Analgesia

Question 1

Describe the pain pathway.

Answer 1

Tissue injury causes injury to the phospholipid cell membrane, causes release of arachidonic acid.
COX-1 and COX-2 are produced which causes production of prostaglandin.
Prostaglandin sensitises the tissues to make them more susceptible to feeling the pain.
5-lipoxygenas pathway also activated- produces leukotrienes- causes pain and inflammation.

Question 2

What is aspirin?

Answer 2

NSAID- has analgesia, anti-inflammatory and antipyretic effects.

Question 3

What is the mechanism of action of Aspirin?

Answer 3

Inhibits COX-1 and COX3- so prostaglandin production is decrease.

Question 4

Why are people more at risk of bleeding if they take aspirin?

Answer 4

COX-1 is invovled in platelet aggregation.

Question 5

What are the adverse effects of aspirin?

Answer 5

GIT problems- prostaglandins usually inhibit acid secretion in the stomach and increase blood flow through the gastric mucosa- this would be inhibited in aspirin.

Hypersensitivity- rashes, angiooedema, acute bronchospasm

Overdose

Mucosal burns- direct effect of salicylic acid
- Aspirin must be taken with water.

Question 6

What groups of people should not take aspirin?

Answer 6

Peptic ulceration
Epigastric pain
Bleeding abnormalities
Anti-coagulants- enhances effect of warfarin
Pregnancy/breast feeding- risk of haemorrhage, may cause Reye’s syndrome in breast feeding.
Patients on steroids- because of peptic ulcer risk
Renal/hepatic impairment
Children and adolescents under 16 years old- because of the risk of Reye’s syndrome.
Asthma
Hypersensitivity to NSAIDs
Taking other NSAIDs
Elderly
G6PD-deficiency

Question 7

What is Reye’s syndrome?

Answer 7

Fatty degenerative process in lover and profound swelling in the brain.

Encephalopathy
Liver damage

Question 8

Which of these groups is aspirin completely contraindicated in?

Answer 8

Children and adolescents under 16 years of age
Breastfeeding
Previous or active peptic ulceration
Haemophillia
Hypersensitivity to aspirin

Question 9

What dose of aspirin should be prescribed?

Answer 9

300mg, 40 tablets, 2 tablets 4 times a day for 5 days after food.

Question 10

If paracetamol is not working and someone with a history of peptic ulceration requires an NSAID. What would you prescribe them?

Answer 10

Proton pump inhibitor.

Lansoprazole- 15mg, 1 capsule ones a day for 5 days.

Question 11

What is Ibuprofen?

Answer 11

NSAID

Less effects on platelets than aspirin but still can be irritant to the gastric mucosa.

May cause broncho-spasm.

Question 12

What is the recommended drug regime for Ibuprofen?

Answer 12

400mg tablets, 1 tablet four times a day for 5 days.
- Taken after food.

Question 13

WHat is the maximum adult dose of Ibuprofen?

Answer 13

2.4mg in 24 hours.

Question 14

In what groups of patients should you be cautious with prescribing Ibuprofen?

Answer 14

Asthmatics
Gastric irritation
Peptic ulceration
Previous sensitivity to NSAIDs
Elderly
Pregnant and lactation
Renal, cardia or hepatic impairment
Patients taking other NSAIDs
Patients on long term steroids.

Question 15

What are the potential side effects of Ibuprofen?

Answer 15

GIT discomfort- bleeding and ulceration

Hypersensitivity reactions

Headache, dizziness, drowsiness, fluid retention, renal impairment, hepatic damage.

Question 16

What are some of the potential drug interactions with Ibuprofen?

Answer 16

ACE inhibitors
Anticoagulants
Antidepressants
Corticosteroids
Beta-blockets
Calcium-channel blockers
Lithium
Tacrolimus

Question 17

What is the mode of action of paracetamol?

Answer 17

Inhibits the positive feedback of COX by hydroperoxides.
- thus indirectly inhibiting COX.

Question 18

What are the effects of paracetamol (in general terms)?

Answer 18

Analgesic
Antipyretic

Little or no anti-inflammatory action
No effects on bleeding time
Does not interact significantly with Warfarin
Less irritant to GIT
Suitable for children

Question 19

In which patients should you be cautious of prescribing paracetamol to?

Answer 19

Hepatic impairment
Renal impairment
Alcohol dependence

Question 20

What are the side effects of paracetamol?

Answer 20

Rashes

Blood disorders

Hypotension reported on infusion

Liver damage

Question 21

What is the recommended dosage of paracetamol?

Answer 21

500mg tablets, 2 tablets 4 times a day for 5 days.
- leave 4 hours in between doses

Question 22

What is the maximum daily dose of paracetamol for an adult?

Answer 22

4g in 24 hours.

Always advise patients of the maximum daily dose and remind them that they do not exceed that.

Question 23

What medication must you check first before you advise someone to take paracetamol?

Answer 23

Co-codamol
- Has paracetamol in it.

Anadin
Lemsip

Question 24

What are opioid analgesics?

Answer 24

Act in the spinal cord- in the dorsal horn pathways.
- central regulation of pain.

Question 25

What are some of the problems with opioids?

Answer 25

Dependence- withdrawal of the drug can lead to psychological cravings and the patient will become physically ill.

Tolerance- to achieve the same therapeutic effects the dose of the drug needs to be progressively increased.

Constipation

Urinary and bile retention

Question 26

What are the CNS effects of opioid analgesics?

Answer 26

Respiratory depression
Cough centre
Pain centre- alters awareness/perception of pain

Question 27

What are the potential side effects of opioids?

Answer 27

Nausea
Vomiting
Drowsiness
Headache
Bradycardia
Hallucinations
Dependence
Tolerance

Question 28

What conditions are contraindicated to prescribe opioids?

Answer 28

Acute respiratory depression

Acute alcoholism

Raised intracranial pressure/head injury

Question 29

What opioid analgesic can dentists prescribe?

Answer 29

Dihydrocodeine- 30mg every 4-6 hours as necessary