pain in practice (Andrew) Flashcards
observational changes with pain
- autonomic changes (pallor, sweating, altered breathing, hypertension)
- facial expressions
- body movements
- verbalisations/vocalisations
- interpersonal interactions
- changes in activity patterns
- mental status changes
acute vs chronic pain
acute - from injury or post-operative flare
chronic - nociceptive, neiropathic, visceral, mixed
causes of nociceptive pain
OA
RA
causes of neuropathic pain
central
- post stroke
- MS
- spinal cord injury
- migraine
peripheral
- diabetic neuropathy
- post herpetic nerualgia
types of visceral pain
internal organs
pancreatitis
IBD
types of mixed pain
lower back
cancer
fibromyalgia
considerations for treatment of pain
- type of pain
- cause of pain
- acute or chronic
- exacerbating/relieving factors
- non-pharmacological management
WHO analgesic ladder
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
NSAID choice
ibuprofen
naproxen
(non selective COX inhibitors)
coxibs
celecoxib
etoricoxib
-> selective COX2 inhibitors
aspirin MOA
standard NSAID and blocks thromboxane production (anti-platelet)
examples of weak opioids
codeine
dihydrocodeine
tramadol
tramadol MOA and schedule
Sch 3 CD
inhibits NA and serotonin uptake
analgesics under 16 yrs
1st line (>3mths) - paracetamol/ibuprofen monotherapy -> check adherance and dose before increasing
2nd line - paracetamol and ibuprofen together
3rd line - specialist advice
choice of analgesics in adults
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
key points with NSAIDs
- don’t use themunless yuo have to
- if you have to use them, use them carefully
- consider gastroprotection in high risk patients
How to use NSAIDs carefully?
- assess CV/GI/renal risk
- use a safer drug in lowest effective dose for shortest possible time
- med review
gastroprotection for NSAIDs (esp. over 65)
PPIs
double dose H2RAs
misoprostol
dose of codeine
30-60mg every 4hrs
max 240mg in 24hrs
dose of dihydrocodeine
30mg every 4-6hrs
max 240mg in 24hrs
dose of tramadol
50-100mg every 4hrs
max 400mg in 24hrs
When to use lower dose of weak opioids?
elderly
CKD
hypothyroidism
adrenalcorticoid insufficiency
adverse effects of weak opioids
- 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
s/e of tramadol
seizures hallucinations confusion hyponatraemia hypoglycaemia
interactions with weak opioids
- caution with other CNS depressants/alcohol
- MAOI (avoid during and 2 weeks after stopping)
- tramadol
tramadol interactions
- drugs that lower seizure thershold (TCA, carbamazepine)
- warfarin (raised INR)
- SSRIs (serotonin syndrome, inc seizure risk)
strong opioids (1st line)
morphine oral
- IR liquid/tabs
- MR (OD/BD)
morphine (parenteral)
diamorphine (parenteral)
forms of morphine
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
dose of strong opioid for chronic pain
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
How to convert to MR dose of morphine?
- get total daily dose of morphine
- give same total daily dose but MR product
- calculate appropriate breakthrough dose
How to convert to MR dose of morphine?
- get total daily dose of morphine
- give same total daily dose but MR product
- calculate appropriate breakthrough dose
usual dose in practice when changing to MR morphine
start with 10-20mg MR BD and titrate but continue IR when required
When is breakthrough dose used?
acute flare up of pain/anticipation of increased pain
eg. changing a dressing
breakthrough dose of morphine
1/6th - 1/10th of the total daily dose of morphine
When is morphine given parenterally?
patient unable to swallow
GI dysfunction
How is morphine given parenterally?
IM or SC every 4hrs
IR morphine to SC/IM
give 50% of the dose and same frequency
MR morphine to IM/SC
give 50% of total daily dose
divide and administer every 4hrs
IM/SC dose of IR morphine 60mg MST BD
60mg MST BD = 120mg morphine daily
50% = 60mg
give 10mg IM/SC every 4hrs
diamorphine parenterally
highly soluble opioid
used for high dose SC injections
powder preparation is diluted in small volume of water for injection
adverse effects of strong opioids
- euphoria (initially)
- drowsiness
- n&v (Rx anti-emetics)
- constipation (90% pts, Rx laxatives with strong opioids)
- tolerance
- addiction
- respiratory depression
Why would you give alternatives of strong opioids?
- management of more difficult pain
- side effects (patient tolerability)
- alternative drug preparation (might benefit from patch etc.)
- drug profile (renal impairment, can accumulate)
alternatives of morphine for strong opioids
oxycodone fentanyl patch alfentanil buprenorphine (patch) hydromorphone