2. Chronic Non-Malignant Pain MT1 Flashcards
know the three factors that contribute to an individuals health based on the biopsychosocial model of pain
BIO
1. biology (e.g. pain)
PSYCHO
2. psychology (e.g. mental health treated helps with the pain)
SOCIAL
3. social context (e.g. social determinants of health)
what are the three main types of pain and any subtypes of those
- Acute pain (<30 days)
- subacute pain (1-3 mths)
- Chronic (>3mths)
- nociceptive pain
- neuropathic pain
this is a type of pain caused by damage to the body tissue; it usually feels sharp, aching or throbbing.
nociceptive pain
this type of pain can occur when your nervous system is injured or not working properly; it is often characterized as being a shooting or radiating pain
neuropathic pain
what are some factors that need to be considered when choosing a pain medication for a patient?
- patient choice
- cost, access, insurance coverage
- patient characteristics (age, weight, renal/hepatic function, comorbidities)
- severity/pattern of pain
- type of pain/diagnosis
- response to prior drugs
- therapeutic drug monitoring
- pharmacogenomics (drug receptors, drug metabolism)
know some examples of peripheral vs central neuropathic pain
PERIPHERAL
- carpal tunnel syndrome
- nerve trauma
- phantom limb pain
- peripheral neuropathies (e.g. HIV related, chemotherapy-induced, diabetic neuropathies)
CENTRAL
- central post-stroke pain
- spinal cord injury pain
- brain injury
- multiple sclerosis (MS)
what do “SMART” treatment goals stand for?
S - specific!!!!!
M - measurable
A - action oriented
R - realistic
T - time bound
what are the first line options for management of neuropathic pain
VOLTAGE GATED ALPHA2 LIGAND
gabapentin/pregabalin
SERATONIN-NE REUPTAKE INHIBITORS (SNRI)
duloxetine/venlafaxine
SECONDARY AMINE TRICYCLIC ANTIDEPRESSANTS (TCA)
nortriptyline, amitriptyline)
what are the second line options for management of neuropathic pain?
Tramadol or opioid analgesics
what are the third line options for management of neuropathic pain?
Cannabinoids
If a first line agent for managing neuropathic pain is not quite successful, what are some options that may be considered before trying a second line option?
- switch to another first line agent
- try combining first line agents
what are the three options when combining TCA’s, SNRI’s and gabepntinoids?
- TCA first then add pregabalin
- Pregabalin first then add TCA
- Duloxetine first then add pregabalin
what is the time to effectiveness for an optimal response at any particular dose of an analgesic?
2-4 weeks
When adding agent from another class to help increase analgesia, what should be monitored, especially when combining a TCA & SNRI?
adverse effects!!!!! combining TCA & SNRI can increase risk of serotonin syndrome!
this is a first line agent for managing neuropathic pain; blocks the reuptake of serotonin (5HT) & norepinephrine (NE).
- is useful for concurrent conditions such as insomnia and depression
ADVERSE AFFECTS:
- anticholinergic (dry mouth, constipation, urinary retention in BPH, tachycardia)
- delirium
- orthostatic HYPOtension
- lower seizure threshold
- sexual dysfunction
- QT prolongation and cardiac arrhythmia
e.g. amitriptyline, nortripyline and desipramine
tricyclic antidepressants (TCA’s)
this is a first line agent for managing neuropathic pain; decreases neuronal excitability
ADVERSE EFFECTS:
INCREASED RISK OF OVERDOSE WITH OPIOIDS
- weight gain
- edema
- cns sedation
GABA derivatives
- pregabalin (BID dosing/less CNS side effects)
- gabapentin (TID dosing)
this is a first line agent for managing neuropathic pain; blocks serotonin (5HT) and norepinephrine (NE). useful for concurrent conditions such as anxiety and depression
ADVERSE EFFECTS:
- GI
- sleep disturbance
- CNS drowsiness
- increase BP (at high doses)
e.g. duloxetine and venlafaxine
*duloxetine is also indicated for chronic low back pain and fibromyalgia
SNRI
this is a second line agent for managing neuropathic pain; metabolized by CYP 2D6 to active metabolite
- weak SNRI thus does not work that well for neuropathic pain; risk of serotonin syndrome!!
- weak mu receptor agonist thus risk of addiction, respiratory depression and cns adverse effects
Tramadol
this is the drug of choice for Trigeminal neuralgia (severe facial pain) and is 4th line for chronic pain. it is a strong CYP450 inducer and autoinducer (metabolizes itself - drug works at first then stops working thus need to increase dose).
ADVERSE EFFECTS:
BONE MARROW SUPPRESSION and risk of infections (should get WBC’s checked
- hyponatremia
- hepatitis
carbamazepine
this is a second line option for postherpetic neuralgia (common complication of shingles - burning pain of nerves and skin) and is fourth line for chronic pain. it is a sodium channel blocker. most effective for !!Localized!! neuropathic pain; minimal systemic absorption
supplied as an ung (apply TID-QID prn)
Topical anesthetics (topical lidocaine)
this is a fourth line option for managing neuropathic pain. is used for post-herpetic neuralgia and hand osteoarthritis. it acts by desensitizing pain receptors.
this medication is made from chili peppers therefore wear gloves or wash hands after application.
comes in strengths of 0.025%, 0.05% and 0.075%
AE: local burning, stinging and erythemia
topical capsaicin
this is a third line option for managing chronic neuropathic pain.
AE: dizziness, fatigue, nausea, euphoria, impaired memory, disturbance in attention, psychosis and addiction.
should start with a low dose of a non inhaled option
cannabinoids
cannabinoids are not recommended for those at high risk of major harms including:
- have a history or a high risk of psychosis
- have a history or high risk of substance use disorder
- are pregnant or breastfeeding
- are under the age of 21
what are some options to manage neuropathic pain in pregnant women?
non pharm!!!!!
- acetaminophen
- NSAIDs (ibuprofen/naproxen) avoid in third trimester
- topical lidocaine (limited systemic absorption)
- amitriptyline
- try to avoid opioids, if only option use at lowest dose for shortest period of time due to neonatal withdrawal and rest. depression
what should be the first recommendation when considering therapy for patients with chronic non-cancer pain?
We recommend optimization of non-opioid pharmacotherapy and non-pharmacological therapy first.
what should be the recommendation for patients with chronic non-cancer pain, without current or past substance use disorder and without other active psychiatric disorders, who have persistent problematic pain despite optimized nonopijoid therapy
we suggest ADDING a trial of opioids rather than continued therapy w/o opioids
true/false: opioids are stimulants
false - opioids are depressants
this opioid should be avoided in renal insufficiency
morphine
this opioid is 1.5x as potent as morphine. available in a tamper resistant formulation.
oxycodone
this opioid is 5x as powerful as morphine. available in a tamper resistant formulation
hydromorphone
this combination may minimize constipation and possibly act as an abuse deterrent
oxycodone/naloxone
this opioid is good for the elderly due to less adverse effects; oral formulations are preferred over transdermal for initial trial
buprenorphine
this is a prodrug (SNRI) that is converted to an opioid in a highly variable fashion
tramadol
this is a dried extract from the poppy plant
opium
this is naturally derived directly the opium poppy. examples include morphine and codeine.
opiates
this is a broader class of agents; capable of producing opium-like effects or binding to opioid receptors
opioids
this type of opioid has chemical modification. examples include heroin and oxycodone
semi-synthetic
this type of opioid is a chemical compound capable of binding to an opioid receptor. examples include methadone, meperidine, fentanyl, carfenatil,
synthetic opioids
what are the 3 different opioid receptors
mu, kappa and delta
what are some results (adverse effects/what the drug is supposed to do) when the opioid receptors are activated by an opioid
- pain relief & altered pain perception
- N/V, constipation
- respiratory depression
- cough suppression
- euphoria
- sedation
- miosis (constriction of pupil)
- sweating
what is maximum dose of morphine equivalents that should be prescribed for chronic non cancer pain?
90 mg morphine equivalents daily
what are some of the expectations when starting an opioid?
- ~ 30% reduction in pain
- improved function
- AE tolerable
- prevent addiction
What are the 4 A’s for monitoring opioids?
A - analgesia
A- Activity
A- Aberrant drug behaviour/adherence
A- Adverse effects
this is described as the person needs more and more of the drug too produce the same effect
tolerance
this is described as the endogenous opioid system activity is reduced to the point that the body becomes reliant on continued exogenous opioids
depends
once a person is dependant on opioids, they will experience symptoms of ______ if they stop taking opioids
withdrawal
this is known as the problematic use of a substance. it can range from mild (feeling hungover, being late for work) to severe (homelessness, disease)
addiction
this should be done if a patient is having persistent problematic pain and/or adverse effects to an opioid
rotate to a different opioid
when should opioid tapering/switching be considered?
- lack of improvement in pain and/or function
- non adherence to the treatment plan
- opioid related complications (e.g. overdose, fall, or harm risk, hyperalgesia, adverse effects)
- signs of substance misuse
- patient request
this is an increased sensitivity to pain; worsening pain despite dose increases.
hyperalgesia
what is the general rule for tapering an opioid?
decrease dose by 5-10% every 2-4 weeks
what is the general rule for switching between opioids?
decrease dose by 25-50% depending on the potency of the opioid, concomitant conditions/medications
when tapering a patients opioid, should you taper the SR or IR formulation first?
- this is usually patient preference
- ideally you would want to taper the SR first so the patient still has a good strength of IR in case they experience any withdrawal symptoms while tapering the SR
this is known as chronic widespread pain, increased tenderness, unrefreshing sleep, fatigue, cognitive dysfunction. this condition affects 2-4% of the population and of those affected, 80-90% are women; an increase in sensitivity over time. it is often associated with trauma or adverse life events such as abuse, neglect, bullying, etc.
fibromyalgia
true/false: patients with fibromyalgia are more likely to have other conditions such as PTSD, depression, IBS and low back pain
true
what is the first line for fibromyalgia
NON-PHARM!!
- physical exercise reduces pain
- medication and sleep hygeine
- stress management
- cognitive behaviour therapy
true/false: opioids are effective for fibromyalgia and should be one of the first options considered for treatment
false
this antidepressant improves sleep, reduces pain and fatigue in pts with fibromyalgia
TCA’s
this antidepressant reduces pain (but does not help with sleep, fatigue, QOL) in pts with fibromyalgia
SNRI - duloxetine
this antidepressant has minimal effect on pain and should usually only be considered if the patient has concomitant depression along with fibromyalgia
SSRI
this class of medication is not effective in treating fibromyalgia
NSAIDs
these medications improve pain scores and sleep in pts with fibromyalgia
gabapentinoids
this medication is similar to TCA’s, but may help with sleep in pts with fibromyalgia
cyclobenzaprine (flexiril)
what are some signs of opioid toxicity?
- hypotension
- arrhythmias
- seizures
- acute lung injury
what are the 4 steps for managing an opioid overdose?
- supportive therapy: ABC’s, IV fluids and vasopressors, IV benzodiazepines for seizures
- GI decontamination: activated charcoal if early
- Remove source: consider source (patches, body packing)
- Administer antidote: naloxone
this has a stronger affinity to the opioid receptors than the opioid so it knocks the opioids off the receptors for a short time; reverses respiratory and CNS depression and hypotension
naloxone
approximately how long does naloxone reverse an opioid overdose for?
~ 30 MINS
true/false: you only give one dose of naloxone when a person overdoses
false - give a dose of naloxone and then if the patient is still not breathing after 2-3 minutes give another dose. may have to repeat for the third time
what are some harm reduction measures that can be implemented when a patient is on an opioid?
- limit amount of opioid dispenses (max q month)
- watch for aberrant drug-related behaviours
- monitor for signs/symptoms of toxicity
- careful during dose initiation, titration and switching
- watch for risk factors: sleep apnea, renal dysfunction, older age
- consider tamper resistant formulations
- provide naloxone
- fentanyl patch exchange
list some aberrant drug-related behaviours indicative of opioid misuse
- altering route of delivery (crushing, biting, injecting)
- accessing opioids from other sources
- drug seeking (early refills)
- accompanying addictions
- repeated withdrawal symptoms
- social features (deteriorating or poor social function, concern expressed by family members)
