Analgesics and sedative drugs Flashcards
What different tools can be used to assess pain?
McGill Pain Questionnaire
Brief pain inventory (body map)
Memorial Pain Assessment Card (faces and numbers)
What is used to guide the treatment of pain?
WHO analgesic ladder.
According to the WHO analgesic ladder, what types of analgesia would you give someone for mild, moderate and severe pain?
Mild - NSAIDS + Paracetamol
Moderate - Codeine, Dihydrocodeine, Tramadol
Severe - Morphine, Diamorphine, Fentanyl
What is an adjuvant medication in pain management?
A medication that is commonly used for something else, but is also used for pain e.g. antidepressants in chronic pain.
What type of medication is preferred for patients with primary chronic pain?
Anti-depressants.
What is breakthrough pain?
Where patients experience a peak or rise in pain in the middle of their analgesia when the analgesic affect should still be present.
Do NSAIDs affect the PNS or CNS?
Both, but mainly PNS.
What is the MOA for NSAIDs?
Ibuprofen + Naproxen: Competitive inhibitors of COX (reversible action).
Aspirin: Irreversible inhibitor of COX.
Both reduce the production of prostaglandins (as COX is needed for the conversion of arachidonic acid into prostaglandins).
Prostaglandins increase Na+/Ca2+ influx into nociceptors, making them more sensitive to thermal, mechanical or chemical stimuli. Thus blocking production of prostaglandins, makes them less sensitive.
Which type of COX can be induced by inflammatory stimuli?
COX 2 - Aids in pain, inflammation + fever.
Which physiological functions does COX 1 have?
Protects gastric mucosa (PGE2)
Renal homeostasis (PGE2/PGI2) - effects on Na+ + fluid retention.
Why is there a risk of gastric ulcers or renal problems with NSAIDs?
NSAIDS block COX1+2 - blocking COX2 reduces inflammation + pain, but blocking COX1 will result in less production of PGE2, and therefore it’s protection of the gastric mucosa.
COX1+2 also both help with renal homeostasis, and blocking these may result in renal problems.
Which drugs can selectively block COX2?
COXIBs: Selective Cox-2 inhibitors.
Does paracetamol affect the PNS or CNS?
Mainly the CNS - but no one really knows how.
What is paracetamol thought to inhibit?
COX 1/2/3(if there is a COX3)
Also thought to affect the endocannabinoid and serotoninergic systems.
How does paracetamol get metabolised?
Through the liver - which is why is can cause hepatic necrosis and liver failure in an overdose.
How is paracetamol different from NSAIDs?
Paracetamol doesn’t injure the gastric mucosa, is well tolerated in peptic ulcer disease + has no effect on platelets.
What is the primary drug class for the acute management of moderate to severe pain?
Opioids.
Which opioids are naturally occuring?
Morphine, codeine.
Which opioid is semi-synthetic?
Diamorphine.
Which opioid is fully synthetic?
Fentanyl - also the most potent.
Opioid receptors (Miu, Delta + Gamma) are all coupled to which second messenger protein?
Gai
Which opioid receptor is responsible for most of the analgesic + some unwanted effects?
Miu
What is the MOA of opioids?
Activates Gai - Inhibits AC –> Reduces cAMP (affecting phosphorylation) –> Voltage gated Ca2+ channels inhibited (so reduces NT release) + K+ channels activated (causing hyper-polarisation of the cell membrane).
What is a ceiling dose?
When a dose of medication is increased past a certain amount, but the therapeutic effect no longer increases with it.
