Pain Flashcards
What is pain
Unpleasant sensory and emotional experience
Associated with actual or potential tissue damage
What are simple analgesics
Paracetamol
NSAID
What are opioids
Codeine Dihydrocodeine Co-codomol (8/500 or 30/500) or codydramol Morphine Oxycodone Fetanyl
What are other options for pain relief
Tramadol - small opiate + 5HT / NA reuptake inhibitor TCA Anti-convulsants Ketamine - NMDA receptor antagonist LA Nerve block Spinal and epidural Topical - capsaicin
Action of paracetamol
Inhibits prostaglandin synthesis
What is it good for
Mild pain
Very effective with NSAID
Severe pain in combination with other drugs
SE
Almost none
Very cheap and safe
Liver damage in overdose so caution in impairment
How is it given
Oral
Rectal
IV - adjust dose according to weight
Action of NSAID (Ibuprofen / Aspirin / Diclofenac)
Inhibit enzyme cyclo-oxygenase which is used in prostaglandin and thromboxane synthesis
What are NSAID good for
Nociceptive pain
In combination with paracetamol
When do you have caution with NSAID
GI pathology - peptic ulcer Bleeding / anti-coagulation Impaired renal Sensitive asthmatics Elderly Aspirin CI in children due to risk of Reye's
What do opioids do and how do you give
Act peripherally and centrally at opioid receptor to inhibit transmission off pain (analgesia)
Can give by all route but must convert dose
What are the SE of opioids
Resp depression as decreased sensitivity to CO2
N+V so give with anti-emetic
Constipation - decreased motility
Miosis
Other Headache Urinary retention Bradycardia Hallucination Sedation
Release of Histamine
- Bronchospasm
- Hypotension (vasodilation)
- Itch and wheels
- Phlebitis
Endocrine
- Inhibition of ACTH / prolactin / FSH / LH
- Increased ADH
Why are opioids controlled drugs
Due to addictive nature
Risk of tolerance and dependence
What is morphine useful for
Moderate - severe acute nociceptive pain I.e. hip fracture
Give 10mg IV
Chronic cancer pain
What are disadvantages of morphine
Significant first pass metabolism
COnstipation
Resp depresion
Addiciton
What should oral dose of morphine be compared to IV
3x larger
What is codeine good for
Mild-moderate acute nociceptive pain
Best given regularly with paracetamol
What is codeine not good for
Chronic pain
Cause constipation
What is tramadol and how does it act
Weak opioid plus inhibitor of serotonin and Na reputake
Acts at spinal cord to dampen pain transmission
Benefits of tramadol
Less resp depression
Can be used with other opioids and simple analgesia
Not a controlled drug - now controlled
When do you use
NO justification as first line unless other opioid CI
Disadvantages
N+V
Caution in epilepsy as lower seizure
Caution if use with TCA / SSRI as lower seizure
How does amitriptyline (TCA) work
Increases descending inhibitory signals
What is it good for
Neuropathic pain
Depression / poor sleep
Disadvantages
Anti-cholinergic SE
- Glaucoma
- Urinary retention so do not give if BPH
- CI MG