GLS 01 Control of Pain Flashcards
Why is paracetamol sometimes not classified as an NSAID?
Because paracetamol only has minor anti-inflammatory activity because it is inactive in the periphery.
List 3 main therapeutic effects of NSAIDs.
1 - Antipyretic.
2 - Analgesic.
3 - Anti-inflammatory.
Which drug class does ibuprofen belong to?
NSAIDs.
How does naproxen differ from ibuprofen?
- Ibuprofen is metabolised faster than naproxen. Naproxen therefore lasts longer than ibuprofen.
- Naproxen is more potent than ibuprofen.
List 4 side effects of NSAID use.
What causes these effects?
1 - Increased risk of GI bleeds (due to loss of prostaglandins).
2 - Clotting (due to changes in thromboxane and prostacyclins).
3 - Aspirin-sensitive asthma (inhibiting COX shunts arachidonic acid to lipoxygenase pathway, resulting in an increase in leukotrienes).
4 - Acute kidney injury (prostaglandins regulate renal blood flow).
How does transcutaneous electrical nerve stimulation (TENS) work?
- Stimulation of a large diameter A-beta mechanoreceptor fibre sends excitatory signals to the inhibitory interneurone at the dorsal horn of the spinal cord.
- This decreases the output of the pain fibres.
What drug class does morphine belong to?
Opiates.
Describe the mechanism of action of morphine.
Morphine acts on opioid receptors in neurones at the dorsal horn. BInding of morphine to opioid receptors causes:
1 - Suppression of glutamate release.
2 - Hyperpolarisation.
- This results in blockade of the ascending signal of pain.
List 2 side effects of morphine use.
1 - Respiratory depression (morphine binds to mu receptors in the respiratory centres of the brain, causing hyperpolarisation and therefore reduced respiratory drive).
2 - Constipation.
How is respiratory depression due to morphine use treated?
By administering naloxone, an opioid receptor antagonist.
