Chapter 4 - Pain Flashcards
What is the difference between acute and chronic pain?
Acute - less than 12 weeks
Chronic - more than 12 weeks
How is pain managed in children under 16 years?
Paracetamol or ibuprofen
Switch to the other
Alternate between both
How frequently is paracetamol given?
Every 4-6 hours
Maximum 4 doses per day
How frequently is ibuprofen given?
Every 8 hours
Describe the who analgesic ladder
Step 1. Non-opioids
Step 2. Mild opioids
Step 3. Strong opioids
How frequently should analgesics be reviewed in chronic pain?
At least annually
Is paracetamol:
a) antipyretic
b) anti inflammatory
c) analgesic
a and c
What is the maximum recommended paracetamol dose in
a) >50 kg
b) <50 kg
a) 4g
b) 2g
Why is paracetamol preferred over NSAIDs, especially in the elderly?
Less irritating to the stomach
Less CV and GI complications
What is the maximum pack size of paracetamol that can be sold to the public?
32
What is the maximum number of paracetamol tablets/capsules that can be sold to the public?
100
What are the dangers associated with paracetamol overdose?
Hepatocellular necrosis
Renal tubular necrosis (less common)
What single dosage of paracetamol may cause hepatocellular necrosis?
Generally 10g, or 75mg/kg taken in less than 1 hour
Or 5g if risk factors are present
What are the risk factors for paracetamol overdose?
Alcohol dependency Malnutrition Chronic dehydration Body weight <50kg Severe liver disease Increasing age Concomitant use of hepatic enzyme inducers e.g. rifampin, phenytoin
What are the symptoms associated with paracetamol overdose?
Initially nausea and vomiting
Liver related side effects may occur later
How is paracetamol overdose managed?
If above the treatment line, use IV acetylcysteine
How soon should acetylcysteine ideally be given in paracetamol overdose?
Within 8 hours
NSAIDs have a strong anti-inflammatory action?
Ketoprofen
Piroxicam
NSAIDs have a moderate anti-inflammatory action?
Ibuprofen, naproxen
What is the mechanism of action of NSAIDs?
Inhibit COX-1 and COX-2
What is the effect of inhibiting COX-1 enzymes?
GI irritation due to reducing prostaglandin production
Inhibiting platelet aggregation due to reducing the production of thromboxane A2, so increasing the risk of bleeding
Regulates GFR
What is the effect of inhibiting COX-2 enzymes?
Reduces pain
Reduces inflammation
Reduces fever
What is the main advantage of selective NSAIDS over non-selective NSAIDs?
Reduced GI side effects
What is the main disadvantage of selective NSAIDS over non-selective NSAIDs?
Increased cardiovascular side effects
If a patient with CVD risk factors requires and NSAID, what should be given?
Non-selective NSAID + PPI
Give some examples of non-selective NSAIDs
Ibuprofen Naproxen Mefanamic acid Diclofenax Meloxicam
Give some examples of selective NSAIDs
Celecoxib
Etoricoxib
Why should NSAIDs be taken with food?
To reduce gastric irritation
List some side effects of NSAIDs
GI side effects CV side effects Renal impairment Fluid retention Bronchospasm in some patients
Which NSAIDs have the highest risk of GI side effects?
Piroxicam
Ketoprofen
Which NSAIDs have the lowest risk of GI side effects?
Ibuprofen
Etoricoxib
Celecoxib
Which NSAIDs have the highest risk of cardiovascular side effects?
COXIBs
Diclofenac
Ibuprofen daily dose >2.4g
Which NSAIDs have the lowest risk of cardiovascular side effects?
Ibuprofen daily dose <1.2g
Naproxen
List some cautions/contraindications of NSAIDs
Severe heart failure Uncontrolled hypertension Previous GI ulcer Asthma History of NSAID hypersensitivity Renal impairment On an anticoagulant
How do NSAIDs worsen hypertension and heart failure?
Vasoconstriction
Reducing sodium and water excretion
How do NSAIDs cause sodium and water retention?
Block the production of PGE2, which regulates sodium, chloride and water transport in the LoH
At what eGFR do most NSAIDs need to be avoided in?
<30
Should NSAIDs be used in pregnancy?
Avoid unless the benefit outweighs the risk
Why isn’t phenylbutazone often used?
It is associated with serious side effects, especially haematological side effects
When are celecoxib and etoricoxib used?
Both:
Rheumatoid arthritis, osteoarthritis, ankylosing spondylitis
Etoricoxib is also used for acute gout
What are the disadvantages of compound preparations for pain?
They can not be easily titrated
There are more side effects
Why were co-proximal tablets discontinued?
Concerns over safety
Toxic in overdose
Many people were using it to commit suicide
List some CNS depressants
Opioids Sedatives Benzodiazepines Phenothiazines Alcohol
What is the maximum daily dose of codeine?
240mg
What is the minimum age codeine can be given to?
12 years old
When shouldn’t codeine be given in 12-18 year olds
People with breathing difficulties
People who have had tonsillectomy for sleep apnoea
What is the maximum daily dose of dihydrocodeine?
180mg
What is the usual daily dose and maximum daily dose of tramadol?
Usual dose - 50-100mg every 4-6 hours when required
Maximum daily dose - 400mg
What produces more opioid like side effects, codeine or tramadol?
Codeine
What is the interaction between tramadol and SSRIs?
Both increase the risk of serotonin syndrome
Both lower the seizure threshold
What class of drug is tramadol?
Schedule 3 CD
How frequently is immediate release morphine given?
Every 4 hours
How frequently is modified release morphine given?
Every 12 hours
What drug is usually given second line if morphine is not effective or not tolerated?
Oxycodone
Which opioid is only partially reversed by naloxone in overdose?
Buprenorphine
What has a longer duration of action, immediate release morphine, or buprenorphine?
Buprenorphine
What are the advantages of diamorphine over morphine?
May cause less side effects including nausea and hypotension
May be preferred in syringe drivers as it has a greater solubility, so a smaller dose can be administered in the same volume
Which is more sedating, methadone or morphine?
Methadone
Which has a higher tendency to cause nausea, vomiting and constipation, morphine or tapentadol?
Morphine
Why should pentazocaine be avoided after an MI?
In can increase blood pressure and cardiac work
Does pethidine produce short or long lasting analgesia?
Short acting
This makes it useful for labour?
What is the main issue with pethidine?
It is metabolised to norpethidine, which may cause convulsions
When is dependable to opioids not a concern?
In palliative care
What is tolerance?
When a person no longer responds to a drug in the way that they used to
So a higher dose is required to produce the same effect
What is dependance?
When a person feels like they need to take a drug
They may have difficulty controlling its use
They may experience withdrawal symptoms when the dose is reduced or stopped
Can codeine be used in renal impairment?
Caution in mild to severe impairment
Avoid in severe impairment
Can morphine be used in renal impairment?
Yes, but it is not the recommended opioid and an alternative should be used
Why is morphine not recommended in renal impairment?
It’s active metabolite (MG6) accumulates in renal impairment
MG6 has a greater effect that morphine, so it’s accumulation can result in toxicity and increased side effects
Try to give an alternative that doesn’t accumulate in renal impairment, such as oxycodone, buprenorphine or fentanyl
Why is fentanyl appropriate in renal impairment?
It is metabolised into inactive, non-toxic metabolites
Why is oxycodone appropriate in renal impairment?
It doesn’t accumulate in renal impairment
Why is buprenorphine appropriate in renal impairment?
It is primarily excreted in the bile
How is the pain in sickle cell disease managed?
Paracetamol
NSAIDs
Weak opioids
Strong opioids
Use of an NSAID alongside opioids may potentiate analgesia and allow for lower doses of opioids to be used
What alangesia can be used in dental pain?
Benzydamine
Paracetamol
NSAIDs - don’t give anything that increases bleeding before a dental procedure
What can be used for temporomandibular dysfunction?
Diazepam can be used in the short term
It can help with both the pain and anxiety
Long term, NSAIDs can be used for the pain
What is temporomandibular dysfunction?
When people grind or clench their teeth in the day or night
It can be related to anxiety
And if can cause muscle spasm
How is the pain associated with dysmenorrhea managed?
Oral contraceptive
Paracetamol/NSAID
Antiemetic if needed
Antispasmodic
What is patient controlled analgesia?
When there is a background infusion of analgesic
If needed, a person can increase their analgesic dose up to a predetermined level
Can codeine be used in pregnancy and breastfeeding?
Pregnancy - yes
Breastfeeding - no
Which trimesters can codeine be given in pregnancy?
All in the short term
But if taken near labour, it may cause neonatal respiratory depression
If taken long term it may cause withdrawal symptoms in the baby
What is the paracetamol dose for a 4 month old baby?
60mg every 4-6 hours
Maximum 4 doses daily
What is the paracetamol dose for a 6 year old child?
240-250mg every 4-6 hours
Maximum 4 doses daily
What is the paracetamol dose for an 8 year old child?
360-375mg every 4-6 hours
Maximum 4 doses daily
What is the paracetamol dose for a 16 year old?
0.5-1g every 4-6 hours
Maximum 4 doses daily
What are the cautions of paracetamol?
Body weight under 50kg
Hepatic impairment
Malnutrition
Chronic alcohol consumption
What is the ibuprofen dose for a 9 month old?
50mg three-four times a day
What is the ibuprofen dose for a 2 year old?
100mg three times a day
What is the paracetamol dose for a 6 year old?
150 mg TDS
What is the paracetamol dose for a 13 year old?
300-400mg three-four times a day
Can go up to 600mg four times a day
What dose of ibuprofen should be avoided in heart failure?
Above 2.4g daily
What is used for ibuprofen overdose?
Activated charcoal if >100mg/kg is ingested within the preceding 1 hour
When can naproxen be sold to the public?
For 15-50 year olds
With dysmenorrhea
Maximum 500mg per dose
Maximum 750mg per day
Maximum 3 days
Can sell 9 x 250mg tablets
What should be done if a person is taking celecoxib and fluconazole?
Half the dose of celecoxib
How should diclofenac gel not be used?
Don’t use with bandages
Don’t use of broken skin
Don’t use on mucous membranes
Why isn’t piroxicam used first line?
Risk of serious GI and skin side effects
How is the risk of serious GI and skin side effects of piroxicam reduced?
Only prescribe for OA, RA, and ankylosing spondylitis
Don’t use for general inflammation or pain
Don’t prescribe first line
Co-prescribe a PPI
Maximum 20mg daily
What is the main issue associated with tifaprofenic acid?
Can cause severe cystitis
What important safety information is associated with opioids?
Risk of fatal respiratory depression
Risk of dependance and addiction
What is respiratory depression?
When ventilation isn’t adequate
When is the risk of opioid induced respiratory depression increased?
Opioid naive patients
When opioids are used alongside another CNS depressant
What are the contraindications and cautions of opioids?
Contraindications
Head injury or raised intracranial pressure
Acute respiratory depression
Cautions History of mental heath disorders History of substance misuse Sleep apnoea Asthma Convulsive disorders Hypotension Hypothyroidism
What are the main side effects associated with opioids?
Respiratory depression
Addiction, tolerance, withdrawal
Constipation Nausea and vomiting Sedation Dry mouth Hallucinations Hypotension
What is used for opioid overdose?
Naloxone
List some withdrawal symptoms associated with opioids
Irritability Nausea and vomiting Diarrhoea Muscle aches Shivering Sweating Difficulty sleeping
What classes of drug can cause CNS depression?
Opioids
Benzodiazepines
Barbiturates
Alcohol
What patient counselling should be given with opioids?
Symptoms of tolerance and respiratory depression
Driving may be influenced
It may be an offence to drive if you take too much, even if driving is not impaired
Effects of alcohol are increased
Treatment may not work straight away
What is the minimum licensed age of ibuprofen?
3 months
What is the minimum licensed age of fentanyl?
2 years
What is the minimum licensed age of buprenorphine?
6 years
What is the minimum licensed age of morphine?
1 month
What is the minimum licensed age of tramadol?
12 years
What is the minimum licensed age of oxycodone?
18 years (adult)
What is the minimum licensed age of methadone?
18 years (adult)
Why can’t breastfeeding mothers take codeine?
Approximately 10% of people can’t convert codeine to morphine
Risk of overdose
How long can codeine be used for OTC?
3 days
What important safety information is associated with codeine?
Risk of respiratory depression when used with benzodiazepines
Risk of tolerance, addiction and withdrawal
Contraindications in obstructive sleep apnoea in children I’m who have had a tonsillectomy or adenoidectomy
What are the symptoms of morphine toxicity?
Respiratory depression
Pinpoint pupils
Nausea and vomiting
Can codeine be used in pregnancy?
Yes
But may cause withdrawal symptoms in the neonate if taken during delivery
Why is codeine generally preferred over tramadol?
It is not a CD
It has fewer withdrawal symptoms
Why shouldn’t tramadol be given in epilepsy?
It lowers the seizure threshold
Should patients start on immediate release morphine or modified release morphine?
Immediate release (every 4 hours)
Once the pain is controlled can switch to modified release
How much of the total daily dose of morphine is the breakthrough pain dose?
1/6 to 1/10
What brand is immediate release morphine?
Sevredol
What brand is the 12 hour modified release morphine tablet?
MST
Morphgesic SR
What brand is the 12 hour modified release morphine capsule?
Zomorph
What brand is the 24 hour modified release morphine?
MXL
What classification is morphine?
Schedule 2 CD
If the strength of an oral solution is less than 13mg/5ml, it’s a schedule 5
What are the additional prescription requirements for morphine suppositories?
The morphine salt
If a patient has chronic constipation, is morphine or oxycodone preferred?
Morphine
Oxycodone is contraindicated in chronic constipation
What is the maximum daily oxycodone dose?
400mg
What brand is the immediate release oxycodone?
Shortec
Oxynorm
What brand is the 12 hour modified release oxycodone tablet?
Longtec
Oxylan
What brand is the 24 hour modified release morphine?
Onexilia XL
What are the main risks associated with tapentadol?
Can induce convulsions
Serotonin syndrome
What is the brand name of tapentadol?
Pradexa
Why is methadone good for use in addiction?
It has a long half life
What are the interactions associated with methadone?
Other CNS depressants
Buprenorphine
Bendroflumethiazide (increased risk of hypokalaemia)
Amiodarone (QT interval prolongation)
How of fentanyl used for breakthrough pain?
Use 200mcg buccal tablets
Take one
Take another after 15 mins if required
No more than two tablets per pain episode
If needing more than 4 doses, adjust background analgesia
Why should extremes of body weight be considered with fentanyl?
To avoid overdosing in obese patients
Should use IBW
Are different fentanyl formulations bioequivalent?
No
If switching you need to retitrate the dose
Are all formulations of fentanyl cost effective?
Yes - patch
No - nasal spray, buccal tablet etc
Can fentanyl patches be cut to obtain the right dose?
No - risk of overdose
Why do patients need to avoid heat exposure when using fentanyl patches?
Heat increases the absorption of fentanyl
When switching fentanyl patches, should patients
a) take off the old one then apply the new one
b) apply the new one then take off the old one
a
Should fentanyl patches be used in opioid naive patients?
No - risk of respiratory depression
Which antibiotic interact with fentanyl?
Clarithromycin
It increases the exposure to fentanyl
Adjust the fentanyl dose and monitor
Why may IV fentanyl need to be co-prescribed with a benzodiazepine or smooth muscle relaxant?
IV fentanyl can cause muscle rigidity when the dose is high
How frequently should fentanyl patches be changed?
Every 72 hours
How long may it take for fentanyl patches to work?
24-72 hours
What symptoms of overdose should patients be aware of when using fentanyl?
Breathing difficulties Extreme drowsiness Slurred speech Confusion Dizziness
Can patients with diabetes take buccal fentanyl tablets?
Yes
But they should be aware that each tablet contains 2g of glucose
How is morphine switched to fentanyl patches?
Start fentanyl patch
Continue morphine for 12 hours to ensure that the patient isn’t in pain
How are fentanyl patches switched to morphine?
Stop the fentanyl
Start the morphine at a low dose
Because it takes 17 hours for the fentanyl to reduce by 50%
How long can a women breastfeed after using fentanyl patches?
72 hours
How long can a women breastfeed after using fentanyl buccal tablets?
5 days
What schedhle is fentanyl?
Schedule 2 CD
List some brands of fentanyl
Matrifen Yamex Durogesic DTrans Genito Mezolar Victanyl
Which opioid can only be partially reversed by naloxone?
Buprenorphine
How many buprenorphine patches can be used at a time?
2
But these should be applied in different places
How does buprenorphine interact with other opioids?
It increases the risk of opiate withdrawal
What needs to be monitored when on buprenorphine therapy?
Liver function
Viral hepatitis status should be determined before commencing treatment
When using a 7 day buprenorphine patch, how long should you not apply a different patch to the same area for?
3 weeks
When using a 24 or 72 hour buprenorphine patch, how long should you not apply a different patch to the same area for?
7 days
After taking a buprenorphine sublingual tablet, how long shouldn’t patients eat or drink for?
5 minutes
Are Esperanto and buprenorphine oral lysophillates interchangeable?
No
How do you switch from methadone to buprenorphine?
Reduce methadone to max 30mg daily
If methadone dose is above 10mg, start buprenorphine 4g
If methadone dose is below 10mg, start buprenorphine 2mg
How many days do Butec, BuTrans and Reletrans patches need to be replaced?
Every 7 days
What classification is buprenorphine?
Schedule 3 CD
What are the features of a migraine?
Severe Pulsating Unilateral Precipitated by physical activity May be nausea, vomiting, photophobia, photophonia
What are the two main types of migraine?
Migraine with aura
Migraine without aura
Episodic
Chronic
What is the difference between an episodic and a chronic migraine?
Episodic - a headache that occurs on less than 15 days per month
Chronic - a headache that occurs on more than 15 days per month
And has the characteristics of a migraine on at least 8 of these days
What type of drugs are triptans?
5HT1-receptor agonists
How should triptans be taken for migraine?
Take one tablet as soon as the headache starts
If this helps but the migraine comes back, you can take another tablet after 2 hours
Which NSAID is first line for migraine?
Ibuprofen
When can mefanamic acid be used in migraine?
For menstrual migraines if the woman is already using it for other indications such as dysmenorrhea or menorrhagia
If monotherapy is inadequate for migraines, what’s the next step?
Combined therapy with a triptan and an NSAID
If sumatriptan is inadequate for migraine, what do you use next?
Another triptan
Which antiemetics are used in nausea and vomiting associated with migraine?
Metoclopramide
Prochlorperazine
What options are there for migraine prophylaxis?
First line - propranolol
Alternative beta-blockers - atenolol, metoprolol, bisoprolol
Topiramate
Amitriptyline
How long should a drug for migraine prophylaxis be tried for?
3 months
What is considered a good response to migraine prophylaxis?
A 50% reduction in migraines
What drugs can be used for menstual migraine prophylaxis, and when is it used?
Frovatriptan
Start 2 days before menstruation starts, stop 3 days after menstruation starts
Which triptans are used in cluster headaches?
Sumatriptan, zolmitriptan
Can a patient with diabetes take a triptan?
Yes
But triptans are cautioned in patients with CVD risk factors, including diabetes
Why are triptans contraindicated in cardiovascular disease?
They cause vasoconstriction
Why are triptans unlicensed in the elderly?
They cause vasoconstriction
What are the side effects of triptans?
Nausea, vomiting
Flushing, feeling of heat/cold
Dizziness, drowsiness
Dyspnoea
If a person taking a triptan experiences chest tightness, what should be done?
Discontinue the triptan
This could be due to vasoconstriction
When medications interact with triptans?
MAOI
Drugs that cause serotonin syndrome e.g. SSRI, tramadol, ondansetron, methadone, lithium, buspirone, tapentadol
Which triptan interacts with propranolol which may require a dose reduction?
Rizatriltan
Maximum dose 5mg if the patient is taking propranolol
Take two hours apart
Can people use triptans if they are pregnant or breastfeeding?
Pregnant - only if benefit outweighs risk
Breastfeeding - don’t breastfeed for 12 hours after taking a triptan
What medications are used for the prophylaxis and treatment of cluster headaches?
Prophylaxis - verapamil, lithium
Treatment - sumatriptan injection, or sumatriptan or zolmitriptan nasal spray
What drugs are usually used to manage neuropathic pain?
Amitriptyline
Nortriptyline
Pregabalin
Gabapentin
Do oral medications for neuropathic pain usually work straight away?
No, they usually take 4-6 weeks to work
Is tramadol usually used in neuropathic pain?
No
It should only be used when other treatments have been unsuccessful, whilst on the waiting list to see a specialist
What drug is usually used for trigeminal neuralgia?
Carbamazepine
Why might corticosteroids be useful in neuropathic pain?
They reduce inflammation and swelling, which may take some pressure off of nerves
List some side effects of amitriptyline
Sedation
Anticholinergic side effects
QT interval prolongation, cardiac arrhythmias, severe hypotension
Reduced seizure threshold
What drugs interact with gabapentin and pregabalin?
Alcohol and opioids - risk of respiratory depression
Indigestion remedies - leave a 2 hour gap
What are the maximum doses of pregabalin and gabapentin in neuropathic pain?
Gabapentin - 3.2g
Pregabalin - 600mg
What important safety information is associated with gabapentin and pregabalin?
Risk of respiratory depression
Risk of abuse
Risk of suicidal thoughts and behaviours
Why aren’t capsaicin patches usually used?
They are very expensive (£200 per patch)
How often is capsaicin cream usually applied?
3-4 times a day
Minimum dosage interval 4 hours
What side effects limits the use of capsaicin?
Burning
Avoid having a hot shower or bath before applying the cream as this can make it worse
Don’t use under bandages
Was hands after administration
How should capsaicin be handled?
Cream - wash hands immediately after use
Or what hands 30mins after it has been applied
Patch - use nitrile gloves
