Week 6 Flashcards
Choice of medication
Based on underlying pain mechanisms
* Acute pain: regulated by the opioidergic system
* Persistent pain: associated with a neuropathic component where central sensitisation requires:
– a reduced role of opioids
– an increased contribution of adjuvant/other types of medications
Adjuvant Agents
- Used as supplements to make analgesics more effective,
or - As distinct primary therapy in certain painful conditions.
- May reduce opioid side effects by reducing the dosage used to obtain acceptable pain control.
- May also control symptoms and reduce analgesic requirements.
*Amitriptyline (Tryptanol)
*Carbemazepine (Tegretol)
*Pregabalin (Lyrica)
*Gabapentin (Neurontin)
*Diazepam (Valium)
*Dexamethasone
*Imipramine (Tofranil)
*Phenytoin (Dilantin)
Paracetamol
- Effective analgesic for Mild‐moderate pain
- Oral, IV, PR
- Soft tissue and musculoskeletal origin
Also: - Supplementation of opioids when managing moderate
to severe pain with opioid sparing effect
Evidence for effects on various central mechanisms: - prostaglandin production
- serotonergic, opioid, nitric oxide (NO) & cannabinoid
pathways - probable combination of interrelated pathways
Non‐Steroidal Anti‐Inflammatory Drugs (NSAIDs)
Mild‐to‐moderate pain
* Muscular‐skeletal inflammation and tissue injury e.g.
* Muscular aches
* Tissue sprains
* Osteoarthritis
* Rheumatoid arthritis
* Low back pain
* Headache
NSAIDs non selective
- Ibuprofen (Nurofen - oral)
- Naproxen (Naprosyn - oral)
- Diclofenac (Voltaren - oral)
- Indomethacin (Indocid -
oral/PR) - Ketorolac (Toradol - IM / IV)
NSAIDs cox-2 specific
- Celecoxib
(Celebrex – Oral)
NSAIDs long acting
- Meloxicam (Mobic - Oral)
- Preferential but not Cox 2
Opioids
- Moderate to severe pain: acute or persistent
- Act as agonists at receptor sites in the brain,
spinal cord and other sites outside of the CNS
3 Primary receptors: - mu (μ), delta (δ) and kappa (Ќ)
- Analgesia is mediated mainly via the μ receptor
Opioids types
Morphine: most commonly used, various routes
* Fentanyl: rapid action; strong; various routes
* Oxycodone: oral; used as a step down agent from IV opioids
* Hydromorphone: 5 x potent as morphine; various routes
* Methadone: oral, long action; for persistent pain
* Pethidine: less used, offers no advantage over other opioids
* Codeine: oral with other drugs e.g. paracetamol
* Buprenorphine: SL, IM, SC, TD; long action
Tramadol
- Synthetic, weak mu opioid receptor agonist
- Enhances noradrenergic (40%) and serotonergic (20%)
inhibition - Reduced incidence of respiratory depression
- Lower abuse potential
- Less constipating
- Oral/parenteral
Ketamine
- NMDA antagonist (N‐methyl‐D‐aspartate)
- Dissociative anaesthetic agent
- Ketamine treatment effective for relief of
postoperative pain - For acute and persistent pain
- Often used with an opioid for improved analgesia
& opioid sparing
Cannabis
- Cannabinoid and endocannabinoid systems: special
receptor molecules embedded in the brain and neural
pathways. - The receptors influence the flow of chemical signals to
the brain. - Cannabinoids bind with the endocannabinoid
receptors, suppress signals such as pain, nausea and
depression, boost signals of appetite and euphoria.
Anticonvulsants
Example: Gabapentin or Pregabalin
- Modulates neurotransmitter release by binding to voltage
gated Ca++ channels
- Closes pre-synaptic Ca++ channels
- Diminishes excessive neuronal activity and neurotransmitter
release
- Used for neuropathic pain, post-heretic neuralgia, diabetic
neuropathy, fibromyalgia
Antidepressants
Can exert their analgesic action without any effects on mood
in patients with persistent pain
Lower dose and shorter delay to achieve optimal analgesic
action than required for antidepressant action
Central blockade of serotonin and noradrenaline reuptake
process.
Category includes: tricyclic antidepressants (TCAs),
selective serotonin reuptake inhibitors (SSRI) and serotoninnorepinephrine reuptake inhibitors (SNRIs).
MORNRI: Tapentadol
Mu-opioid receptor agonist (MOR)/noradrenaline
reuptake inhibition(NRI) (MOR-NRI)
Both mechanisms contribute to the analgesic activity
to produce analgesia in a synergistic manner
Relatively moderate activity at the two target sites is
sufficient to produce strong analgesic effects.
Used for both nociceptive and neuropathic pain
Local anaesthetic
Lignocaine
Relieves pain by acting directly on damaged pain fibers under the patch
Reduces aberrant firing of sodium channels.
Lignocaine patches are generally safe and lack systemic side effects.
Effective in PHN, post-stroke pain and complex regional pain syndrome (CRPS)
Capsaicin
Capsaicin is an alkylamide found in capsicum
Selectively stimulates primary afferent C fibers.
These C fibers express TRV1, capsaicin receptors that
nonselectively gate cations, including Na+ & Ca++ which
depolarize axons.
Primary mechanism is depletion of substance P:
neuropeptide involved in the transmission of pain signals
Pain relief is not instantaneous: cumulative depletion of
substance P over a period of weeks brings full effect
Balanced analgesia
- Class of medication used should be determined by
the pathology of the pain and effect of Tx - The medication is optimised with dosage and timing:
–Pre‐emptive
–Regular analgesics
–Break through analgesics - Note: treat side‐effects promptly
WHO: Pharma treatment strategy
Underlying cause of pain should be treated whenever
possible
Individualised therapy
Use a systematic approach
- a two or three step strategy
Oral administration in most patients with persistent
medical illness
Regular administration of analgesics (“by the clock”)
combined with a rescue strategy for breakthrough and
intermittent pain
Monitor and evaluate for therapeutic and adverse
effects
Need to prevent/limit unwanted effects
WHO guidelines
non‐pharmacological
non‐opioid medicines
opioid analgesics
co‐analgesics and
adjuvant medicines
rescue doses
routes of administration
efficacy
safety (including risks)
cost effectiveness
limitations
benefits
side effects and their
prevention
Administration modalities
- Oral
- Rectal
- Intermittent IM or SC injection
- Transdermal
- SC infusion
- IV infusion
- Patient Controlled Analgesia (PCA)
- Epidural
- Intrathecal
- Other regional technique
Acute pain
Various modalities
* Patient‐controlled analgesia
* Epidural and intrathecal analgesia
* Other regional analgesic procedures
* Continuous infusions of opioids, local anaesthetics,
ketamine and other drugs
* Limited trajectory: healing process
* An individually tailored approach
Predominantly nociceptive pain:
* Paracetamol/NSAIDs
* Opioids
* Adjuvant drugs
* Non‐pharmacological & psychological intervention
The following groups may have special needs that require particular
attention:
* Children
* Pregnant patients
* Elderly patients
* Aboriginal and cultural groups
* non‐English speaking people
* Patients with cognitive behavioural and/or sensory impairments
Management Plan: Three phases
- Assessment
– History and physical examination +/‐ further investigations - Management
–Discuss pain management options
–Provide information, assurance and advice encouraging
return to normal activity - Review
–Reassess and revise
Consider patient co‐morbidities
- Age
- Renal or liver impairment
- Opioid tolerance
- Substance abuse
- Respiratory compromise
- Insulin dependent diabetes
- Cardiac Disease
Persistent pain treatment
- Pain is often multifactorial, includes both nociceptive
and neuropathic pain - Requires a multimodal approach (MMA): includes
pharmacological and non‐pharmacological therapy - MMA should be based on the underlying mechanisms of
the disease or condition - Like acute pain, individualised approach offers best
opportunity for pain reduction and control
Rationale for multi‐modal medications
Target multiple mechanisms of pain conditions, addressing both
nociceptive and neuropathic components of pain
* Two or more agents can be used in lower doses, reduces risk of
treatment‐related side effects
* Opioids:
– potent analgesic activity against nociceptive components of pain
– less effective against neuropathic pain
* Antidepressants
– Offer activity against neuropathic pain components
Tailoring treatment
Patient involvement
Regular assessments of adequacy of analgesia
Any adverse effects noted/documented
Re-assessment of pain & effect of intervention
Trial of other interventions if needed
Complementary/Alternative Medicine
- Therapeutic modalities or activities to augment
orthodox approaches (western medicine) - The term alternative therapies infers that they
are outside of traditional medicine - Complementary therapies are becoming more
widely used in health care
Principles of CAM
- The human body‐mind can promote healing
- Energy is crucial to the body to repair itself
- Whole person treatment – health depends upon physical,
personal, social and environmental factors - Illness affects the whole person
- Underlying cause and predisposing factors are important
- Therapies should not cause harm but be supportive
CAM = Person‐centred care
- Seeks to treat the whole person, rather than a
particular disease process - Includes consideration of the person’s social
and environmental factors - Complementary therapies may assist with
provision of holistic approaches to care
Classifications of CAM
Whole medical systems:
– e.g. Traditional Chinese Medicine
* Mind‐body medicine:
– e.g. meditation
* Biologically based practices:
– e.g. herbs, vitamins
* Manipulative and body‐based practices:
– e.g. chiropractic, massage
Acupuncture
- Ancient Chinese medical procedure involving insertion
and manipulation of needles - Believed to stimulate secretion of endorphins,
serotonin, and noradrenaline in the CNS - Potentially also works by constricting or dilating
blood vessels due to release of vasodilators
such as histamine.
Cognitive Therapies
The aim of the therapy is
* To alter
a person’s belief system and modify
undesirable behaviour patterns and perceptions
* To encourage the formation of behaviours and
attitudes that are well adapted and productive in order
that problems can be eliminated
CBT
- A psychological technique that can be taught to patients to reframe thoughts and change the pattern of
thinking: - Identify negative thoughts and then change them
- Studies of CBT for distress and pain in patients with breast cancer have shown significant improvements in these symptoms
- CBT interventions are usually aimed at reducing the distress or threat value of pain
- Enhancing a patient’s sense of their own ability to cope with pain.
- Coping usually refers to acceptance of pain rather than pain control or relief.
CBT requirements
- Define specific and concrete goals for functional activities and moods
- Identify steps towards achieving desired goals
- Consistently reinforce efforts towards goal achievement
- Actively involve the patient in:
– selecting their goals and monitoring progress
– identifying and modifying unhelpful patterns of thought and behaviour
Hypnosis
Creates a trancelike state that resembles normal sleep
during which perception and memory are altered
Results in increased responsiveness to suggestion.
For example, may be used for
* burns dressings
* assistance with childbirth pain
* preparation of patients for surgery
Nutrition
- Protein required
– Specific amino acids for neurotransmitters
– tissue building and maintenance, e.g. muscles - Reduce sugar and starchy carbohydrates
- May need to review certain foods e.g. arthritis and
nightshade family, such as eggplant, capsicums - Opioids and constipation: increase fibre & hydration
- Vitamin D: muscle weakness
Herbal/other medicines
- Neuropathic pain
- Capsaicin
- Rheumatoid Arthritis
- Gamma linolenic acid (GLA): evening primrose oil
- Osteoarthritis
- Fish oils/Krill oil
Massage Therapy
- Touch is the most instinctive response to pain.
- Used as
a form of therapy for thousands of years - A systematic, therapeutic stroking and kneading of the
soft tissues of the body.
Modalities vary: - Some focus on the physical effects that the massage
techniques have on the body - Others focus attention on the flow of ‘energy’ within
the body
Massage
- Stimulation of the body surface can have a corresponding
effect on various organs and systems:
– relaxation of voluntary muscles
– sedation of nerve sensors
– improved blood circulation to the area - Endorphins are also released
– Help to counter the sensation of pain
– Give a feeling of well‐being and relaxation
Meditation/mindfulness
Principle: if you can calm and focus your mind and body, you
may be able to control your pain and degree of feeling
Major study:
* USA:
8 week program for chronic pain showed moderate to
great improvement over long term:
> four years
* “mindfulness meditation training significantly reduce[d] pain
unpleasantness by 57% and pain intensity ratings by 40%
when compared to rest” (Zeidan et al., 2011).
Music therapy
- The use of certain music to divert attention from pain
and to promote a sense of relaxation and well‐being. - Evidence:
- reduced pain intensity and opioid requirements in
the peri‐operative period/after surgery - anxiety and pain reduced in children undergoing
medical and dental procedures
Spinal and joint manipulation
Includes massage, stretching and joint manipulation
Used by:
* Chiropractors
* Osteopaths
* Physiotherapists
* Used to treat a range of musculoskeletal problems
* E.g. low back pain
Transcutaneous Electrical Nerve Stimulation
- Electrical stimuli on the skin preferentially activate low‐
threshold, myelinated nerve fibres - Inhibits nociception by blocking transmission along
fibres to the dorsal horn - low back pain
- arthritic pain
- visceral pain/postsurgical pain
- Delivery/labour pain
Yoga
- Ancient practice using physical postures to obtain
harmony of mind, body and spirit - Shifts balance of the autonomic nervous system from
the sympathetic to parasympathetic response - Strengthen weak muscles and increase flexibility
- Improve oxygenation to body tissue
- Help support the musculoskeletal system
- Regular practice may bring about benefits, including:
- increased oxygenation of the blood
- muscle toning throughout the body
- a clearer and more relaxed mind
- improved posture
- improved circulation of blood and lymph
- regulation of bodily functions
Acute pain: PQRST/OPQRSTUV
- P = Provocation/Palliation
- Q = Quality/Quantity
- R = Region/Radiation
- S = Severity Scale
- T = Timing
- O = Onset
- P = Provocation/Palliation
- Q = Quality
- R = Region/Radiation
- S = Severity Scale
- T = Treatment
- U = Understanding impact
- V = Values
Other pain tools
- Behavioural Pain assessment scale
- Functional assessment: The Physical Functional Ability
Questionnaire - Pain Catastrophising scale
- PASS: pain anxiety symptom scale
- DN4: neuropathic/nociceptive discrimination
- Chronic pain grade: pain activity questionnaire
