Analgesics

Question 1

Nociception?

Answer 1

Transmission of noxious stimuli by nociceptors to CNS and thalamus

Question 2

How does pain differ to nociception?

Answer 2

Pain is objective - it has an emotional element

Question 3

NSAIDs

What do they effect?

Answer 3

Non-sterodial anti-inflammatory drugs
Anti-inflammatory
Anti-pyretic
Anti-platelet
Analgesia

Question 4

Mechanism of action of NSAIDs

Answer 4

Inhibit the production of prostaglandin production by inhibiting cycloxygenase

Question 5

Problems with inhibition of COX

Answer 5

COX 1 = important in the gut
COX 2 = activated in inflammation
but COX2 is easier to interact with as it has a large side group

Question 6

How do NSAIDs cause analgesia and inflammation?

Answer 6

Decreased prostaglandin synthesis = decreased sensitisation of nociceptors

Question 7

How do NSAIDs have anti-pyretic properties?

Answer 7

In fever PGE2 synthesis is increased, NSAIDs decrease PGE2 synthesis

Question 8

Why is the NSAID ibuprofen more effective than the NSAID ibuprofen?

Answer 8

Ibuprofen can be administered orally, apically, rectally by aspirin is only oral
More rapidly absorbed, less gastric inhibition and has fewer side effects

Question 9

Difference in properties in paracetamol compared to other NSAIDs?

Answer 9

Paracetamol is not anti-inflammatory or anti-platelet

Question 10

How does inflammation effect paracetamol action?

Answer 10

Less analgesic activity

Question 11

Positives of paracetamol

Answer 11

Very rapidly absorbed
uncommon side effects
oral, rectal and IV administration

Question 12

Problems with paracetamol overdose

Answer 12

Phase II metabolic pathways are saturated so more is metabolised by CYP450 to a toxic metabolite which then causes necrosis of hepatocytes and so liver

Question 13

Name 3 opioids

Answer 13

Codeine, heroin, morphine

Question 14

How do opiates differ to opioids?

Answer 14

Man-made - different chemical structure

Question 15

Which opioid receptor do opioids interact with?

Answer 15

Mu

Question 16

What type of receptor are opioid receptors? Relate to function

Answer 16

G-coupled (Gi) = less excitation of cell

Question 17

Therapeutic effects of opioid analgesics?

Answer 17

Analgesia, euphoria, sedation

Question 18

Why is actual dose of opioids much higher than therapeutic dose?

Answer 18

Erratic absorption and extensive first pass metabolism

Question 19

What is the difference between adverse effects of the CNA and PNS, give examples.

Answer 19

CNS = drowsiness, respiratory depression, tolerance and dependance, vomiting
PNS = histamine release, pinhole pupils, constipation

CNS = more severe

Question 20

Tolerance vs dependance

Answer 20

Tolerance detected within 24hrs but sensitivity returns on withdrawal
Dependence follows abrupt withdrawal