Pain

Question 1

difference between hyperalgesia and allodynia?

Answer 1

Hyperalgeisia – a painful stimulus becomes even more painful

Allodynia – a normally not-painful stimulus becomes painful

Question 2

2 reasons for pain hypersensitivity

Answer 2

Inflammatory Pain – caused by inflammatory mediators (ATP, H+, Capsaicin, Prostaglandins) at site of injury

Neuropathic pain – caused by lesion or disease affecting the somatosensory system

Question 3

causes of neuropathic pain?

Answer 3

diabetes, post herpetic neuralgia (VZV), cancer

Question 4

causes of inflammatory pain?

Answer 4

trauma, Sx, arthritis

Question 5

what is peripheral sensitization?

Answer 5

• sensitizes c-fibers and A-delta fibres, lower threshold for activation

Question 6

what is central sensitization?

Answer 6

plasticity of DRG neuron which amplify pain signals from c-fibres and a-delta fibres

Question 7

NSAIDs (aspirin, ibuprofen

Answer 7

COX-inhibitor

Question 8

Morphine

Answer 8

Mu-opioid receptor agonist

Question 9

Gabapentin

Answer 9

Calcium channel blocker

Question 10

Carbamazepine

Answer 10

Sodium channel blocker

Question 11

Ketamine

Answer 11

NMDAR blocker

Question 12

tricyclic antidepressants

Answer 12

NOR/5HT uptake inhibitor – via descending control of pain (locus corelus/raphe nuclei)

Question 13

triptans

Answer 13

5-HT1b/d receptor agonist

Question 14

migraine

Answer 14

triptans

Question 15

inflammatory pain

Answer 15

NSAIDs (aspirin, ibuprofen

Morphine

Question 16

neuropathic pain

Answer 16

Gabapentin
Carbamazepine
Ketamine***
Tricyclic antidepressants

Question 17

what receptor do all opioid drugs act on?

Answer 17

Mu opioid receptor

Question 18

Codeine

Answer 18

Mu opioid partial agonist

Question 19

Fentanyl

Answer 19

ynthetic opioid agonist

Question 20

what is the antidote for opioid overdose?

Answer 20

naloxone

Question 21

what fibres have opioid receptors?

Answer 21

c-fibres and A-delta

Question 22

what sensations are not affected by opioids?

Answer 22

a-beta fibres:

fine and discriminative touch

Question 23

what is the effect of opioids on presynaptic receptors?

Answer 23

on presynaptic opioid receptors (75%) to inhibit release of glutamate and other peptide inflammatory mediators

(via opening K+ channel to reduce Ca2+ influx to reduce NT release),

Question 24

what is the effect of opioid receptors on postsynaptic receptors?

Answer 24

post-synaptic receptors (25%) to inhibit neuronal activity

via opening K+ channel to cause hyperpolarisation

Question 25

what is an example of descending control of pain?

Answer 25

from the periaqueductal grey – enkephalins

Question 26

useful effects of opioids?

Answer 26

Pain relief
Anti-tussive (good for chest Sx or as cough medication)

Relief of anxiety (pre-Sx)

Constipation (good for bowel Sx or as diarrhoea medication)

Question 27

SE of opioids?

Answer 27

constipation
dependance

Sedation
Respiratory depression
Anti-tussive
Nausea and Vomiting