Review Note
Last Update: 02/18/2024 05:30 AM
Current Deck: Part 2::6. High Yield Questions::Clinonc
PublishedCurrently Published Content
Front
Discuss
the pharmacological pain management options. Include in your
answer the rationale, advantages and disadvantages for each class of drug
Back
1. Paracetamol/simple
analgesia
MOA: not fully elucidated, but thought to act
centrally, possibly through inhibition of COX pathways.
Advantages:
- efficacy in mild to moderate pain, lack of tolerance/dependency, and lack of
side-effects when taken properly.
- works by different mechanism to other drug classes, may work synergistically and/or reduce requirements for opioids/other agents
Disadvantages: limited efficacy in
cases of more severe pain, potential for hepatotoxicity, and dose ceiling of 4
grams daily.
2. NSAID
MOA: work
via inhibition of cyclooxygenase, an enzyme involved in prostaglandin
synthesis, which is a mediator for pain.
Advantages:
- relatively low risk
profile and efficacy against inflammatory pain.
Disadvantages:
- less efficacy
for more severe cancer pain
- possibility of gastric and/or cardiac
toxicities
- increased risk of bleeding
3. Corticosteroids
MOA: Acutely - works via decreased vasodilation and permeability of capillaries and
decreased leukocyte migration to sites of inflammation. Longer term - binding to
the glucocorticoid receptor mediates changes in gene expression that lead to multiple
downstream anti-inflammatory effects.
Advantages:
- Rapid efficacy
against pain caused by mechanical triggers such as pressure effect from tumouric vasogenic oedema
Disadvantages:
- Wide ranging side effects
- Acute: Gastric ulcer, reflux, peripheral oedema, hypervigilence, cognitive dysfunction, increased appetite
- Late: proximal neuropathy, osteoporosis, metabolic syndrome, hyperglycaemia, cataracts
4. Opioids
MOA: selective binding to opioid receptors to stop transmission of pain
transmission. WHO stepwise management of analgesia suggests using
simpler/aforementioned agents prior to opioids, which are very effective in
severe cancer pain.
Advantages:
- ability to rotate between
different opioids, being able to dose escalate or de-escalate as required, and
flexibility of short vs long-acting and weak vs strong agents.
Disadvantages:
- potential side-effects (e.g. nausea, constipation) and complications (e.g. respiratory depression, tolerance and
dependency).
5. Anti-depressants:
including SNRI’s (e.g.
duloxetine) and TCA’s (e.g. amitriptyline).
MOA: increase the concentration of
serotonin and norepinephrine in the dorsal horn of the spinal cord, increasing
descending inhibition of pain through activation of serotonergic and adrenergic
receptors.
Advantages:
- Particularly beneficial for nerve-related pain. Additionally, may
have added benefit of mood modulation.
Disadvantages:
-lengthy duration
before benefits become apparent
- side-effect profile (including
constipation, dizziness, xerostomia etc).
6. Anti-epileptics:
such as pregabalin and gabapentin
MOA: These bind to voltage-gated calcium channels
in the central nervous system, modulating the release of neurotransmitters
involved in transmission of pain.
Advantages:
- beneficial for neuropathic pain.
- Dose can be
titrated according to pain levels.
Disadvantages:
- Different set of toxicities and
complications (blurred vision, xerostomia) to most other analgesic agents,
although these can still occur fairly commonly.
7. NMDA/Ketamine
Further information, not for memorising (no card)
Exam
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