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Flashcards in Pain Deck (23):
1

What is the purpose of acute pain?

1. Warning of tissue damage
2. Immobilisation for healing
3. Protection of species

2

What physiological effects does pain cause?

Increased HR, BP, RR and decreased GIT

3

What are the 3 classifications of pain? (nerve-related)

1. Nociceptive (chemicals in body stimulate nerve)
2. Neuropathic (direct damage or disease of nerve)
3. Mixed (most)

4

What are the 2 types of pain, and what are their subdivisions?

1. Acute (less than 7 days) either post-operative or non-surgical cause
2. Chronic - either cancer pain or non cancer pain

5

What are the two types of nerve fibres that transmit pain, and what kind of pain do they cause?

1. C afferent fibres - smallest, unmyelinated - cause dull, intense, slow-onset pain
2. Aδ fibres - small, myelinated - cause sharp immediate onset pain

6

Name two places in the body that do not contain nociceptors?

Brain, liver

7

What is the bioavailability of morphine administered orally?

50 %

8

How long does a single dose of morphine last?

3-4 hours

9

In what form can morphine be administered trans-dermally?

Through fentanyl patches

10

Name one partial agonist and one antagonist of morphine

Partial agonist = Buprenorphine
Antagonist = Naloxone

11

How do opioids work?

Opioids bind to opioid receptors in the brain (G protein coupled receptors) and then inhibit the release of pain transmitters at the spinal cord and midbrain. Descending inhibition of pain.

12

What was the first opioid receptor identified?

µ - receptor (MOP)

13

Why aren't kappa agonists used?

Caused depression rather than euphoria

14

What is potency?

Whether a drug is 'strong' or 'weak' relating to how well the drug binds to a receptor

15

What is efficacy? And what does it relate to?

Maximal response or not? Depends whether is a full or partial agonist

16

What is tolerance?

Down regulation of receptors with prolonged use. Need of higher doses to achieve same effect

17

What is dependence?

Psychological craving

18

How long after the last opioid dose does it take for withdrawal symptoms to set in?

Within 24 hours. Will last 72 hours

19

Give 5 potential side effects of opioids

1. Respiratory depression
2. Sedation
3. Itching
4. Nausea and vomiting
5. Constipation
6. Immune suppression
7. Endocrine effects

20

How would you administer Naloxone to a heroin overdose patient and why?

Give ampule IM and then IV. Has a short half life so if they wake up and walk away, will have a reserve, so don't fall back into toxic levels

Titrate to effect - 1ml in 10 ml saline

21

Why is codeine not given to breast feeding mothers/ paeds?

Codeine is a pro-drug, it needs to be metabolised by cytochrome CYP2D6 and this enzyme is overactive in 5% of the population, so will be at increased risk of respiratory depression with codeine

22

What property does norpethidine have if it is not excreted?

Epileptogenic

23

What is tramadol and what will it interact with?

Weak opioid agonist and prodrug. Also works as a serotonin reuptake inhibitor and nor-epinephrine reuptake inhibitor. Reacts with SSRI's, tricyclic antidepressants and MAOI's