Analgesics

Question 1

describe acute / nociceptive pain

Answer 1

short term pain with easily identifiable cause. warning of present damage to tissue

Question 2

describe chronic/ neuropathic pain

Answer 2

pain persists
constant/ intermittent
pain has outlived its purpose

Question 3

describe allodynia pain

Answer 3

pain from stimulus that doesn’t normally cause pain eg. blanket on diabetic foot

Question 4

describe parasthesis pain

Answer 4

painful feelings eg. pins and needles with no apparent stimulus

Question 5

describe the body’s own analgesic system

Answer 5

pain is detected and relayed to brain, brain uses inhibitory pathways stimulated by opiods, serotonin and noradrenaline to secrete local analgesics (opiod, y-aminobutyric acid, encephalins)

Question 6

name the classes of drugs which are used in analgesia

Answer 6

opiods
antidepressants
antiepileptic’s
local anaesthetic

Question 7

what is the mechanism of action of opioids?

Answer 7

blocks pain signals going up to the brain - decreases neurotransmitter release / blocks postsynaptic receptors
enhances body’s own analgesic effect at inhibitory pathways

Question 8

what are the side effects of opioids?

Answer 8

N & V
constipation
drowsiness
resp. depression
hypotension
sedation
dependency

Question 9

what are the cautions /contraindications of opioids?

Answer 9

acute resp. depression
acute alcoholism
head injury

Question 10

what are the interactions with opioids?

Answer 10

alcohol - increased hypotension
MAOI - increased CNS excitation/ inhibition
SSRI/ TCA - increased sedation
carbamazepine - decreased plasma conc. of methadone
cimetidine - inhibit opioids

Question 11

what do opioids mimic?

Answer 11

endogenous ligard “enkephalins” - beta-endorphin, leu-enkeplin, met-enkepalin, dynorphin

Question 12

name the 3 opioid receptor types that opioids agonise and the subtypes

Answer 12

nu, kappa, delta

nu, kappa 1,2,3, delta 1,2

Question 13

which opioid receptor is responsible for most analgesic effects?

Answer 13

nu - CNS, spinal cord, peripheral sensory neurons, GI tract

Question 14

name a pure opioid agonist

Answer 14

morphine - high affinity to nu (low for kappa and sigma)

Question 15

name a mixed opioid agonist

Answer 15

nalorphine - mixed effects on nu receptors

Question 16

name to partial opioid agonists

Answer 16

pentazocine

cyclazocine - (-) effect at nu but partial (+) at sigma and kappa receptors

Question 17

name 2 opioid antagonist and describe when it would be used

Answer 17

naloxone
naltrexone - blocks actions of opioids
used in heroin and morphine overdose

Question 18

name 2 types of antidepressants used as analgesics

Answer 18

serotonin and noradrenaline reuptake inhibitors (SNRI)

selective serotonin reuptake inhibitors (SSRI)

Question 19

describe the mechanism of action of SNRI and SSRI

Answer 19

inhibiting the reuptake of neurotransmitters released naturally in response to pain the effect can be prolonged
mediate descending inhibition of ascending pain pathway

Question 20

what type of pain are SNRI effective in treating?

Answer 20

neuropathic pain (doesn’t work for all)

Question 21

what type of pain are SSRI effective at treating?

Answer 21

diabetic or HIV neuropathy

Question 22

name 2 SNRI

Answer 22

venlafaxine

duloxetine

Question 23

name 2 SSRI

Answer 23

paroxetine

citalopram

Question 24

what type of pain is duloxetine used to treat and what are the side effects?

Answer 24

peripheral neuropathy (esp. diabetic neuropathy)
SE: nausea, somnolence, insomnia, dizziness

Question 25

what type of pain is venlafaxine used to treat and what are the side effects?

Answer 25

diabetic neuropathy | SE: nausea, sedation, headache, dizziness

Question 26

what are the cautions of used SNRI

Answer 26

epilepsy, cardiac disease, diabetes, angle closure glaucoma, pregnancy, b/feeding

Question 27

what do SNRI interact with?

Answer 27

alcohol - increase sedation NSAIDs/ aspirin - increase bleeding tramadol - increase CNS toxicity increased sedation with opoiods

Question 28

why should SSRI not be given with antiepileptic medication?

Answer 28

antagonise effect

Question 29

what is the mechanism of action of antiepileptic's used as analgesics?

Answer 29

inhibit voltage gated Na+ and Ca+ channels inhibit glumate, y-aminobutyric acid (GABA), glycine receptors inhibit action potential firing - prevent nerve transmission limit neuronal excitation - enhance neuronal inhibition

Question 30

name 2 antiepileptic's used as analgesics

Answer 30

carbamazepine | gabapentin

Question 31

what types of pain is carbamazepine used to treat?

Answer 31

glossopharyngeal neuralgia postherpetic neuralgia (nerve damaged caused by varicella zoster virus) trigeminal neuralgia diabetic neuropathies

Question 32

what types of pain is gabapentin used to treat?

Answer 32

``` neuropathic pain: complex regional pain syndrome neuropathy of face postherpetic neuralgia sciatic pain ```

Question 33

what are the side effects of carbamazepine?

Answer 33

``` dizziness diplopsia fatigue nausea hepatotoxicity renal impair ```

Question 34

what cautions are there when using carbamazepine?

Answer 34

renal impairment cardiac disease pregnancy

Question 35

what are the side effects of gabapentin?

Answer 35

anorexia dyspepsia tremor

Question 36

what cautions are there when using gabapentin?

Answer 36

elderly renal failure diabetes pregnancy

Question 37

name 2 local anaesthetics used as analgesics

Answer 37

lidocaine | ketamine

Question 38

what is the mechanism of action of local anaesthetics?

Answer 38

inhibits voltage gated Na+ channels and NMDA receptors - prevent nerve to nerve communication inhibit firing - prevent impulse transmission

Question 39

what type of pain are local anaesthetics useful for treating?

Answer 39

severe intractable pain or crescendo neuropathic pain

Question 40

what is the route of administration and the side effects of lidocaine?

Answer 40

``` IV CNS effects (confusion) depression convulsions hypotension bradycardia ```

Question 41

what are the cautions when using lidocaine?

Answer 41

``` epilepsy hepatic/ resp. impairment atrial fibrillation heart block heart failure ```

Question 42

what is the route of administration and the side effects of ketamine?

Answer 42

``` injectable hypertension tachycardia tremor diplopia myocardial depression ```