Modern Arsenal of Pain Control

Question 1

Descending Inhibitory Pathways (Norepinephrine, serotonin,
endorphines

Answer 1

• NE & S are pain mediators - inhibit pain signals from reaching the higher levels of brain
• Part of the modulatory system in the SC & brain
• Drug classes:
• Antidepressants: TCAs, SSRIs, SNRIs
• Alpha adrenergic agonists
• Opioids (esp Tramadol)

Question 2

Descending Inhibitory Pathways

Tricyclic Antidepressants (TCAs):

Answer 2

• Increases serotonin &/or NE in synapse by inhibiting reuptake
• Take 1-3 weeks for pain control so used for chronic pain
• May have anticholinergic effects
• More effective for conditions like diabetic neuropathy than other anti-depressants
• Nortripyline & Amitriptyline

Question 3

Descending Inhibitory Pathways

Selective serotonin reuptake inhibitors (SSRI):

Answer 3

• Specific inhibitor of S reuptake
• SE (*are much lesser when given for pain): suicidality, impaired platelet aggregation, CNS depression, QT prolongation, serotonin syndrome, SIADH/hyponatremia, sexual dysfunction
• Paroxetine (Paxil), Fluoxetine (Prozac), Sertraline (Zoloft)

Question 4

Descending Inhibitory Pathways

Serotonin and Norepinephrine reuptake inhibitors (SNRI):

Answer 4

• Potent inhibitor of neuronal serotonin & NE repuptake & weak dopamine reuptake
• SE: SUICIDALITY, impaired platelet aggregation, CNS depression, hypercholesterolemia, HTN, SEROTONIN SYNDROME, sexual dysfunction, SIADH/hyponatremia, QT prolongation

Venlafaxine
- Neuropathic pain, DM neuropathy:, onset 1-2 wks, max 6 wks
- Common adverse reactions: nausea, dizziness, drowsiness,

Question 5

Descending Inhibitory Pathways

Alpha adrenergic agonists

Answer 5

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Question 6

Peripheral Sensitization (Sodium Channels on nerves)

Answer 6

Neuropathic pain triggered by spontaneous peripheral nerve activity mediated by sodium channels.
- Cause incl. local tissue injury, ischemia, etc. releasing inflammatory factors, thereby increasing Na channels leading to excitability of the nerves

Question 7

Medication classes dampening this include:

Answer 7

• CBZ: Carbamazepine
• TCAs: Tricyclic antidepressants
• TPM: Topiramate
• Lidocaine

Question 8

Carbamazepine

Answer 8

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Question 9

Topiramate

Answer 9

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Question 10

Lidocaine

Answer 10

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