Analgesics in MOS 3 Flashcards

1
Q

What is the NNT for 60 mg of codeine?

A

16.7

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2
Q

What is the NNT of 60mg codeine in combination with 1g of paracetamol?

A

2.2 (1.8-2.9)

hence it has a higher efficacy

based on data from 197 patients

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3
Q

Opioids are effective for what kinds of pain following oral surgery?

A

moderate to severe pain

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4
Q

What are some side effects of opioids?

A
  • nausea
  • vomiting
  • constipation
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5
Q

The WHO pain ladder was originally applied to the management of ____ pain. However, it is now applied to the management of all types of pain

A

cancer

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6
Q

Give examples of mild opioid drugs

A

codeine phosphate dihydrocodeine

tramadol

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7
Q

Give an example of a stronger opioid drug

A

morphine

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8
Q

What is an opioid?

A

this is a compound that has pharamacologucal activity at an opioid receptor. It may be endogenous or administered, naturally occuring or synthetic

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9
Q

What is an opiate?

A

this term is strictly reserved to describe alkaloids that are derived naturally from the opiate poppy (papaver somniferum)

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10
Q

What is the UK definition of a narcotic?

A

an addictive drug affecting mood or behaviour

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11
Q

What is the USA definition of a narcotic?

A

narcotic refers to opioids for medicinal use as well as illegally used opium derivatives

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12
Q

What is opium?

A

an extract of the juice of the poppy which has been used for social and medicinal purposes for thousands of years as an agent to produce analgesia, euphoria and sleep

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13
Q

What is the most abundant opiate found in opium?

A

morphine

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14
Q

Give examples of synthetic compounds that have been produced by chemical modification of morphine

A
  • codeine
  • diamorphine
  • pethidine
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15
Q
A
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15
Q

How do opioids differ from one another?

A
  • relative efficacy
  • pharmakokinetics (body does to the drug)
  • other actions
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16
Q

How can the effects of opioids be reversed ?

A

opioid antagonist such as naloxone

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17
Q

How have opioids been traditionally classified?

A
  • weak
  • intermediate
  • strong
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18
Q

What adverse side effect does high dose codeine cause?

A

respiratory depression

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19
Q

What are the 3 principal classes of opioid receptors?

A
  • u- mu
  • kappa
  • delta
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20
Q

Opioids produce majority of their therapeutic and adverse effects by acting as agonists at ____ receptors

A
  • u- mu receptors
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21
Q

Endogenous opioids do not cause any side effects. True or false

A

true

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22
Q

Opioids also exhibit a ceiling effect similar to non-opioid analgesics. True or false

A

False
the analgesic response to the opioids acting on the u-receptors continues to increase with increasing dose

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23
Q

What is the recommended analgesic regime for mild pain following a forceps extraction?

A

paracetamol 1g every 6 hours regularly (maximum fo 4g/24 hours)

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24
Q

What is the recommended analgesic regime for moderate pain following surgical removal of a tooth?

A

ibuprofen 400mg every 6 hours
(maximum 2.4g/24 h) and paracetamol 1g every 6 hours as necessary

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25
Q

What is the recommended analgesic regime for severe pain following surgical removal of a tooth involving bone removal ?

A

ibuprofen 400mg every 6 hours regularly (maximum 2.4g/24hours) and paracetamol 1g/codeine 60 mg combination every 6hours regularly

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26
Q

Opioids are often localised in high concentrations in highly perfused tissues. Give examples of such tissues

A
  • lungs
  • liver
  • kidneys
  • spleen
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27
Q

What is the most common route of administration of opioid analgesics ?

A

orally

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28
Q

________ preparations of opioids are more rapdily absorbed than solid preparations

A

liquid

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29
Q

Why might the oral dose of opioids required to provide sufficient analgesic relief be higher than the dose required if it were administered parenterally?

A

this is due to significant first pass metabolism by glucoronidation in the liver

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30
Q

IM injections of opioids can be administered. Give examples of muscles most often used

A
  • deltoids
  • vastus lateralis muscles
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31
Q

Why are IM opioid injections not ideal?

A
  • painful
  • not acceptable to some patients
  • variable absorption
    *
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32
Q

Why must IV administration of opioids be done slowly?

A

to minimise adverse effects

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33
Q

What are the key requirements for IV administration of opioids?

A
  • skilled nursing
  • pharmacy support
  • infusion pump for continuous or patient controlled administration
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34
Q

What opioid is available via a transdermal drug delivery system ?

A

fentanyl

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35
Q

Why are transdermal opioids contraindicated for use in acute post-operative pain?

A

this is because they are slow release

high incidene of side effects

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36
Q

What drug is the gold standard for acute pain management?

A

morphine

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37
Q

What does PCA refer to?

A

patient controlled analgesia
- use of a device (programmable pump) for self administration of small doses of opioids intravenously

38
Q

What side effect of opioids is most commonly observed in PCA when compared to other conventional routes of administration?

A

itching

39
Q

What is the NNT of a single oral dose of 30mg of dihydrocodeine? What is the consequence of this?

A

8.1

does not provide effective analgesia for acute post operative pain

40
Q

What is the NNT of 400mg of ibuprofen?

A

2.5 (2.4-2.7)
(this data is based on a cochrane systematic review involving only 3 trials)

41
Q

A single dose of tramadol is equivalent to …

A

1000 mg of paracetamol

42
Q

What is the NNT of 100mg dose of tramadol ?

A

4.6 (3.6-6.4)

43
Q

What adverse side effects have been reported following use of tramadol in dental extraction trials?

A
  • vomiting
  • nausea
  • dizziness
44
Q

What is the postulated mechanism for opioid induced side effects such as nausea and vomiting?

A

stimulation of opioid receptors within the chemoreceptor trigger zone in the postrema of the medulla

45
Q

What is the effect of opioids on the GI system?

A
  • delayed gastric emptying
  • altered intestinal tone (increased)
  • altered intestinal motility - propulsive contractions reduced

This results in constipation

46
Q

How can the GI effects of opioids be managed in patients on short term therapy?

A
  • pts counselled to take water and fibre
  • laxative can also be prescribed
47
Q

Why is morphine contraindicated for patients having day-case surgery?

A

potential for nausea and vomiting

48
Q

________ can be used to counteract itching side effect of opioid use.

A

antihistamines

non-sedating antihistamines are preferable here to avoid increasing opioid induced drowsiness

49
Q

Certain opioids, such as ____, can be more sedative than others.

A

morphine

50
Q

What is the effect of morphine and other mu/kappa agonists on the eyes?

A

pupil constriction

due to excitatory action in parasympatheric nerve innervations

51
Q

What is the result of opioid inhibition of brainstem respiratory centres?

A
  • reduced respiratory rate
  • reduced tidal volume
52
Q

Briefly state what respiratory depression is

A

this is where there is a reduced response to carbondioxide

53
Q

________ hypotension is an adverse effect of opioid use.

A

postural

54
Q

How can opioid overdoses be managed

A

naloxone

55
Q

What is naloxone ?

A

u-opioid receptor competitive antagonist

blocks u-receptors and produces rapid reversal of symptoms

56
Q

Diamorphine is commonly medically used in the USA and other European countries. True or false

A

False

never used in USA and some other European countries

57
Q

Briefly describe the affinity of codeine with opioid receptors

A

codeine has low affinity for opioid receptors

58
Q

State another name for morphine

A

3 methyl morphine

59
Q

What is responsible for the analgesic effects of codeine ?

A

10% of codeine is coverted following demethylation with the CYP2D6 enzyme. This produces morphine which is responsible fot the analgesic effect.

60
Q

What is the bioavailability of codeine?

A

50%

61
Q

What is the bioavailability of morphine?

A

25%

62
Q

What is the bioavailability of tramadol?

A

75%

63
Q

Give examples of medications that are able to block the demethylation of codeine into morphine

A
  • SSRI- selective serotonin reuptake inhibitors
  • some antihistamines e.g. diphenhydramine
64
Q

What are the available codeine/paracetamol combinations available in the UK?

A
  • 30/500 (30mg of codeine phosphate, 500mg of paracetamol) - high strength

lower stregth combinations
* 8/500
* 12.8/500

65
Q

Aside from pain management, what are some other uses of codeine?

A
  • anti-tussive (stop coughing)
  • anti-diarrhoeal
66
Q

What is the adult dose of orally administred codeine?

A

30-60mg every 4 hours for a maximum of 240mg daily

67
Q

What is the IM dose of codeine?

A

30-60 mg every 4 hours

68
Q

What is the half life of dihydrocodeine?

A

4 hours

69
Q

What is the oral dose of dihydrocodeine?

A

30 mg every 4-6 hours

70
Q

What is the oral dose of dihydrocodeine for children >4years old?

A

0.5-1mg/kg evert 4-6 hours

71
Q

What is the subcutaneous/IM dose of dihydrocodeine for adults?

A

50mg every 4-6 hours

72
Q

What is the subcutaneous/IM dose of dihydrocodeine for children >4 years old ?

A

0.5-1mg/kg every 4-6 hours

73
Q

What is the MOA of tramadol?

A
  • selective u-receptor agonist
  • weak inhibitor of the reuptake of noradrenaline and serotonin (resembles the action of TCAs)
74
Q
A
74
Q

Tramadol potentiates descending inhibitory pathways. What is the benefit of this?

A

this action has been shown to have efficacy in the management of chronic pain

74
Q

Why is tramadol not a controlled drug in many countries?

A

this is because is has low potential for abuse and addiction

75
Q

What is the half life of tramadol?

A

7 hours

76
Q

What is the oral dose of tramadol for adults and children >12 years ?

A

50-100mg not more often than every 4 hours

77
Q

What is the IM/IV dose of tramadol for adults and children over 12 years old?

A

50-100mg every 4-6 hours

78
Q

Why is morphine most commonly give via IV or IM injection?

A

absorption of morphine by mouth is variable

79
Q

What is the half life of morphine?

A

2-3 hours

80
Q

What is the main mode of inactivation of morphine ?

A

hepatic metabolism

metabolites are then excreted in the urine

(this is the same for most other opioids)

81
Q

PCA is most commonly used for ________ .

A

morphine

82
Q

What is the IM/subcutaneous dose of morphine?

A

10mg initially every 4 hours

(5mg in elderly/frail)

83
Q

What is another name for diamorphine?

A

heroin

84
Q

What is diamorphine?

A

semi-synthetic opioid with no activity at the u(mu) receptor

85
Q

Diamorphine is used medically in …

A

the UK

86
Q

The use of tramadol is not recommended for children under 12 years old. True or false

A

True

87
Q

What is the recommended dose of morphine for 12-18 year olds ?

A

2.5-10mg every 4 hours

88
Q

Opioids should be avoided in…

A

Pregnant patients or those who are breastfeeding

89
Q

Opioids should be used with caution in …

A
  • patients with impaired respiratory function
  • avoided in COPD patients
  • avoided in parients presenting with head injury before full neurological investigation
  • hypotension
  • urethral stenosis
  • myasthenia gravia
  • prostatic hypertrophy
  • obstructive and inflammatory bowel disorders
  • disease of biliary tract
  • convulsive disorders
90
Q

When is a reduced opioid dose recommended?

A
  • elderly patients
  • hypothyroidism
  • adrenocortical insufficiency
91
Q

What clinical scenarios require a reduction in opioid doses?

A

patients with hepatic or renal impairements

they should be reduced or avoided entirely