Lecture 16 - Opioids Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is the definition of Pain?

A

An unpleasant sensory and emotional experience associated with or resembling actual or potential tissue damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some endogenous opioids?

A

B-endorphins
Endomorphins
Dynorphins
Enkephalins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 types of pain fibres?

A

A delta fibres
C fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of pain do A delta fibres transmit?

A

Fast sharp pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of pain do C fibres transmit?

A

Slow burning pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What sensory pathway transmits pain?

A

Spinothalamic pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which pain fibres are myelinated and which pain fibres are not myelinated?

A

A delta fibres = myelinated (fast sharp pain)

C fibre = unmyelinated (slow burning pain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where do the primary sensory neurones (A delta fibres or C fibres ) synapse to the second order neurone?

A

Synapse to second order neurone in the Ipsilateral dorsal horn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is considered the pain gate?

A

The point where the primary sensory pain neurones (A delta and C fibres) synapse to the 2nd order neurone in the dorsal horn on the Ipsilateral side of the cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Once the pain fibre has synapsed to the 2nd order neurone on the Ipsilateral cord what happens next?

A

2nd order neurone decussates and ascends to the thalamus where it synapses to a 3rd order neurone going to the cortex
A 2nd order neurone also goes to the limbic system (emotional response to pain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the function of the limbic system in the pain pathway?

A

Emotional control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What carries the sensory dimension in the pain pathway?

What carries the affective/emotional dimension of pain?

A

Sensory = 3rd order neurone to cortex

Affective = 2nd order neurone to limbic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Go to the first slide and label the spinothalamic pain pathway on the left hand side:

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What effect does rubbing an area with pain have?

A

Relieves the pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does rubbing a painful area help relieve the pain?

A

Stimulating mechanoreceptors leads to their primary sensory neurone Stimualting inhibitory encephinergic neurones that lead to the secondary sensory neurone in the dorsal horn prevention pain reaching the cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the neurotransmitters from inhibitory interneurones that synapse onto the 2nd Order sensory neuorne in the dorsal horn?

A

GABA
Enkephalins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What class of molecule arer enkephalins?

A

Endorphins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What receptors do endorphins/enkephalins act on?

What do they do?

A

Mu opioid receptors

Inhibit pain transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What neurotransmitters are produced by descending fibres that inhibit the activation of the 2nd order sensory neurone prevntinig pain?

A

Noradrenaline
5-HT (serotonin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Go to the first slide and label the right side pain pathway:

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What part of the CNS have high levels of Mu opioid receptors so are important in pain?

A

High. Levels in Brain
Periqueductal grey matter in midbrain
Reticular formation (grey matter in medulla)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the pathway for altering pain threshold during stress?

A

Amygdala to periaqueductal grey matter then travels to reticular formation in medulla then to the dorsal horn in the cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the pathway for altering pain threshold during the menstrual cycle?

A

Hypothalamus sends axons to periaqueductal grey matter in the midbrain
Then axons sent from here to the reticular formation in the in the medulla
Then axons sent from here to the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the thought process behind the cause of opioid drug addiction?

A

Activation of Mu opioid receptors in the midbrain can lead to the substantia nigra releasing lots of dopamine which leads to addiction q

25
Q

What are opiates?

What are some examples?

A

The natural substances of opioids

Codeine
Morphine
Diacetyl morphine (heroin)

26
Q

What are some synthetic opioids?

A

Methadone
Fentanyl

27
Q

What does codeine get metabolised into?

What does this metabolism?

A

Morphine
CYP2D6

28
Q

What is the simple way by which opioids cause pain relief?

A

Activating Mu opioid receptors inhibit Ca2+ influx into neurones decreasing the release of excitatory neurotransmitters (GLUTAMATE) to the second order neurone so inhibts pain signal transmission

29
Q

What are therapeutic opioids used for?

A

Analgesia (euphoria)
Antitussive (cough suppression)
Dyspnoea
Anaesthetic
Anti diarrhoeal (since side effect is constipation)
Palliation (symptom relief not underlying cause treatment)

30
Q

What are some examples of therapeutic opioids?

A

Codeine
Morphine
Fentanyl
Buprenorphine
Tramadol

31
Q

What is the lipid solubility, onset time and duration time of morphine?

A

Lower lipid solubility
Slower onset
Relatively long duration

32
Q

What is the lipid solubility, onset time and duration time of fentanyl?

A

Highly lipid soluble
Fast onset

Short duration of action

100x POTENCY OF MORPHINE

33
Q

What type of drug is codeine?

A

Prodrug converted to morphine (secondary metabolite) by CYP2D6

34
Q

How is codeine administerd?

A

Oral
Subcutaneous

35
Q

How is morphine adminstered?

A

Oral
IV
IM
Subcutaneous (SC)
rectally

36
Q

How is fentanyl administered?

A

Transdermal
Intra nasal
IV
Epidural

37
Q

Go to slide 2 and label the pain altering pathways:

A
38
Q

What drugs are given for mild pain?

A

Paracetamol
Ibuprofen

39
Q

What drug is given for mild to moderate pain?

A

Codeine

40
Q

What drug is given for moderate to severe pain?

A

Morphine
Fentanyl

41
Q

Label slide 6

A
42
Q

What is the problem with compound analgesics like co-codamol?

A

Cant change dose of one of the drugs in the preparation very well

43
Q

What are some adverse drug reactions of Opioids?

A

Constipation
Drowsiness
Dysphoria
Euphoria
Flushing
Headache
MIOSIS (pupillary constriction)
Respiratory depression
Itching

44
Q

Why do you get itching with opioids?

A

Leads to histamine release

45
Q

What are the contraindications to opioids?

A

Comatosed patients
Head injuries or raised ICP
Resp depression
Paralytic ilium
Asthmatics (histamine)
Pregnancy

46
Q

What ae some drug drug interactions with opioids?

A

CNS depressants (antiepilieptics and benzodiazepines)
Opioids
Drugs reducing gut motility
CYP450 inducing or inhibiting enzymes

47
Q

What is buprenorphine?

What is it used for?

A

Partial opioid receptor agonist with long action

Can be given to addicts to provide small high and not got resp depression

48
Q

What is Naloxone?

What is it used for?

A

Mu opioid receptor competitive antagonist

Used in overdose as it rapidly distributes and doses not last long

49
Q

What is methadone?

A

Very lipophilic opioid (more lipophilic than morphine nad has. A longer duration of action

50
Q

Why may Naloxone be amidnstered multiple times in respiratory depression?

A

It may wear off then the opioid can cause respiratory depression

51
Q

Go to slide 10 and match the analgesic repsonse graph tot the opioid agonist or antagonist:

A
52
Q

What is the idea that leads to development of tolerance with opioid use?

A

More cAMP is made so base levels are higher since body is anticipating th opioid to reduce the cAMP levels

Receptor internalising and uncoupllling

53
Q

What causes the withdrawal symptoms of opioid use?

A

The increased base levels of cAMP levels without opioids inhibiting it leads to excess of normal function (tachycaradai, tachypnoea etc..)

Opioids inhibit the levels of cAMP when given

54
Q

What are some symptoms of opioid withdrawal?

A

Insomnia
Anxiety
Excessive sweating
Enlarged pupils
Tachycardia
Tachypnoae
Diarrhoea

55
Q

What are the 3 classes of controlled drug?

A

Class A
Class B
Class C

56
Q

How are controlled drugs assigned to a class?

A

A is the most harmful when misused

57
Q

What are some Class A drugs?

A

LSD
Fentanyl

58
Q

Hat are some Class B drugs?

A

Codeine
Ketamine

59
Q

What is a Class C drug?

A

Anabolic steroid