pain in practice (Andrew) Flashcards

1
Q

observational changes with pain

A
  • autonomic changes (pallor, sweating, altered breathing, hypertension)
  • facial expressions
  • body movements
  • verbalisations/vocalisations
  • interpersonal interactions
  • changes in activity patterns
  • mental status changes
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2
Q

acute vs chronic pain

A

acute - from injury or post-operative flare

chronic - nociceptive, neiropathic, visceral, mixed

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3
Q

causes of nociceptive pain

A

OA

RA

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4
Q

causes of neuropathic pain

A

central

  • post stroke
  • MS
  • spinal cord injury
  • migraine

peripheral

  • diabetic neuropathy
  • post herpetic nerualgia
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5
Q

types of visceral pain

A

internal organs
pancreatitis
IBD

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6
Q

types of mixed pain

A

lower back
cancer
fibromyalgia

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7
Q

considerations for treatment of pain

A
  • type of pain
  • cause of pain
  • acute or chronic
  • exacerbating/relieving factors
  • non-pharmacological management
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8
Q

WHO analgesic ladder

A

step 1 - paracetamol (non-opioid)

step 2 - codeine (weak opioid), keep the paracetamol

step 3 - morphine (strong opioid), stop the weak opioid

can take NSAIDs at same time

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9
Q

NSAID choice

A

ibuprofen
naproxen
(non selective COX inhibitors)

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10
Q

coxibs

A

celecoxib
etoricoxib
-> selective COX2 inhibitors

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11
Q

aspirin MOA

A

standard NSAID and blocks thromboxane production (anti-platelet)

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12
Q

examples of weak opioids

A

codeine
dihydrocodeine
tramadol

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13
Q

tramadol MOA and schedule

A

Sch 3 CD

inhibits NA and serotonin uptake

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14
Q

analgesics under 16 yrs

A
1st line (>3mths) - paracetamol/ibuprofen monotherapy
-> check adherance and dose before increasing

2nd line - paracetamol and ibuprofen together

3rd line - specialist advice

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15
Q

choice of analgesics in adults

A

1st line

  • paracetamol 1g QDS
  • OR ibuprofen 400mg TDS max 2.4g daily

2nd line
- paracetamol and ibuprofen

3rd line

  • alternative NSAID
  • eg. naproxen 250-500mg BD

4th line

  • weak opioid
  • eg. codeine up to 60mg QDS with paracetamol +/- NSAID

**consider PPI with NSAID

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16
Q

key points with NSAIDs

A
  1. don’t use themunless yuo have to
  2. if you have to use them, use them carefully
  3. consider gastroprotection in high risk patients
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17
Q

How to use NSAIDs carefully?

A
  • assess CV/GI/renal risk
  • use a safer drug in lowest effective dose for shortest possible time
  • med review
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18
Q

gastroprotection for NSAIDs (esp. over 65)

A

PPIs
double dose H2RAs
misoprostol

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19
Q

dose of codeine

A

30-60mg every 4hrs

max 240mg in 24hrs

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20
Q

dose of dihydrocodeine

A

30mg every 4-6hrs

max 240mg in 24hrs

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21
Q

dose of tramadol

A

50-100mg every 4hrs

max 400mg in 24hrs

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22
Q

When to use lower dose of weak opioids?

A

elderly
CKD
hypothyroidism
adrenalcorticoid insufficiency

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23
Q

adverse effects of weak opioids

A
  • CNS depression (sedation, caution driving etc)
  • GI (nausea, vomiting, constipation)
  • dependence/tolerance (max 3 days OTC, caution in suspected dependence/repeat purchases/withdrawal symptoms)
  • tramadol s/e
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24
Q

s/e of tramadol

A
seizures
hallucinations
confusion
hyponatraemia
hypoglycaemia
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25
Q

interactions with weak opioids

A
  • caution with other CNS depressants/alcohol
  • MAOI (avoid during and 2 weeks after stopping)
  • tramadol
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26
Q

tramadol interactions

A
  • drugs that lower seizure thershold (TCA, carbamazepine)
  • warfarin (raised INR)
  • SSRIs (serotonin syndrome, inc seizure risk)
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27
Q

strong opioids (1st line)

A

morphine oral

  • IR liquid/tabs
  • MR (OD/BD)

morphine (parenteral)

diamorphine (parenteral)

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28
Q

forms of morphine

A

IR

  • Oramorph morphine sulphate oral solution (10mg/5ml)
  • Oramorph concentrated morphine sulphate oral solution (20mg/ml)
  • Sevredol tabs (10/20/50mg)

12hr MR

  • MST Continus tabs
  • Zomorph caps

24hr MR
- MXL caps

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29
Q

dose of strong opioid for chronic pain

A

initiation
- 5-10mg every 4hrs of IR morphine adjusted according to response

adjustments
- no more than one third/half of total daily dose ever 24hrs

aim = lowest effective dose based on symptom control and s/e

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30
Q

How to convert to MR dose of morphine?

A
  1. get total daily dose of morphine
  2. give same total daily dose but MR product
  3. calculate appropriate breakthrough dose
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31
Q

How to convert to MR dose of morphine?

A
  1. get total daily dose of morphine
  2. give same total daily dose but MR product
  3. calculate appropriate breakthrough dose
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32
Q

usual dose in practice when changing to MR morphine

A

start with 10-20mg MR BD and titrate but continue IR when required

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33
Q

When is breakthrough dose used?

A

acute flare up of pain/anticipation of increased pain

eg. changing a dressing

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34
Q

breakthrough dose of morphine

A

1/6th - 1/10th of the total daily dose of morphine

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35
Q

When is morphine given parenterally?

A

patient unable to swallow

GI dysfunction

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36
Q

How is morphine given parenterally?

A

IM or SC every 4hrs

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37
Q

IR morphine to SC/IM

A

give 50% of the dose and same frequency

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38
Q

MR morphine to IM/SC

A

give 50% of total daily dose

divide and administer every 4hrs

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39
Q

IM/SC dose of IR morphine 60mg MST BD

A

60mg MST BD = 120mg morphine daily

50% = 60mg

give 10mg IM/SC every 4hrs

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40
Q

diamorphine parenterally

A

highly soluble opioid

used for high dose SC injections

powder preparation is diluted in small volume of water for injection

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41
Q

adverse effects of strong opioids

A
  • euphoria (initially)
  • drowsiness
  • n&v (Rx anti-emetics)
  • constipation (90% pts, Rx laxatives with strong opioids)
  • tolerance
  • addiction
  • respiratory depression
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42
Q

Why would you give alternatives of strong opioids?

A
  • management of more difficult pain
  • side effects (patient tolerability)
  • alternative drug preparation (might benefit from patch etc.)
  • drug profile (renal impairment, can accumulate)
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43
Q

alternatives of morphine for strong opioids

A
oxycodone
fentanyl patch
alfentanil
buprenorphine (patch)
hydromorphone
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44
Q

What is oxycodone?

A

semi-synthetic analogue of morphine

different profile

strong kappa agonist

mu agonist

45
Q

metabolite of oxycodone

A

metabolised to oxymorphone

-> caution in hepatic impairment

46
Q

potency of oxycodone

A

1.5x as potent as morphine

2x as potent SC as oral

47
Q

oxycodone in renal impairment

A

clearance of drug and metabolites is reduced

48
Q

When can oxycodone used?

A

2nd line
difficult pain
MILD renal impairment

49
Q

forms of oxycodone

A

IR caps and liquid

MR tabs

injection

50
Q

What is fentanyl patch?

A

semi-synthetic analogue of morphine
potent mu agonist
highly liphophilic

51
Q

metabolite of fentanyl

A

norfentanyl

52
Q

fentanyl patch and renal impairment

A

safe

53
Q

When can fentanyl patch be used?

A

2nd line
STABLE PAIN
side effects (constipation)
renal impairment

54
Q

caution with fentanyl patch

A

when converting from other opioids and titrating dose

55
Q

How to apply a fentanyl patch?

A
  • non-hairy, non-irritated, non-irradiated skin, flat surface of torso or upper arm
  • skin cleaned with water only, completely dry before applying
  • don’t use cut/divided/damaged patches
  • apply for 72hrs (3 days) then a new one applied to a different site
  • safe disposal
  • patient stay on SAME BRAND
56
Q

How to use fentanyl patch for 1st time?

A
  • wear for 24hrs to see the analgecis effect (gradual inc in plasma fentanyl conc)
  • phase out other analgesia gradually from 1st patch
  • close monitoring of efficacy and s/e
  • dose adjusted at 48-72hr intervals in steps of 12-25mcg/hr if necessary
  • can use more than one at a time (apply at same time)
57
Q

Who should only use fentanyl patches?

A

patient who is stable on morphine

58
Q

morphine equivalent to fentanyl patches

A
morphine 30mg = fentanyl 12 patch
morphine 60mg = fentanyl 25 patch
morphine 120mg = fentanyl 50 patch
morphine 180mg = fentanyl 75 patch
morphine 240mg = fentanyl 100 patch
59
Q

How to convert from morphine to fentanyl patches?

A
  1. calculate daily dose of MR morphine
  2. check equivalence chart
    - > usually 25-50% reduction in dose to ensure safety (lower mcg patch)
  3. calculate appropriate beakthrough dose (as morphine oral solution or oxycodone solution)
60
Q

breakthrough dose foe fentanyl 75mcg patch

A

75mcg = 180mg morphine

1/10th = 18mg
1/6th = 30mg

(20mg PRN appropriate)

61
Q

other forms of fentanyl (specialist Rx)

A

buccal
sublingual
intranasal

62
Q

What is alfentanil?

A

synthetic derivative of fentanyl
more rapid onset
shorter duration of action (less liphophilic)

63
Q

potency of anfeltanil

A

1/4 of fentanyl

10x SC diamorphine

64
Q

alfentanil in renal impairment

A

safe

65
Q

Wehn is anfentanil used?

A

2nd line
renal failure
SC PRN short acting

66
Q

preparation of alfentanil

A

injection

67
Q

What is buprenorpheine?

A

semi-synthetic analogue of morphine
partial mu agonist
kappa antagonist
delta antagonist

68
Q

metabolites of buprenorphine

A

norbuprenorphine

others

69
Q

2 brands of buprenorphine

A

Transtec

BuTrans

70
Q

Transtec potency

A

low dose strong opioid

35mcg = 30-60mg PO morphine

71
Q

BuTrans potency

A

weak opioid

5mcg = 30-60mg PO codeine

72
Q

durations of buprenorphine preparations

A

Transtec 4 days

BuTrans 7 days

73
Q

When is buprenorphine used?

A

2nd line
stable pain
low dose

74
Q

What is hydromorphone?

A

semi-synthetic analogue of morphine

potent mu selective agonist

75
Q

metabolites of hydromorphone

A

H3G

other minor ones

76
Q

potency of hydromorphone

A

7.5x PO morphine
2x as potent as SC as PO
-> SC unlicenced

77
Q

hydromorphone in renal impairment

A

clearance unchanged but metabolites accumulate

78
Q

preparation of hydromorphone

A

capsules

79
Q

When is hydromorphone used?

A

2nd line

mild/moderate renal impairment

80
Q

What can cause neuropathic pain?

A
infection
inflammation
metabolic diseae
trauma
compression
chemical induced nerve damage
81
Q

CNS neuropathic pain (brain/spinal cord)

A

traumatic spinal cord injury
central post stroke pain
pain associated with a degenerative disease

82
Q

PNS neuropathic pain

A

diabetic polyneuropathy (DPN)
postherpetic neuralgia (PHN)
HIV sensory neuropathy
carpal-tunnel syndrome

83
Q

presentation of neuropathic pain

A

burning constant pain
stabbing paroxysmal attacks
signs of hypersensitivity on clinical examination

84
Q

Do opioids and anti-inflammatories work for neuropathic pain?

A

NO

85
Q

consequences of neuropathic pain

A

psychological

reduction in QoL

86
Q

pain ladder for neuropathic pain

A

1st line

  • tricyclic antidepressants
  • OR antiepileptic (only 1 drug)

2nd line
- tricyclic antidepressat and antiepileptic (combination)

3rd line

  • strong opioids (alone or combination with prevoius drugs)
  • +/- invasive procedures

-> implantable pump, dorsal colum stimulator

87
Q

tricyclic antideressant for neuropathic pain

A

amitriptyline

88
Q

How does amitriptyline work?

A

blocks pre-synaptic reuptake of NTs (Sr, NA)

maybe NMDA receptor antagonist

89
Q

How long does it take amitriptyline to work?

A

3-7 days

90
Q

side effects of amitriptyline

A

antimuscarinic

  • dry mouth
  • confusion
  • constipation
91
Q

dose of amitryptyline

A

10mg nocte

up to 75mg nocte

92
Q

alternatice TCAs for neuropathic pain

A

imipramine

nortriptyline

93
Q

antiepileptics used for neuropathic pain

A

gabapentin

pregabalin

94
Q

How do antiepileptics work?

A

chemical analogue of GABA

bind to site in CNS

interact with alpha delta Ca channels in CNS

95
Q

antiepileptics and renal impairment

A

renally excreted

-> caution

96
Q

s/e of antiepileptics

A

drowsy

dizziness

97
Q

pharmacokinetics of gabapentin

A
  • nonlinear and dose dependent profile of absorption
  • higher inter subject variability to the absolute bioavailability
  • slow individual titration

100mg nocte
max 3,6g daily divided doses

98
Q

pharmacokinetics of pregabalin

A
  • linear pharmacokinetic profile
  • 90% bioavailability
  • more predictable
  • onset of pain relief quicker
99
Q

licence for duloxetine

A

diabetic neuropathy

100
Q

How does duloxetine work?

A

selective inhibitor of serotonin and noradrenaline reuptake

101
Q

dose of duloxetine

A

60mg daily

max 120mg

102
Q

What metabolises duloxetine?

A

CYP 450 enzymes

103
Q

s/e fo duloxetine

A
nausea
dry mouth
constipation
insomnia
dizziness
drowsy
104
Q

NICE recommendations for neuropathic pain

A
  • offer choice of amitriptyline, duloxetine, gabapentin or pregabalin
  • try another
  • tramadol for acute rescur therapy only
  • capsaicin cream if oral agent unsuitable
  • carbamazepine for trigeminal neuralgia
105
Q

options for neuropathic pain speaiclist Rx

A

ketamine

methadone

106
Q

other treatment for bone pain in cancer/bone disease

A

bisphosphonates
calcitonin
radiopharmaceuticals

107
Q

other treatments for MSK pains

A

muscle relaxants

benzodiazepines

108
Q

non-drug pain relief

A
heat/cold
massage
TENS
radiotherapy
nerve blocks
acupuncture
psychological therapies