Pain Flashcards
Define chronic pain
o Pain lasting for more than 3 months
o Pain lasting after normal healing
o Often no identifiable cause
Describe the characteristics of cancer pain
Cancer pain tends to be progressive, and is often a mixture of acute and chronic.
Define nociceptive pain
obvious tissue injury illness. Also called physiological or inflammatory pain, has a protective function. Usually described as sharp/dull and well-localised.
Define neuropathic pain
Nervous system damage or abnormality, usually without obvious tissue damage. Does not have a protective function. Described as burning or shooting, not well localised. Includes phantom limb pain.
What combination of features is pathognomonic for neuropathic pain?
numbness + pain
Give four steps in pain physiology
Periphery
Spinal cord
Brain
Modulation
Give some pathological mechanisms for neuropathic pain
• Increased receptor numbers • Abnormal sensitisation of nerves o Peripheral o Central • Chemical changes in the dorsal horn • Loss of normal inhibitory modulation
When is paracetamol used as an analgesic?
Used by itself for mild pain
Used in conjunction with other analgesics for moderate-severe pain
Give three examples of non-steroidal anti-inflammatory drugs
Aspirin
Ibuprofen
Diclofenac
Give two examples of mild opioid drugs
Codeine
Dihydrocodeine
Give three examples of strong opioid drugs
Morphine
Oxycodone
Fentanyl
What are the disadvantages of opioids?
Constipation
Respiratory depression in high dose
Misunderstandings about addiction
Controlled drug
What is tramadol?
Mixed opiate and 5HT/NA reuptake inhibitor
- weak opioid effect plus inhibitor of serotonin and noradrenaline reuptake
Describe the advantages of tramadol
less respiratory depression than morphine
can be used with opioids and simple analgesics
not a controlled drug
Describe the disadvantages of tramadol
nausea and vomiting
Give two examples of antidepressants that can be used as analgesics
amitriptyline
duloxetine
(triciclic antidepressants TCAs)
Why are tricyclic antidepressants useful as analgesics?
they increase descending inhibitory signals
Describe the advantages of using TCAs as analgesics
Cheap
Safe in low doses
Good for neuropathic pain
Also treat depression and poor sleep
Describe the disadvantages of using TCAs as analgesics
Anticholinergic side effects:
- glaucoma
- urinary retention
Give three examples of anticonvulsants that can be used as analgesics
Carbamazepine
Sodium valproate
Gabapentin
How to anticonvulsants provide analgesia in neuropathic pain?
reduce abnormal firing of nerves
Which two groups of drugs are most effective for neuropathic pain?
Antidepressants (esp. tricyclic antidepressants)
Anticonvulsants
Which analgesic treatments work at the peripheral level?
Non-drug treatments: RICE
NSAIDs
Local anaesthetics
Which analgesic treatments work at the spinal cord level?
Non-drug treatments: acupuncture, massage, TENS
Local anaesthetics
Opioids
Ketamine
