Pain, nociception and analgesia 3 Flashcards
How do analgesics work?
They reduce peripheral nociception and sensitisation, they increase descending inhibition of nociception and reduce primary afferent nociceptive transmission and/or central sensitisation.
What does NSAIDS stand for?
Non-steroidal anti-inflammatory drugs.
What is used to treat mild pain?
Non-opiod NSAIDS, ibuprofen, paracetamol and aspirin.
What is used to treat persisting moderate pain?
Low-potency opioids such as codeine, tramadol and buprenorphine.
What is used to treat persisting severe pain?
High potency-opiods such as morphine, fentanyl and oxycodone.
What are two opiate drugs?
Morphine and heroin.
What are the differences between opiates and synthetic opioids?
Opiates are naturally derived from opium whereas synthetic opioids are drugs that bind to opioid receptors.
Give examples of opiates.
Morphine and codeine.
Give some examples of synthetic opioids.
Heroin, oxycodone, methadone, pethidine, fentanyl, buprenorphine, butorphanol.
What are some unwanted effects of opioids?
Respiratory depression, pupil constriction, reduced gastrointestinal motility, sedation, physical dependence and catatonia.
What receptors do strong opiates affect?
Mu, delta and kappa.
What are some strong opiates?
Morphine, methadone and fentanyl.
What are some weak opiates?
Codeine and buprenorphine.
Why is tolerance an issue with opioid drugs?
Continued use requires increased doses for an equivalent effect.
What are the different forms of administration of opiates?
Pills, intravenous injections, epidural, transfermal patch and lollipop.
What opiates are taken in pills?
Morphine and codeine.
What opiates are intravenously injected?
Morphine, diamorphine and fentanyl.
What opiates are taken epidurally?
Fentanyl and pethidine
What opiates can be taken using a transdermal patch?
Fentanyl.
What opiates can be taken in a lollipop form?
Fentanyl.
What are the properties of NSAIDS?
Analgesic, anti-inflammatory, anti-pyretic, all the effects are related to decreased prostaglandin synthesis.
What are NSAIDs inhibitors of?
COX inhibitors.
What are some of the disadvantages of NSAIDS?
Skin reactions, severe gastric irritation, nausea, vomiting, kidney disorders, cardiovascular effects, bronchospam.
What supraspinal effects does morphine have?
Pre and postsynaptic reduction of GABA inhibition, increased excitatory output, increased activity of 5HT neurones, increased output from 5HT neurons and increased 5HT inhibition of second order neurons.
What spinal analgesic effects does morphine have?
Decreased release of glutamate at primary afferent synapses, reduced action potential in primary afferent neurons and direct inhibition of second order afferent neurons.
What peripheral analgesic effects does morphine have?
Decreased excitability of nociceptor terminals and decreased Ca2+ signalling in nociceptor terminals.
What is the most widely used analgesic agent?
NSAIDs.
Give some examples of NSAIDs.
Aspirin, ibuprofen, diclofenac, paracetamol.
What pathway does NSAIDs affect?
They prevent prostaglandin being synthesised so the prostanoid receptor cannot be activated. This is due to the effect of COX being inhibited - cyclo-oxygenase1/2. The proastanoid receptor is involved in modulation at nociceptors.
What effect do prostaglandins have?
They do not cause pain themselves but they sensitive bradykinins to increase nociception ?? i think ?? They block potassium efflux, making them more sensitive.
Why do NSAIDs have a lot of adverse effects?
Both COX-1 and COX-2 are blocked.
How can kidney disorders arise with NSAIDs?
Paracetamol overdose.
What are some specific COX-2 inhibitors?
Rofecoxib and celecoxib.
What are the benefits of specific COX-2 inhibitors?
There are less side effects, but there are cardiovascular complications.
What are other analgesic approaches?
Tricyclic antidepressants, antiepileptic drugs, glutamate receptor blockers, neurokinin receptor blockers, cannabinoid receptor agonists, vanilloid receptor blockers.
How do tricyclic antidepressants and antiepileptic drugs work to treat analgesia?
Na/Ca channel blockade - reduce primary afferent transmission.
How do glutamate and neurokinin receptor blockers treat analgesia?
They block primary afferent transmission but have severe central side effects such as psychosis.
How can cannabinoid receptor agonists be used for analgesia?
They have central and peripheral nociceptor effects that can be used for neuropathic pain such as MS.
How do vanilloid receptor blockers act to treat analgesia?
ATP receptor blocker - they block the detection of peripheral noxious signals.
