Opioid Pharmacology

Question 1

How is 50% of oral morphine metabolised

Answer 1

First pass metabolism in the liver

Question 2

What does 50% metabolism of morphine mean for prescription

Answer 2

We have to double the dose (10mg morphine = 5mg really)

Question 3

How long does a single dose of morphine last

Answer 3

3-4 hours

Question 4

How often is morphine given for ‘slow release’ palliative care

Answer 4

Twice a day

Question 5

Benefits of diamorphine vs morphone

Answer 5

Diamorphine is more potent and passes across blood-brain barrier more quickly

Question 6

What class are opioids categorised as

Answer 6

Class A drugs

Question 7

Why are opioids difficult to get a hold of

Answer 7

1. Secure storage

2. CD (controlled drug) books need two signatures

Question 8

Dihydrocodeine vs codeine

Answer 8

1.5 x more powerful

Question 9

How do opioids work physiologically

Answer 9

1. Inhibits release of pain transmitters at spinal cord and midbrain by binding to G-coupled receptors
2. Modulate pain perception at higher centres and emotional response

Question 10

What two hormones do opioids inhibit to bring bout decreased pain perception

Answer 10

Natural endorphins

Enkephalins

Question 11

How do Opioids work

Answer 11

Descending inhibition of pain

Question 12

Do opioids bring about sustained activation

Answer 12

No

Question 13

What is the problem of sustained activation due to opioids

Answer 13

Leads to tolerance and addiction

Question 14

Name of the four receptors

Answer 14

MOP
KOP
DOP
NOP

Question 15

What do Kappa morphine receptors do which is different to the other three

Answer 15

Causes depression instead of euphoria

Question 16

What receptor do all drugs currently act on

Answer 16

M(u) receptors

Question 17

Define Potency

Answer 17

How well the drug binds to the receptor

Question 18

Define efficacy

Answer 18

How well receptor is activated

Question 19

Which is more potent, Morphine or Diamorphine

Answer 19

Morphine (10mg) vs Diamorphine (5mg for same effect)

Question 20

Why does Tolerance occur

Answer 20

Down-regulation of receptors with prolonged use

Need higher doses to reach same effect

Question 21

Define dependance

Answer 21

Psychological response to tolerance - craving

Question 22

When does opioid withdrawal take place

Answer 22

24 hours and lasts 72 hours

Question 23

Where else can opioid receptors be found other than the pain system

Answer 23

1. Digestive tract

2. Respiratory control centre

Question 24

Side effects of opioids

Answer 24

1. Sedation
2. Nausea
3. Constipation
4. Itching
5. Immune Suppression
6. Endocrine Effects

Question 25

Why do we start with a small dose of opioids and titrate up

Answer 25

Because different patients have a range of sensitivity to opioids

Question 26

How do we treat Opioid induced respiratory depression

Answer 26

ABC | Naxolone IV via titration (remember patient sensitivity)

Question 27

What do we have to be aware of when giving Naxolone to drug addicts in A&E

Answer 27

Short half-life of naxolone

Question 28

Ho do we titrate Naxolone

Answer 28

Dilute 1ml in 10 ml of saline

Question 29

What is the issue with opioid use in Chronic non-cancer pain

Answer 29

They are losing effectiveness quickly More deaths than US traffic accidents and firearms

Question 30

What is the results of opioid addiction on patient

Answer 30

Easy to start and difficult to get them off it

Question 31

What kind of drug is codeine

Answer 31

Prodrug

Question 32

What enzyme metabolises Codeine

Answer 32

CYP2D6

Question 33

How doe genetics effect Codeine metabolism

Answer 33

CYP2D6 activity is decreased in 10-25% of white population and absent in a further 10% so codeine has a reduced effect in this population CYP2D6 is overactive in 5% of whites so increased risk of respiratory depression

Question 34

What is Morphine metabolised to

Answer 34

morphine-6-glucuronide

Question 35

How is Morphine-6-Glucuronide excreted

Answer 35

Kidneys

Question 36

Potency of morphine-6-glucuronide vs morphine

Answer 36

Morphine is less potent

Question 37

How do we give morphine to patients with 30%< renal function

Answer 37

Reduce dose and timing interval OR use oxycodone instead as it is safer

Question 38

What is Tramadol

Answer 38

Weak opioid agonist

Question 39

Potency of TRamadol vs Codeine

Answer 39

Stronger in Tramadol

Question 40

What type of drug is Codeine and what metabolises it

Answer 40

Prodrug Metabolised by CYP2D6

Question 41

End-product of Tramadol metabolism

Answer 41

O-desmethyl tramadol

Question 42

Secondary effect of Tramadol

Answer 42

In analgesia (serotonin and nor-adrenaline reuptake inhibitor)

Question 43

What and why do we take care with Tramadol prescription to people with antidepressants

Answer 43

Interacts with SSRIs, antidepressants and MAOs fatally

Question 44

How much of the population can't metabolise morphine

Answer 44

10%

Question 45

What is diamorphine also known as

Answer 45

Heroin

Question 46

Three synthetic opioids

Answer 46

Pethidine Fentanyl (potent) Alfentanil (potent)

Question 47

What happens if we overdose on Buprenorphine

Answer 47

No respiratory depression

Question 48

Fastest mode of administration of opioids

Answer 48

IV takes 1 minute to travel round the whole body

Question 49

How long does it take for morphine to reach the brain

Answer 49

5 minutes

Question 50

How is does self-administered by patients with analgesia

Answer 50

Every 5 minutes with lockout

Question 51

Why is salt-administration for analgesia safe

Answer 51

Patient will sleep before onset of respiratory depression

Question 52

How long do opioids have an effect for

Answer 52

30 minutes

Question 53

Potency of Pethidine vs Morphine

Answer 53

10 times weaker

Question 54

Why does Buprenorphine only reach 50% response rates

Answer 54

Only a partial agonist (safer)

Question 55

How does mixing Morphine with Naloxone effect efficacy of morphine

Answer 55

Reduces it

Question 56

Why do we mix morphine and Naloxone

Answer 56

To correct an overdose

Question 57

How does continued morphine use effect Mu receptors

Answer 57

Desensitises them