Pain + Analgesics Flashcards
What are the main categories of pain?
Nociceptive (tissue damage, acute)
Neuropathic (neuronal damage, chronic)
What is hyperalgesia
Hypersensitivity to pain
What is allodynia?
Triggering of a pain response from stimuli which do not normally provoke pain
What is nociceptive pain?
Caused by physical damage resulting in activation of free nerve endings
What is neuropathic pain?
Results from neuronal damage and includes symptoms such as shooting/ burning pain and paraesthesias (e.g. tingling, numbness, pins and needles)
Give examples of neuropathic pain
Phantom limb Trigeminal neuralgia Malignant pain Post-stroke (thalamic) pain Post-herpetic pain Complex regional pain syndrome (CRPS)
Give examples of nociceptive pain
Lower back pain
Myofascial (muscle) pain
Arthritis
Visceral pain (e.g. cystitis, pancreatitis)
What are the 5 types of headache?
Tension Sinus Migraine Cluster Medication overuse headache
What type of headache is a clinical emergency?
‘Worst ever headache’
Subarachnoid haemorrhage
What is the standard treatment for tension headaches?
NSAIDs
Determining triggers
What is the standard treatment for sinus headaches?
Decongestant
Antihistamines
Steroids
What is the standard treatment for migraine headaches?
3 step approach:
1. NSAIDs +/- antiemetics
2. Rectal NSAIDs +/- antiemetics
3, Anti-migraine drugs (triptans)
[Avoid opioids!]
Why does chronic pain develop?
Badly managed acute pain Emotional sensitivity/ poor coping skills Previous experience Surgical complications Genetic predisposition
What are the non-pharmacological options for pain management?
Exercise/ physiotherapy
Acupuncture
Transcutaneous Electrical Nerve Stimulation (TENS)
What invasive procedures are used to manage pain?
Nerve blocks/ injections (e.g. steroids)
Ablation (removal of neurones from region of pain)
Implants (e.g. pumps, neuromodulators)
What pharmacological options are available for managing nociceptive pain?
NSAIDs
Opioids
What pharmacological options are available for managing neuropathic pain?
Tricyclic antidepressants (amitriptyline, nortriptyline)
Antiepileptics (gabapentin, pregabalin)
Can be used in combination with carbamezapine
What is the WHO ladder for cancer pain control?
Pain free
Low level pain - treated by non-opioid analgesic
Mid level pain - treated by weak opioids
High level pain - treated by strong opioids
What is the MoA for NSAIDs?
Blocks production of prostaglandins by inhibiting COX enzymes (1+2)
Which COX enzyme is involved in the inflammatory response?
COX enzyme 2
What NSAIDs are specific COX-2 inhibitors?
Celecoxib
Etoricoxib
How do NSAIDs affect cells at a neuronal level?
Removal of prostaglandins
What is salicylism?
Salicylate toxicity due to ingestion of NSAIDs
How can NSAID intoxication be treated?
Fluid replacement
Haemodialysis
Activated charcoal
IV Lorazepam/ Diazepam (for seizures)
What are the key symptoms of NSAID intoxication?
Tinnitus Pulmonary and cardiovascular symptoms CNS symptoms Renal failure Coma
What are the 3 groups of opioids?
Agonists
Partial agonists (or mixed agonists-anatgonists)
Antagonists
What drugs are opioid agonists?
Strong = morphine, diamorphine, tramadol Weak = codeine, dihydrocodeine
What drugs are opioid partial agonists/ mixed agonist-antagonist?
Buprenorphine
What drugs are opioid antagonists?
Naloxone
Naltrexone
Where in the CNS do opioids act?
Mu, kappa, delta opioid receptors (OP1-4)
ORL1
What are the key side effects of opioids?
Respiratory depression
Conscious depression/ mood alterations
Miosis
What are the key indicators of opioid overdose?
Pupillary constriction
Respiratory depression
Coma (GCS <7)
What treatment is used for opioid overdose?
Opioid antagonists (e.g. naloxone, naltrexone)
Oxygen
Glucose
Thiamine
What drugs can be used as migraine prophylaxis?
Beta-blockers
Amitriptyline (tricyclic antidepressant)
What is the MoA of opioids?
Mimic endogenous opioids acting on opioid receptors to modulate pain at all CNS levels.
Hyperpolarises neuron so it is less likely to fire when a stimulus comes through
