Wk 6: Pain management Flashcards
What types of drugs work on the perception?
- paracetamol
- opoids
- anti depressants
- MORNRI
What types of drugs work on the modulation?
- antidepressants: SNRI, SSRI, TCA
What types of drugs work on transmission?
- opioids
- local anesthetic
What should be considered when deciding on medication to give?
Types of pain
Acute pain: related to opoidergic system
Persistent pain: associated with neuropathic
What types of drugs work for nociceptive pain?
- NSAIDs
- opioids
What types of drugs work for neuropathic pain?
First line:
- antidepressants
- anticonvulsants
- topical agents
What are adjuvant agents?
= medications that aren’t typically used for pain but may be helpful due to their mechanism of action.
- sometimes have have analgesic properties.
- act on substance P and other NTs
Include
- muscle relaxants
- antidepressants
- anticonvulstants
Why might adjuvant agents be used?
- for neuropathic pain
- to supplement other typical pain medication use
- to reduce opooid side effects by reducing the demanded dose needed to reduce pain
- as a primary therapy again pain
- control symptoms and thus again reduce analgesuc requirements
Explain the use of paracetamol
Simple anaglesic and antipyretic
- mild ot moderate pain
- can be used for many ages
- many routes
- considered in the step 1 of WHO analgesic pathway
- good for soft tissue and MSK pain
- supplement opioids to reduce the need for high doses and thus reduce symptoms.
Mechanism of action
- not fully known
= evidence suggests it effects CNS and works on a lower part of the prostaglandin production.
Prostoglandins are involved in pain transition
- forms a components and reduces the reuptake of canabnoids.
Explain NSAIDS
- mild to moderate pain
Use: MSK and tissue injury
- muscle aches
- headache
- low back pain
- osteoarthritis
- tissue sprains
Action
- inhibit synthesis of prostaglandins at a higher level in the chain of production than panadol.
Cox 1: renal bloood vessel and stomach
Cox 2: present in most cells of stomach and at sight of injury.
Coxibs: new NSAIDS spring in Cox 2 so there is less irritation in the stomach as this is where they are primarily found.
What are some examples of non selective NSAIDS
Ibuprofen (Nurofen - oral)
Naproxen (Naprosyn - oral)
* Diclofenac (Voltaren - oral)
* Indomethacin (Indocid -
oral/PR)
* Ketorolac (Toradol - IM / IV)
- high risk of gastric irritation
Effect Cox 1 and 2 so can cause gastric irritation
What are some examples of Cox-2 specific NSAIDS
Celecoxib (Celebrex – Oral)
What are some examples of long acting NSAIDS
Meloxicam (Mobic - Oral)
- long acting NSAID
- good for arthritis
Preferential but not Cox 2
Explain opoids
Moderate to sever
Acute or persistant
- great in multimodal use
MOA: acts as agonists at receptor sites in the brain, spinal cord and other sites of the CNS thus blocking the brains ability to perceive pain.
Instead they stimulate the plaseure centeres of the brain and induce euphoria
3 primary recpetors:
- mu (μ), delta (δ) and kappa (Ќ)
- Analgesia is mediated mainly via the μ receptor
How does morphine work?
- activation of opoid receptor in the neuron
- release in Gabba which causes neighbouring cells release dopamine
- Gabba binds to the nociceptor
- activation of the opioid receptor cause a change in the cells ad inhibits the production of subsatnce P so no transmission can occur in synaptic cleft and thus modulated pain perception
= works to dull the pain and block the signals getting to the presynaptic neuron on the noceptor.
What are some of the most common opoids and what are their routes of administration, indications and points of pratice?
Morphine: most commonly used, various routes
Fentanyl: rapid action; strong; often used for simple and fast procedures; cancer pain; various routes
Oxycodone: oral; used as a step down agent from IV opioids
Hydromorphone: 5 x potent as morphine; various routes; used in cancer and palliative situations
Methadone: oral, long action; for persistent pain, used for substance users to transition from addiction; often daily doses
Pethidine: less used, offers no advantage over other opioids;
Codeine: oral with other drugs e.g. paracetamol
Buprenorphine: SL, IM, SC, TD; long action, used for substance users to transition from addiction; often daily doses
Explain tramadol
= synthetic, weak opioid with multiple actions
1) works on opoid MU receptors
2) Enhances noradrenergic (40%) inhibition
3) Enhances serotonergic (20%)
inhibition
- moderate pain
As it is a weak opoid;
- Reduced incidence of respiratory depression
- Lower abuse potential
- Less constipating
ROA: Oral/parenteral
Explain ketamine
= NMDA antagonist (N‐methyl‐D‐aspartate)
- corsses the blood brain barrier for acute onset pain relief.
- Dissociative anaesthetic agent as causes various effects in mood and etc
- hallucinations, panic attacks, paranoia
- Ketamine treatment effective for relief of postoperative pain
- For acute and persistent pain
- Often used with an opioid for improved analgesia & opioid sparing. Then don’t get the extra effects of ketamine
Explain canabis
Acts on the CNS
- becoming more mainstreem trestment
= acts on the canaboid receptors of the brain
- canabnoids and turpines (active ingredients) are delivered though the blood stream, digestive, lungs, topical.
- bind with receptors to suptess signs including pain, nausea, depression and boost signals of euphoria and apetite.
Cannabinoids bind with the endocannabinoid
receptors, suppress signals such as pain, nausea and
depression, boost signals of appetite and euphoria.
- still being studied
- for people with presistent pain while it reduced the need for opoids it did not show anything to reduce long term use.
Explain anticonvulsants
e.g.gabapentin or pregabalin
= modulate neurotransmitter release
- reduction is neurotransmitter activity and thus helps with neuronal pain.
- 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
Explain antidepressants
= work on the block of serotonin and noradrenaline + adrenaline and histamines.
- used in a lower dosage for pain
- reduced delay of action
Category includes: tricyclic antidepressants (TCAs),
selective serotonin reuptake inhibitors (SSRI) and serotoninnorepinephrine reuptake inhibitors (SNRIs).
Explain MORNRI
e.g. 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
- reduction in physical dependance and reduced level of gastric impacts
Explain the local analgesic of Lignocaine
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)
Explain Capsaicin
= Capsaicin is an alkylamide found in capsicum
- works by depleting substance P
- 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 effe
Describe balanced analgesia
- class of medications should be treating the pathophysiology of the pain!!
We must optomise the drug giving
- re-emptive analgesia e.g. pre symptoms so we anticipate it
- regular analegsics
- check for break through pain
- address side effects
Describe the analgesic corrodior
- analgesia is not to high and causing side effects but not to low that they are feeling pain.
What is the WHO pharam treatment strategy/guidelines for pain treatment?
- treat the underlying cause
- Individualised therapy
- Use a systematic approach
- a two or three step strategy e.g. pharm and non pharm or multi modal - 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
What are the recommendations of WHO pain management?
- 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
What are the steps of the WHO analgesic ladder?
Step 1
- non opoid aka panadol
- non pharm
- + or - adjuncts
Step 2
- weak opoids or NSAID
- e.g. tramadol
- + or - adjuncts
Step 3
- opioids or IV
- + or - adjuncts
- fentnal
Developed for co=ancer ain so may not be appropriate for all pain
Explain the latter 4 step analgesic stairs
- nonopoid, analgesics, NSAIDs
- weak opoids
- Strong opoids, methadone, oral administration, transdermal path
- nerve block, rpidurals, PCA pumps, neuroleptic block therapy, spinal blocks
What are some ways we can change administration to boost effect and reduce symptom?
- Oral
- Rectal
- Intermittent IM or SC injection
- Transdermal
- SC infusion
- IV infusion
- Patient Controlled Analgesia (PCA)
- Epidural
- Intrathecal
- Other regional technique
Which population groups may need extra consideration when treating acute pain?
- Children
- Pregnant patients
- Elderly patients
- Aboriginal and cultural groups
- non‐English speaking people
- Patients with cognitive behavioural and/or sensory impairments
What are some patient co-morbidities we need to consider when treating pain?
- Age
- Renal or liver impairment
- Opioid tolerance
- Substance abuse
- may need higher doses
- Respiratory compromise
- Insulin dependent diabetes
- Cardiac Disease
What are the 3 phases of pain management plan?
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
What are some considerations when treating persistant pain?
- often multifaceted and needs a multimodal approach.
- 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
What is the rational for multimodal appraoch?
- Target multiple mechanisms of pain conditions, addressing both nociceptive (tissue) and neuropathic (nerve) 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
What are some components of a multimodal therapy for persistent pain?
- multiple drugs
- psychological therapy
- active physiotherapy
- peripheral stimulation and interventional therapy
What are complementary or alternative medicines approaches
= add to a western medication in a way that look at the whole person and work long side the wester approach.
The majority of patients suffering from pain due to
musculoskeletal conditions will use some form of CAM
How can you tailor treatment to the patient?
- 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
What are the 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
- 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
What are the 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
Explain accupunture
- Ancient Chinese medical procedure involving insertion
and manipulation of needles
= stimulates secretion of endorphins, serotonin, and noradrenaline in the CNS to make people feel good.
Potentially also works by constricting or dilating
blood vessels due to release of vasodilators such as histamine
Explain cognitive therapy
Goal
- 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
Explain CBT
= psychological technique that teaches people to reframe thoughts.
- change the pattern of thinking to alter the perception of symptoms.
- reduces threat of pain
- Studies of CBT for distress and pain in patients with
breast cancer have shown significant improvements in
these symptoms
- 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.
What is involved in CBT?
= 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
e.g. use a diary to record their pain progression
Explain hypnosis as a pain management strategy?
= creates a state where its resembles sleep and the persons perception and memory can be altered.
Results in increased responsiveness to suggestion
For example, may be used for;
- burns dressing
- assistance with childbirth pain
- preparation of patients for surgery.
Explain nutrition as a pain relief strategy?
Protein required
- Specific amino acids for neurotransmitters
- tissue building and maintenance, e.g. muscles
Reduce sugar and starchy carbohydrates
- people can put on weight from comfort eating. Some evidence to suggest that opoids make one crave sugar.
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
Explain herbal/other strategies as pain management options.
Neuropathic pain
- Capsaicin= works on receptors Capsaicin receptors and over time this cuts off the sensation to the receptors.
Rheumatoid Arthritis
- Gamma linolenic acid (GLA): evening primrose oil= these acids in the oil aid in maintaining joint structure and function.
Osteoarthritis
- Fish oils/Krill oil
= takes 3 months until they get an effect
- some evidence it reduces the need for non steroidals.
Explain massage therapy as a pain relief mechanism
Touch is the most instinctive response to pain.
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
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
Explain mindfulness/meditation as a pain relief strategy
= if you can calm and focus your mind and body, you
may be able to control your pain and degree of feeling
Explain music therapy as a pain relief strategy
= 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
Explain spinal and joint manipulation as a pain relief strategy
= easy movement to the body and resume abnormalities and re-establism normal function of the body.
Includes massage, stretching and joint manipulation
Used by:
- Chiropractors
- Osteopaths
- Physiotherapists
- Used to treat a range of musculoskeletal problems
E.g. low back pain
Explain Transcutaneous Electrical Nerve Stimulation (TENS) as a pain relief strategy
= Electrical stimuli on the skin preferentially activate low‐
threshold, myelinated nerve fibres
- Inhibits nociception by blocking transmission along
fibres to the dorsal horn
- modulation aimed strategy
Good for
- low back pain
- arthritic pain
- visceral pain/postsurgical pain
- Delivery/labour pain
Explain Yoga as a pain relief strategy
= 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
Benefits of regular pratice
- 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
What types of drugs effect transduction?
- NSAIDs
- paracetamol
- anticonvulsants
- local anaesthetics
- Topical: NSAISa/capsaicin
