Pain and opioids

Question 1

acute vs chronic pain

Answer 1

acute serves a fxn and resolves with Rx of cause. Chronic serves no fxn and persists despite Rx of cause

Question 2

A-delta vs C fibers

Answer 2

fast pain and slow pain (slow is harder to treat)

Question 3

Brief summary of gate control theory

Answer 3

touch fibers can inhibit pain fiber synapses in dorsal horn. Pain fibers can inhibit that inhibition. Brian cans end down descending inhibition of pain fibers

Question 4

mecanism of peripheral sensitization

Answer 4

PGE2 reduces the resting membrane potential so wekers signals cause firing of nociceptors

Question 5

two mechanisms of central sensitization. Significance?

Answer 5

wind up- NMDA receptors greatly amplify signal. PGE2 decreases effect of periaqueductal gray. Both create opioid resistant pain

Question 6

Goal in pain management

Answer 6

4 or less (not 0)

Question 7

Theory behind multimodal analgesia. Examples

Answer 7

work by different mechanisms so you get synergy. Opioid+NSAID, opioid+acetaminophen (vicoden, norco), Nerve block+opioid, cold+NSAID

Question 8

Chronic pain tx with antidepressants: which ones, mechanism, advantages and disadvantages

Answer 8

TCAs and SNRIs (block both 5-HT and NE). Enhance descending inhib system (NOT via rx of depression). Takes wks to see effects. NO TOLERANCE

Question 9

Chronic pain tx with antiepileptic drugs: best in which kind of pain. WHich ones

Answer 9

neuropathic pain. Carbamazepine (first line for trigem neuralgia), gabapentin, pregabalin

Question 10

Do NSAIDs work for neurpathic pain

Answer 10

NO

Question 11

Muscle relaxants for chronic pain: which to avoid

Answer 11

Avoid SOMA (carisoprodol). Metabolized to meprobamate. Get severe withdawal

Question 12

Four major effects of opioids

Answer 12

analgesia, respiratory depression, sedation or euphoria, miosis

Question 13

two opioid effects that dont exhibit tolerance

Answer 13

miosis and constipation

Question 14

opioid withdrawal symptoms

Answer 14

sympathetic overdrive except diarrhea

Question 15

what to give in opioid overdose

Answer 15

naloxone. Mu antagonist

Question 16

morphine metabolites

Answer 16

M3G adn M6G. M6G is 100x more potent than morphine and can enter CNS in renal failure pts.

Question 17

meperidine

Answer 17

metabolizes to normeperedine which can cause seizures in renal failure pts

Question 18

Methadone

Answer 18

T1/2 of 24 hrs. Can result in accumulation

Question 19

Tramadol: mechanism

Answer 19

mu receptro agonism and blocks reuptake of 5-HT and NE

Question 20

three opioid receptors and their fxn

Answer 20

mu-analgesia, euphoria, etc. Kappa- less analgesia but less resp depression. Delta- unknown

Question 21

Relevance of opioid receptors

Answer 21

variable splicing results in pt-pt differences. If side effects but not analgesia= CHANGE the opioid

Question 22

Agonist/antagonist

Answer 22

nalbuphine is kappa agonist, mu antagonist. DONT give to and ADDICT or they get withdrawals