Pain and analgesics 4 (analgesic drugs) 2.0 Flashcards
Which method of administering analgesics can be patient controlled?
Intravenous injection
What is an epidural?
Delivering a drug directly into the spinal cord
When is epidural administration used?
Childbirth
Why is epidural administration used in childbirth?
Know where pain will come from so know where it will enter the spinal cord so can administer drug directly into that bit of the spinal cord
What are the benefits of epidural administration of drugs in childbirth?
Minimises opioids going into the mothers bloodstream
Why is fentanyl used often in surgery?
Short half life–> wears off quickly
Which drugs are administered via a transdermal patch?
fentanyl and buprenorphine
Big advantage of transdermal patches?
Good way to steadily administer drug, keep dose at a consistent level
Which level of administration is used for treating chronic pain?
Transdermal patch
What is buccal absorption?
Through the mouth
Why is fentanyl absorbed orally?
It is lipophilic
Benefit of a fentanyl lolipop?
Quick way of getting drug into bloodstream
Examples of nonsteroidal anti inflammatory drugs?
Aspirin, ibuprofen, diclofenac, paracetamol
What effects do NSAIDs have?
Anti inflammatory, antipyretic, analgesic
Antipyretic meaning?
Decreases fever
What normal effect of NSAIDs can paracetamol not do?
Be anti-inflammatory
How do the additive properties of paracetamol and ibuprofen work?
The positive effects are additive but the toxic effects are not
Who cannot take paracetamol and ibuprofen?
Childeren
What do all NSAIDs inhibit?
Prostaglandin synthesis
What do prostaglandins activate?
Prostanoid receptors
What happens when prostanoid receptors are activated?
Sensitisation of nociceptors
What is the first molecule in prostaglandin synthesis?
Phospholipids
What are phospholipids converted to in prostaglandin synthesis?
Arachidonic acid
What catalyses the formation of arachidonic acid from phospholipids?
Phospholipase a2
What is arachidonic acid converted to in prostaglandin synthesis?
Prostaglandin H2
What catalyses the formation of prostaglandin H2 in prostaglandin synthesis?
Cyclo-oxygenase-1 or -2 (COX-1 or COX-2)
What is prostaglandin H2 converted to in prostaglandin synthesis?
Prostaglandin E2 (PGE2)
What catalyses the formation of prostaglandin E2 in prostaglandin synthesis?
PGE synthase
Which step of prostaglandin synthesis do NSAIDs target?
The conversion of arachidonic acid to prostaglandin H2
How do NSAIDs inhibit prostaglandin synthesis?
They block COX-1 or COX-2
Disadvantages of NSAIDs?
Severe gastric irritation, kidney disorders
Where is COX-1 found?
Widespread throughout the body
What is COX 2 exclusively involved in?
Inflammatory response
Inhibition of which specific enzyme causes the desired effects of NSAIDs?
COX-2
Inhibition of which specific enzyme in the prostaglandin synthesis pathway causes causes gastric irritation?
COX-1
Which drugs are COX-2 inhibitors?
Rofecoxib (vioxx), Celecoxib (celebrex)
Main issue with Rofecoxib (vioxx)?
Cardiac side effects
Side effect occurrence in Rofecoxib (vioxx) patients?
1/10,000
What is an example of a disease that taking Rofecoxib (vioxx) or celecoxib (celebrex) helps?
Rheumatoid arthritis
What is neuropathic pain?
Pain unrelated to peripheral nociception
What can cause neuropathic pain?
Peripheral nerve damage, peripheral nerve terminal damage or infection, spinal damage, thalamic stroke
Issue with neuropathic pain?
Does not respond to opioids or NSAIDs
Which drugs work for shingles pain?
Tricyclic antidepressants
Example of a tricyclic antidepressant?
Imipramine
Why, is it thought, that tricyclic antidepressants help with shingles pain?
They boost noradrenaline
Which drugs can be useful in neuropathic pain?
Antiepileptics (gabapentin), cannabinoid receptor agonists
Which condition can cannabinoid receptor agonists be used to treat in the uk?
Multiple sclerosis
Issues with glutamate receptor blockers (e.g. MK801)?
Side effects–> psychotic episode
How do neurokinin receptors work?
Blocking central sensitisation
Issue with analgesics that block central sensitisation?
Would need to take them before any pain is going to occur, as central sensitisation has already occured after pain has been felt