Mechanisms of Anaesthesia

Question 1

Which type of analgesia blocks nerve conduction?

Answer 1

Local anaesthetics

Question 2

Where do delta receptors act as analgesics?

Answer 2

Spinal

Peripheral

Question 3

Which type of opioid receptors are associated with sedation dysphoria and hallucinations?

Answer 3

Kappa

Question 4

What are the respiratory effects of opioids?

Answer 4

Apnoea

Question 5

What are the cardiovascular effects of opioids?

Answer 5

Orthostatic hypotension

Question 6

How can morphine cause asthma attacks?

Answer 6

Causes mast cell degranulation which triggers bronchospasms

Question 7

How do opioids cause nausea?

Answer 7

Act on CTZ outside the BBB

Decrease motility via enteric neurons via mu and delta receptors

Question 8

What are the GI side effects of opioids?

Answer 8

Nausea
Vomiting
Constipation
Increased intrabilliary

Question 9

What are the CNS effects of opioids?

Answer 9

Confusion, euphoria, dysphoria, hallucinations, dizziness, myoclonus

Question 10

How is morphine metabolised?

Answer 10

Glucorinidation at 3 and 6 position to M3G and M6G

M6G excreted by the kidney

Question 11

Which is the active metabolite of morphine?

Answer 11

M6G

Question 12

Is oxycodone more/less potent than morphine?

Answer 12

3x more

Question 13

What is diamorphine mostly used for?

Answer 13

Severe post op pain

Labour

Question 14

Which is more lipophilic morphine or diamorphine?

Answer 14

Diamorphine

Question 15

What is codeine metabolised to and how?

Answer 15

Via p450s in hepatic metabolism

To morphine

Question 16

How is fentanyl given?

Answer 16

IV

Transdermal or buccal in chronic pain

Question 17

How do opioids works as analgesics?

Answer 17

Act to open inhibit VGCCs and open K+ channels on projection neurons of nociceptors

Question 18

Which receptor is responsible for most of the analgesic action of opioids?

Answer 18

Mu

Question 19

Describe the onset of action of pethidine

Answer 19

Rapid (when given IV, IM, s/c)

Question 20

Which metabolite of pethidine causes seizures?

Answer 20

Norpethidine

Question 21

What is the problem with use of pethidine in labour?

Answer 21

Very potent so causes resp depression in babies

Question 22

What is buprenorphine?

Answer 22

Long acting partial agonist of opioids

Question 23

How is buprenorphine administered?

Answer 23

Injection

Sublingual

Question 24

What is tramadol

Answer 24

Weak mu opioid receptor agonist

Question 25

What is though to be the main mechanism of action of tramadol?

Answer 25

Potentiates the descending serotonin system | And adrenergic system from the LC

Question 26

Other than opioid receptors where does methadone act?

Answer 26

K channels NMDAR 5HT recs

Question 27

How is methadone administered?

Answer 27

Oral

Question 28

What is methadone used for?

Answer 28

Addiction | Cancer

Question 29

What is naloxone?

Answer 29

Competitive antagonist of mu receptors (kappa and delta a lil)

Question 30

What is naloxone mainly used for?

Answer 30

Reversal of opioid toxicity

Question 31

Why does the use of naloxone in opioid overdose need to be monitored?

Answer 31

Has a short half life | Some opioids still acting

Question 32

What are alvimopan and methylnaltrexone used for?

Answer 32

Reduce the GI effects of chronic opioid use

Question 33

Outline the mechanism of action of NSAIDs

Answer 33

Inhibits COX-1 and COX-2 to reduce the synthesis and accumulation of prostaglandins

Question 34

Outline the production pathway of prostaglandins

Answer 34

Phospholipids converted to arachidonic acid by phospholipase A Arachidonic acid converted to endoperoxides which COX1 and 2 Endoperoxdies to prostaglandins isomerase Prostaglandin isomerase to prostaglandins

Question 35

Which group of drugs selectively inhibids COX-2?

Answer 35

coxibs

Question 36

Why is COX2 sometimes selectively inactivated?

Answer 36

Bc COX2 is induced locally at sites of inflammation by various cytokines Most of the therapeutic benefit comes from this

Question 37

What do NSAIDs decreased recruitment of?

Answer 37

Leukocytes

Question 38

What occurs if NSAIDs cross the BBB?

Answer 38

suppress the production of pain producing prostaglandins in the dorsal horn

Question 39

Why do NSAIDs have limited analgesic activity?

Answer 39

Multiple signalling pathways do not involve arachidonic acid metabolism

Question 40

What might long term administration of non-selective NSAIDs cause?

Answer 40

GI damage | Nephrotoxicity

Question 41

Why do kidneys get damaged with NSAIDs?

Answer 41

COX-2 constitutively expressed by kidney

Question 42

Why is the use of coxibs limited?

Answer 42

They are prothrombotic

Question 43

What is the proposed pathology behind neuropathic pain?

Answer 43

Down regulation of mu opioid receptors following injury

Question 44

How does gabapentin act?

Answer 44

Reduces cell surface expression of an alpha2delta-1 group in the VGCC of sensory neurons To decrease the weirdly high amount of neurotransmitters released

Question 45

What is the first line treatment of neuropathic pain?

Answer 45

Tricyclic antidepressants

Question 46

Give examples of tricyclic antidepressants

Answer 46

Amitriptyline Nortryptyline Desipramine

Question 47

How do tricylic antidepressants work?

Answer 47

Act centrally by decreasing the reuptake of noradrenaline (and 5HTfor venlafaxine)

Question 48

How does carbamazepine work?

Answer 48

Blocks VGNCs which are upregulated in damaged nerve