Pain management Flashcards
What risk is associated with concomitant oxycodone and amitriptyline use? What are the signs of this risk?
Increases the risk of serotonin syndrome
o Confusion, hallucinations, extreme changes in bp, tachycardia, shivering, heavy sweating, nausea, diarrhoea, coma, death
Prescribe the safest analgesia in pts w/ chronic liver disease. Why are other analgesics not safe?
Paracetamol 500mg PO qds
- NSAIDs may further increase bleeding risk on top of already having clotting abnormalities from the liver disease
- Opioids may precipitate hepatic encephalopathy
Which NSAIDs have increased/lower risk of GI toxicity?
- COX-1 inhibitors > COX-2 inhibitors (celocoxib, etoricoxib)
- In terms of COX1/2 inhibitors: Aspirin/ketorolac > ibuprofen
When is ibuprofen not recommended?
High dose ibuprofen (≥2400 mg/day) should be avoided in ischaemic heart disease, peripheral arterial disease, cerebrovascular disease, congestive heart failure (NYHA II-III) and uncontrolled hypertension.
What’s the equivalent dose of 50mg of dihydrocodeine as codeine?
50mg if the dihydrocodeine was po, or 100mg if it was injected
What are the Sx of local anaesthetic toxicity?
o Mild -> tingling around mouth/extremities, metal taste, visual disturbance
o Moderate -> altered consciousness, convulsions
o Potentially fatal -> dysrhythmias, cardiovascular collapse, respiratory distress
What are the common co-codamol doses and what’s the max dose per day?
Codeine(mg)/paracetamol: 8/500, 15/500 or 30/500 po
Max dose dictated by paracetamol = 2 tabs QDS (4g/day)
What route is buprenorphine given?
Transdermal patches
How do you convert from codeine/tramadol to morphine?
Add up total in day and divide by 10 (as it’s 10 times weaker than morphine)
Give 4 examples of weak opiates
Codeine
Dihydrocodeine
Tramadol
Low dose buprenorphine
What’s the dose of po AND iv paracetamol for adults <50kg?
PO: Max 2 g in 24 hours (i.e. 500 mg every 4-6 hours)
IV: 15mg/kg over 15 mins every 4-6hrs, max 60mg/kg in 24 hours (i.e. up to 4 doses)
Give 3 examples of co-analgesics (i.e. paracetamol with something). What’s one thing you need to be wary of when giving these specifically (compared to other analgesics)?
o Co-dydramol: 10/20/30mg dihydrocodeine with 500mg paracetamol
o Co-codamoml: 8/15/30mg codeine with 500mg paracetamol
o Tramacet: 37.5mg tramadol with 325mg paracetamol
o BEWARE of increasing sodium
How much codeine can be given a day? What’s the equivalent in morphine?
120mg/day po == 12mg morhpine
In general, how do you convert dosages between opiate pain reliefs?
- Convert to equivalent daily oral morphine (oramorph)
- 2 ppl (or person + conversion chart) to calculate converted dose
When is oxycodone useful to use? And when not?
eGFR 30-60
But avoid in severe renal impairment!
What are the 2 preparations of morphine? Give 2 examples of each
Immediate release
- Oramorph liquid
- Sevredol tablets
Sustained release (tablets/capsules)
- Zomorph / MSL
- MXL
What pain relief class for muscle pain/spasm? Give an example
Relaxant e.g. diazepam
How do you start someone on morphine?
- ~ start on immediate release oral morphine sulphate
- Start at 2.5-5mg po 4 hourly prn
- If been on max codeine, can start on 10mg po 4 hourly prn instead
- Then convert to modified release twice/day
NB when starting a PCA in an opioid naïve pt, also prescribe naloxone as required in case of respiratory depression
What’s the equivalent dose of 50mg of codeine as dihydrocodeine?
50mg po
or 25mg injected
Describe the steps of the WHO pain ladder
1: non-opioid e.g. paracetamol
2. weak opioid e.g. codeine + non-opioid
3. strong opioid e.g. morphine + non-opioid
+ at any stage: adjuvant analgesia if required e.g. anticonvulsant / antidepressant
What’s 12mg/day morphine converted to oxycodone po? and sc?
12mg oramorph ->
6mg oxycodone po ->
3mg oxycodone sc
What must you advise pts taking opioids (i.e. regards side effects)? How can you combat side effects?
- Constipation -> laxatives
- Drowsiness -> ~ resolves w/in 24-48hrs / lower dose (ILLEGAL TO DRIVE 24hrs after taking / 48hrs after dose change)
- Nausea -> ~ resolves / anti-emetic (cyclizine / metoclopramide)
- Inform of signs of toxicity (confusion, hallucinations)
What are the constituents of epinephrine? How do the constituents alter the effect?
Lidocaine and adrenaline
Adrenaline diminishes local blood flow -> slows rate of absorption -> prolongs anaesthetic effect
What pain relief for diabetic neuropathy?
SNRI e.g. duloxetine
- Carbamazepine off-label
- Possibly capsaicin cream
What pain relief classes for neuropathic pain? Give 2 examples of drugs
TCA e.g. amitripytyline
Anticonvulsant e.g. pregabalin / gabapentin
How do NSAIDs like aspirin increase bleeding risk?
- COX-1 inhibition -> prevents platelet aggregation for ~ 7d (platelet lifespan) -> reduced clotting
- Suppress prostaglandins, which ~ protect GI mucosa -> GI ulceration
- Also damage mucosa in other ways (irritant, impaired barrier function, reduced blood flow, interfere w/ repair)
- Can make pre-existing GI ulcers bleed
When do you consider switching opiate? What measures can you try to avoid switching?
Try antiemetics, laxatives, reducing dose, adding in adjuvants like pregabalin
Switch if persistent confusion, drowsiness, nausea, nightmares, itch, toxicity due to renal impairment (if not fluid responsive), still in pain
1st line drug for trigeminal neuralgia
Carbamazepine
How do you convert morphine to oxycodone?
Oxycodone is stronger than morphine
PO Oramorph -> /2 -> PO Oxycodone -> /2 -> SC Oxycodone
How long can fentanyl patches be left on?
Usually 72 hours
Occasionally 48 hours
When is diclofenac contraindicated?
ischaemic heart disease, peripheral arterial disease, cerebrovascular disease and congestive heart failure (NYHA II-IV)
2 examples of COX-1 inhibitors and 4 examples of non-selective NSAIDs
COX2: celecoxib and etoricoxib
Non-selective (i.e. both COX1 and COX2): diclofenac, ibuprofen, aspirin, naproxen
What’s 80mg/day codeine converted to morphine?
10x weaker
so 8mg morphine
Give 2 examples of local anaesthetics
Lidocaine
Bupivacaine
How much weaker are codeine and tramadol than morphine?
10x weaker
i.e. 100mg tramadol = 10mg morphine
Give 3 examples of non-pharmacological methods of treating pain
Acupuncture, physio, psychological therapy, pain management programmes, self-management tools, transcutaneous electrical nerve stimulation (TENS)
When is buccal/sublingual fentanyl useful? How long does it take to have effect?
- Incident pain i.e. predictable pain (e.g. painful ulcer going to be dressed / bony mets give you pain on walking)
- You can give it 20mins before e.g. the ulcer is dressed
How is local anaesthetic toxicity managed?
Stop ongoing LA infusions
Resuscitate through ABCDE (Maintain oxygenation, stop convulsions, support circulation)
Cardiopulmonary resuscitation if cardiovascular collapse
Intralipid infusion used sometimes by anaesthetists
How does clopidogrel increase bleeding risk?
- Irreversibly inhibit platelet aggregation -> reduced clotting
How long does it take for paracetamol to reach peak concentration?
30-60 mins
How long do fentanyl patches take to have effect? What do you need to do in the meantime?
- About 24hrs
- Continue other opioids 8-12hrs after starting patch, until patch starts working
What are the 3 main classes of adjuvants for pain relief? Give 2 examples of each
Antidepressants
- TCAs like amitriptyline
- SNRIs like duloxetine
Anticonvulsants
- Carbamazepine, gabapentin, pregabalin, lamotrigine
NMDA-receptor anatagonists
- Amantadine, ketamine, magnesium, methadone
What are the doses that oramorph comes in?
Available as:
- 10mg/5mls
- concentrated: 20mg/1ml
How can morphine be given if unable to swallow? How do you convert the dose from oral morphine?
Parenteral morphine
- SC morphine sulphate injection (NB IM is painful)
- Can set this up as an infusion (CSCI (continuous SC infusion))
- Half the daily dose given over 24 hrs
Also:
- fentanyl patches
- buccal/sublingual fentanyl
- parenteral sc diamorphine (divide morphine dose by 3)
- parenteral sc alfentanil (BEWARE 30x stronger than morphine)
Which pain meds should be avoided in severe renal impairment and why? Which are ok to use?
Avoid:
- Build up of toxic metabolites
- Codeine and Oxycodone
- Modified release preparations bc will have much longer T1/2 bc of renal impairment so increased risk of overdose
Ok to use:
- Oxycodone if eGFR 30-60
- Fentanyl / butrans patch
- Parenteral alfentanil
Who needs a different to “normal” dose of paracetamol? What measures can be used to try avoid errors?
- Neonates and children; prescribe in mg not ml in hospital, be exact about dose and volume to parents, use dosing table for IV administration and only use the 50ml vials
- <50kg
- Active liver disease / heavy alcohol intake
- IV administration
List 4 advantages of tramadol
When NSAIDs contraindicated
Chronic / neuropathic pain
Causes less respiratory depression
Less constipating
Signs of opioid toxicity
Sedation Confusion Hallucinations Myoclonic jerks Pinpoint pupils Coma
Respiratory depression if taken an overdose
Give 3 risk factors which need to be considered when giving epidural analgesia
impaired coagulation, infection, compromised immunity, cardiovascular instability
Main differences of risks between COX-1 and COX-2 inhibitors?
- COX-1: More GI toxicity
- COX-2: Lower risk of GI toxicity with short-term use (although not absolutely no risk)
- COX-2i and “traditional” NSAIDs (like aspirin/ibuprofen) have increased risk of cardiovascular events
When would you consider giving a PPI in addition to an NSAID?
o Older adults, previous peptic ulcer disease/GI complaints
o Concomitant SSRIs, steroids
o Long term NSAIDs
What route can codeine be given? What route should it not be given and why?
PO or IM
NOT IV bc of anaphylaxis risk
Give 3 uses for acupuncture recommended by NICE
o Frozen shoulder, lower back pain, tennis elbow, osteoarthritis
o Headache, migraine
o Peripheral neuropathies, sciatica, trigeminal neuralgia
o Peripheral vascular disease
How do you convert from codeine to dihydrocodeine?
Same strength po
Injected dihydrocodeine is twice as strong, so divide codeine dose by 2
When are fentanyl patches useful?
- Stable pain ONLY
- Poor oral absorption e.g. bowel obstruction (metastatic ovarian Ca), head/neck Ca
- If difficulty with constipation on morphine
What programme is used in treating pain? Very, very briefly describe it
Pain management programmes (PMP)
group-based rehabilitation to patients with chronic pain, ~ cbt
What pain relief class for bone pain?
NSAID +/ opiate +/ bisphosphonate +/ calcitonin
What’s the common dose of tramadol? How much morphine is this? How much can be given/day?
50-100mg QDS po
i.e. 5-10mg morphine
Max 400mg/24hrs i.e. 100mg QDS i.e. 40mg morphine/day
Give 5 methods to help decrease risk of dependence and addiction to opioids
o Discuss risks of prolonged use with pt (dependence, addiction, tolerance, fatal overdose)
o Develop tx plan, including when tx will end, before starting
o Provide regular monitoring
o Taper dosage slowly when stopping to reduce risk of withdrawal
o Sign-post pts to resources like Patient Information Leaflet
When do you uptitrate morphine and by how much?
- After 24hrs can consider increasing by 1/3-1/2 if pain not 90% relieved
- Can add breakthrough doses to total/day if >2 breakthrough doses/day
Give 4 examples of strong opiates
Morphine Diamorphine Hydromorphone Fentanyl Oxycodone Alfentanil High dose buprenorphine Methadone
What are some relative / absolute contraindications to NSAIDs in general? Briefly explain why
o AVOID if on warfarin or other anticoagulants (bleeding risk)
o May worsen asthma
o AVOID in severe liver disease (bleeding risk, fluid retention, renal blood flow reliant on prostacyclins (which are reduced by NSAIDs)
o Avoid or use with caution in compromised renal function
3 contraindications to codeine
o Severe renal impairment bc of risk of build up of toxic metabolites
o NOT recommended <12yo bc of overdose risk in fast metabolisers (CYP450 -> different analgesic response depending on fast or slow metabolisers)
o NOT for <18yo for tonsillectomy, adenoidectomy or sleep apnoea
Normal dose of aspirin for pain relief?
PO: 300-900mg every 4-6 hours, max 4g/24hrs
What pain relief class for nerve compression and increased oedema/ICP?
Steroid
Give 3 contraindications to using TENS
Over pregnant uterus
At anterior aspect of neck (carotid sinus)
Over allodynic, insensate or broken skin
Older demand pacemaker
Epilepsy or heart rhythm disorder (speak to doctor first)
What’s the normal dose and max dose of oral and IV paracetamol if >50kg?
4 g (or 8 X 500 mg tablets) in a 24 hour period Dosing should not exceed four times a day (4g), leaving at least 4‒6 hours between each dose
Same IV, give over 15mins
Risk specific to aspirin?
AVOID aspirin if <16yo (Reye’s syndrome)
How do you calculate breakthrough dose for morphine? How often can you give this? What’s the best preparation?
- Add up total in 24hrs and divide by 6
- Can be given up to every 4 hours prn for breakthrough pain
- Ideally a fast acting preparation like immediate release morphine sulphate tablets
Give 3 routes local anaesthetic can be given
Epidural block
Peripheral nerve block
Surface anaesthesia (topical)
Give 3 common complications of epidural analgesia
hypotension, respiratory depression, motor block, urinary retention, inadequate analgesia, pruritis
What’s 75mg/day tramadol converted to morphine?
10x weaker
so 7.5mg morphine
List 4 disadvantages of tramadol
Severe n&v
No analgesic effect in some pts
Caution in epilepsy
Non-formulary in some NHS trusts
