Acute and Chronic Pain Management - Neuropathic pain, Opioids, Palliative care Flashcards
How is neuropathic pain defined?
Pain following nerve damage or disruption. Often difficult to treat and poorly responsive to standard analgesia.
What are some examples of neuropathic pain conditions?
Diabetic neuropathy
Post-herpetic neuralgia
Trigeminal neuralgia
Prolapsed intervertebral disc
What are the first-line treatments for neuropathic pain according to NICE 2013 guidance?
Amitriptyline
Duloxetine
Gabapentin
Pregabalin
What should be done if the first-line drug for neuropathic pain does not work?
Try one of the other first-line drugs.
Drugs are typically used as monotherapy, so switch if not effective.
When may tramadol be used in managing neuropathic pain?
As ‘rescue therapy’ for acute exacerbations of neuropathic pain.
What is the role of topical capsaicin in neuropathic pain management?
Used for localized neuropathic pain, such as post-herpetic neuralgia.
What should be considered for patients with resistant neuropathic pain?
Referral to pain management clinics may be beneficial.
What is the first-line treatment for trigeminal neuralgia?
Carbamazepine.
What are opioids and where do they act?
Substances like endorphins, semi-synthetic, and synthetic compounds. Act on opioid receptors in the CNS, PNS, and other tissues.
What are the G-protein coupled receptors involved in opioid action?
Mu (µ)
Kappa (κ)
Delta (Δ)
Where are Mu (µ) receptors located and what are their effects?
Located in the brain, brainstem, and spinal cord.
µ1-receptors: Analgesia
µ2- and µ3-receptors: Respiratory depression, reduced GI motility, vasodilation, pupillary constriction (in overdose)
What effects are associated with Kappa (κ) receptors?
Cognitive effects
Dysphoria
Hallucinations
Depressed consciousness
Where are Delta (Δ) receptors located and what do they do?
Located in the brain and brainstem.
Potentiate µ-receptors, enhancing analgesia, respiratory depression, and dependence.
What does NICE recommend for starting opioid treatment in palliative care?
Regular oral MR or immediate-release morphine (based on patient preference)
Oral immediate-release morphine for breakthrough pain
Initial dose: 20-30mg MR daily, 5mg for breakthrough pain (e.g., 15mg MR twice daily, 5mg oral as needed)
Use oral MR morphine over transdermal patches
Prescribe laxatives
Nausea and drowsiness are usually transient; adjust dose if persistent
How is opioid metabolism affected by renal impairment?
Most metabolites are excreted by the kidneys.
Renal impairment can cause accumulation of metabolites, increasing toxicity risk, especially with active metabolites.
