Physioogical Basis Of Pain Managment

Question 1

What are the 3 steps of the analgesic ladder?

Answer 1

Step 1- non-opioid analgesics for mild pain

Step 2- weak opioids for moderate pain (with/without non-opioids)

Step 3- strong opioids for severe pain (with/without non-opioids)

Adjuvant drugs can be added to each step if needed

Question 2

What are examples of non-opioids?

Answer 2

Paracetamol

NSAIDS eg aspirin, ibuprofen etc

Question 3

What are examples of weak opioids?

Answer 3

Codeine

Dihydrocodeine

Question 4

What are examples of strong opioids?

Answer 4

Morphine

Oxycodone

Fentanyl

Question 5

What is the function of NSAIDs?

Answer 5

Commonly used to manage pain

Mechanism of action is to inhibit production of prostaglandins

Inhibit cyclooxygenase and block prostaglandin release- reduce inflammation and pain

Question 6

What are prostaglandins?

Answer 6

Inflammatory mediators

Formation involves COX

Important homeostatic- regulating renal function, platelet formation, vascular endothelial function and integrity of gastric mucosa

Question 7

What is the function of ibuprofen?

Answer 7

Mostly commonly used/prescribed NSAID

Non-selective COX 1/2 inhibitor- inhibits prostaglandin synthesis

Analgesic, antipyretic and anti-inflammatory properties

Mainly used for pain associated with inflammation

Rapidly absorbed following administration- quickly distributed throughout whole body

Question 8

What is the function of codeine (weak opioid)?

Answer 8

Metabolised into morphine in the liver

Exerts its effects by binding to opioid receptors in SC

Widely used analgesic

If it interacts with Sc receptors- block receptors for substance P and inhibit its secretion

Question 9

What is the function of morphine (strong opioids)?

Answer 9

Widely used

Provides effective analgesia

Binds to opioid receptors- widespread in brain, SC etc

Strong affinity for mu receptors (existing on presynaptic neurones in periaqueductal gray region in primary control centre in descending pain modulation)

Question 10

What are the 6 possible routes of administration of strong opioids?

Answer 10

1) oral
2) intravenous
3) intramuscular
4) subcutaneous
5) IV/SC infusions
6) transdermal route

Question 11

What are adjuvant drugs?

Answer 11

Medicines not typically used for pain

In combination with analgesic medicines may be helpful in its management

Some are described as multipurpose

Can be added at any step of the ladder

Question 12

What is the function of antidepressants?

Answer 12

Commonly used in pain management

Enhance activity in descending inhibitory pathways- alleviates pain

Question 13

What are examples of antidepressants as adjuvants?

Answer 13

Tricyclic antidepressants

Selective serotonin reuptake inhibitors