, 100mg

Question 31

Capsaicin MOA for pain

Answer 31

deplete and prevent re-accumulation of substance P in peripheral sensory neurons FDA approved

Question 32

Important counseling points for Qutenza capsaicin patches

Answer 32

* pre-treat with local anesthetic * use up to 4 patches per application * leave patches on for 60 miites * do NOT use more than Q3 mo. * patch strength is 8% (vs. normal OTC which is .025% or .25%

Question 33

Lidocaine indications

Answer 33

PHN and topical anesthesia -> often used off label for pain Quick onset of 5-10 min :)

Question 34

1st line treatment for neuropathic pain

Answer 34

* TCA * SNRI * gabapentinoids * topicals

Question 35

2nd line treatment for neuropathic pain and when do we use 2nd line

Answer 35

exacerbation or inadequate response to first line * tramadol * combo of 1st line therapies

Question 36

3rd line treatment for neuropathic pain and when do we use 3rd line

Answer 36

inadequate use response to 2nd line * specialist referral first! * SSRI/NMDA antag * interventional therapies

Question 37

4th line treatment for neuropathic pain and when do we use 4th line

Answer 37

inadequate response to 3rd line, 6+ months of neuropathic pain * neuromodulation

Question 38

5th line treatment for neuropathic pain and when do we use 5th line

Answer 38

inadequate response to 4th line * 4-6 week trial of low-dose opiates with regular 3 mo. reviews

Question 39

Is all diabetic neuropathy painful?

Answer 39

No

Question 40

Painful diabetic neuropathy mechanism

Answer 40

* damage to peripheral nerves - hyperexcitability, spontaneous nerve impuses * abnormal electrical connections * coupling of sympathetic and afferent neurons and abnormal release of substance P from A fibers * persistent nervve stimulation activates NDMA receptors

Question 41

treatment for painful **diabetic** neuropathy

Answer 41

* gabapentinoids * TCA * SNRI * sodium channel blockers (TEST QUESTION) consider adding capsacin or switching between these classes before moving on to opiates

Question 42

treatment for post-herpetic neuralgia

Answer 42

* TCAs * antiepileptics (gabapentinoids, divalproex) * tramadol * lidocaine (best for focal) * capsaicin * opiates if all is fails

Question 43

fibromyalgia

Answer 43

* enhanced sensitivity to stimuli (heat and cold) * constant dull ache in all 4 quadrants * often accompanied by fatigue and sleep disturbances

Question 44

treatment for fibromyalgia

Answer 44

* CBT where appropriate * duloxetine * pregabalin * tramadol * milnaciprin is FDA approved but not really on guidelines