Pain

Question 1

Chronic pain duration definition

Answer 1

More than 3 months

Question 2

Nociceptive pain definition

Answer 2

Caused by inflammatory response to noxious stimuli, not categorical so can overlap with neuropathic

Question 3

Neuropathic pain definition

Answer 3

Initiated/caused by primary lesion or disease in PNS/CNS, not categorical so can overlap with nociceptive

Question 4

What is allodynia

Answer 4

innocuous stimulus now painful

Question 5

NSAID MOA

Answer 5

Ibuprofen, aspirin, naproxen blocks COX non-specifically (so COX-1 and 2) producing prostaglandins which sensitises pain fibres, also anti-inflammatory and anti-pyretic due to PG inhibition

Question 6

NSAID use

Answer 6

Anti-inflammatory, anti-pyretic and analgesic, not used for visceral pain

Question 7

NSAID SE

Answer 7

GI damage

Question 8

Selective COX-2 SE

Answer 8

Celecoxib, etoricoxib, lumiracoxib are associated with increased incidence of MI

Question 9

Paracetamol use

Answer 9

Analgesic when there’s no inflammation, MOA not really known but acts partly by reducing cytoplasmic peroxide tone so only effective when leucocyte infiltration is low

Question 10

Neuropathic pain treatment

Answer 10

Ion channel modifiers e.g. Ca channel blockers (Gabapentin, pregabalin), Na channel blockers (carbamazepine, lignocaine)

Question 11

AMPA receptors in pain

Answer 11

acute touch and pain

Question 12

NMDA receptors effect on pain

Answer 12

rapidly enhance it

Question 13

Ketamine MOA

Answer 13

Blocks NMDA-R, powerful analgesic but has cognitive/memory effects so used in extreme pain

Question 14

Opioid pain relief works on

Answer 14

Mu opioid receptor for endomorphins, delta is similar but no drugs for it

Question 15

Kappa opioid receptor effects

Answer 15

Odd side-effects, maybe gender effects

Question 16

ORL-1 opioid receptor effects

Answer 16

analgesic but can also enhance pain

Question 17

Mu opioid types

Answer 17

Morphine gold standard
Codeine - weaker prodrug for morphine
Fentanyl - fast on/off, often for short surgical procedures
Pethidine - childbirth
Heroin - diacetylmorphine as so prodrug, fast
Naloxone - antagonist for all opioids

Question 18

Opioid MOA

Answer 18

GPCR activated, inhibits N-type Ca channels, opens K channels for hyperpolarisation, inhibitory on pain pathways ascending and descending
Cell body in dorsal root makes opioids which presynaptically inhibit glutamate/substance P release, post synaptically inhibits neuronal activity (a delta and c fibres) so less nociceptor excitation

Question 19

Epidural opioid MOA

Answer 19

Same as normal but just blocks spinal pain pathway, not descending controls so blocks pain below level of epidural

Question 20

Role of emotion in pain

Answer 20

Emotion areas have off cells to reduce pain and on to increase, antidepressants work on NA/5HT descending pain pathways as well as mood

Question 21

Antidepressant use in pain

Answer 21

Helps with neuropathic pain, useful in diabetes

Question 22

Opioid painkillers SE

Answer 22

Sedation
Resp depression (brainstem less sensitive to CO2)
Anti-tussive
Constipation
Nausea/vomiting
Addiction if not used when pain pathways active

Question 23

Opioid painkillers useful SE

Answer 23

Anxiety relief, anti-tussive, constipation

Question 24

Triptans MOA and use

Answer 24

5HT1B/D agonist used for headaches e.g. sumatriptan