Modern Arsenal of Pain Control

Question 1

What do norepinephrine and serotonin do?

Answer 1

Inhibit pain signals from reaching the higher levels of brain

Question 2

How do tricyclic antidepressants (TCAs) work?

Answer 2

Increases serotonin and or norepinephrine in the synapse by inhibiting reuptake
May have anticholinergic effects

Question 3

How long does it take for TCAs to begin working?

Answer 3

1-3 weeks for pain control so used for chronic pain

Question 4

What are some examples of TCAs?

Answer 4

Notriptyline and Amitriptyline

Question 5

What are TCAs more effective for treatment of?

Answer 5

Diabetic neuropathy, moreso than other antidepressants

Question 6

How do selective serotonin reuptake inhibitors (SSRIs) work?

Answer 6

Specific inhibitors of serotonin reuptake

Question 7

What are some examples of SSRIs?

Answer 7

Paroxetine (Paxil), Fluoxetine (Prozac), Sertraline (Zoloft)

Question 8

What are some side effects of SSRIs?

Answer 8

Suicidality, impaired platelet aggregation, CNS depression, QT prolongation, serotonin syndrome, hyponatremia, sexual dysfunction

Question 9

How do serotonin and norepinephrine reuptake inhibitors (SNRIs) work?

Answer 9

Potent inhibitor of neuronal serotonin and norepinephrine reuptake and weak dopamine reuptake

Question 10

What are some side effects of SNRIs?

Answer 10

Suicidality, serotonin syndrome, rest are same as SSRIs

Question 11

What are some examples of SNRIs?

Answer 11

Venlafaxine (effexor), duloxetine (cymbalta)

Question 12

What is venlafaxine used for?

Answer 12

Neuropathic pain, diabetic neuropathy

Onset 1-2 weeks, max 6 weeks

Question 13

What are some adverse reactions from venlafaxine?

Answer 13

Nausea, dizziness, drowsiness, hyperhidrosis, hypertension

Question 14

What is duloxetine used for?

Answer 14

Diabetic neuropathy, fibromyalgia, chronic MSK pain

60-120 mg daily

Question 15

What are some adverse reactions of duloxetine?

Answer 15

Sedation, nausea, constipation, ataxia, dry mouth

Question 16

How do alpha adrenergic agonist work?

Answer 16

Stimulates alpha adrenoreceptors in the brainstem, activating inhibitory neuron, reducing the sympathetic outflow of CNS (prevents pain signal transmission)

Question 17

What are some examples of alpha adrenergic agonists?

Answer 17

Clonidine (last line of treatment)

Tizanidine

Question 18

What is clonidine used for?

Answer 18

Neuropathic pain that is not responding to other treatment

Unlabelled: Heroin or nicotine withdrawal, dysmenorrhea, menopausal vasomotor symptoms, migraine prophylaxis

Question 19

What are some adverse effects of clonidine?

Answer 19

Bradycardia, CNS and respiratory depression, hypotension

Question 20

What is tizanidine used for?

Answer 20

Tension-type headache, back pain, neuropathic pain and myofascial pains
Less likely to cause hypotension than clonidine

Question 21

What is peripheral sensitivity?

Answer 21

Neuropathic pain triggered by spontaneous peripheral nerve activity mediated by sodium channels caused by local tissue injury, ischemia releasing inflammatory factors, increasing Na channels

Question 22

What medications are used for peripheral sensitivity?

Answer 22

Carbamazepine, tricyclic antidepressants, topiramate, lidocaine

Question 23

What does carbamazepine do?

Answer 23

An anticonvulsant that limits the influx of sodium ions across the cell membrane

Question 24

What is carbamazepine used for?

Answer 24

Trigeminal or glossopharyngeal neuralgia and neuropathic pain
Monitor drug levels (reach a steady state in 2-5 days)

Question 25

What does topiramate do?

Answer 25

An anticonvulsant that limits the influx of sodium ions and antagonizes glutamate receptors

Question 26

What are some adverse reactions of topiramate?

Answer 26

Dizziness, ataxia, somnolence, psychomotor slowing, paresthesia, weight loss

Question 27

What should be monitored while on topiramate?

Answer 27

Electrolytes and kidney function

Question 28

How does lidocaine work?

Answer 28

Topical application reduces discharge of small afferent nerve fibres by blocking voltage-gated sodium channels (decrease membrane permeability) Gel or patch (will only work in area applied, max 3 patches to area every 24 hours)

Question 29

What is lidocaine used for?

Answer 29

Post-herpetic neuralgia or peripheral neuropathies or other etiologies

Question 30

What are some side effects of lidocaine?

Answer 30

Arrythmias, seizures, coma, respiratory depression or death | Patch: Erythema, swelling, burning or discomfort of the application site

Question 31

How does central sensitivity occur (GABA, Ca)?

Answer 31

Occurs in dorsal horn of the spinal cord with the release of excitatory neurotransmitters (glutamate, substance P) and increased calcium transport (spontaneous impulses)

Question 32

Which medications decrease calcium channel activity?

Answer 32

Gabapentin and Pregablin

Question 33

How do gabapentin and pregablin work?

Answer 33

Modulate voltage gated Ca channels by binding alpha2-delta subunit of presynaptic neurons to regulate excitatory neurotransmitters

Question 34

What is gabapentin used for?

Answer 34

Diabetic neuropathy and neuropathic pain

Question 35

What are the adverse reactions of gabapentin and pregablin?

Answer 35

Somnolence, dizziness, peripheral edema

Question 36

What is pregablin used for?

Answer 36

Neuropathic pain/diabetic neuropathy, spinal cord injury neuropathic pain

Question 37

Which medications are NMDA antagonists (decrease nerve impulse)?

Answer 37

Ketamine, dextromethorphan, methadone

Question 38

How does ketamine work?

Answer 38

Decreases central sensitization and modulation by lowering the threshold for nerve transduction and reduces the effects of substance P Also is a dissociative agent that targets the opioid receptor, Na and K channels to reduce pain

Question 39

What are some adverse reactions to ketamine?

Answer 39

Local skin reactions

Question 40

How does dextromethorphan work?

Answer 40

Low affinity uncompetitive NMDA antagonist (high doses needed), also binds opioid receptors Very short half-life

Question 41

What some side effects of dexomethorphan?

Answer 41

Serotonin syndrome (if in combination with other antidepressants), rash, nausea, drowsiness, constipation/diarrhea, confusion, nervousness, closed-eye hallucinations

Question 42

How does methadone work?

Answer 42

Mu and delta opioid agonist that also blocks the NMDA receptor and inhibits the reuptake of norepinephrine

Question 43

What makes methadone better than morphine?

Answer 43

1 mg=10 mg morphine | Less need for opioid escalation, no active metabolites (less side effects), highly lipophilic (high bioavailability)

Question 44

What are some side effects of methadone?

Answer 44

CNS and respiratory depression, QT prolongation, constipation, nausea and vomiting, dizziness and disorientation