Oral Surgery - Analgesia Flashcards
What is the mechanism of action of aspirin?
It inhibits cycle-oxygenase, reduces the production of prostaglandins
What cyclo-oxygenase is aspirin more effective at inhibiting and what is the effect of this?
COX1
This reduces platelet aggregation
Predisposes to damage of gastric mucosa
What is the analgesic affect of aspirin
The peripheral action is predominate, it reduces prostaglandin synthesis in inflamed tissues
Reducing pain
What is the anti-pyretic affect of aspirin
It prevents the temperature rising affects of interleukin-1 and the rise in brain prostaglandin levels
It reduces the elevated temperature in fever
What is the third affect of aspirin, analgesic, anti-pyretic and ….
Anti inflammatory
Will reduce redness and swelling Aswell as pain a the site of the injury
What three affects do prostaglandins have on the gastric intestinal mucosa
Inhibit gastric acid secretion
Increase blood flow through the gastric mucosa
Help production of mucins by cells in the stomach lining
What is the function of gastric mucins
Gastric mucins are components that protect the gastric epithelium from the itch concentrations of Acid in the stomach lumen and from auto digestion by pepsin
What are three symptoms a patient may experience following an aspirin overdose
Hyperventilation
Deafness
Vasodilation and sweating
What component of aspirin causes the mucosal burn and why does this happen.
Aspirin applied to locally to the oral mucosa results in a chemical burn, this is a direct result of the salicylic acid.
Aspirin has no topica affect
Why should aspirin not b given to someone taking warfarin/ anticoagulants
Aspirin enhances warfarin and other anticoagulants
Displaces warfarin from binding sites on plasma proteins, increases the free warfarin.
The majority of warfarin is bound( inactive). If more is realised this will become active increasing bleeding tendency.
What are thee complications that taking aspirin during pregnancy?
Increased risk of haemorrhage
Increased risk of jaundice in the baby
Can potentially prolong Labour
Where is aspirin metabolised and where is it excreted
Aspirin is metabolised in the liver and excreted by the kidney
Where are PGE2 and PGI1 synthesised
PGE2 - Renal medulla
PG1 - glomerulus
What are three affects of inhibition of renal prostaglandins
Sodium retention
Reduced renal blood flow
Renal failure
Aspirin is contraindicated in children under 16s years and breastfeeding, what condition is this aiming to prevent
Reyes Sydrome
Fatty degerative process in the liver and profound encephalopathy in the brain
What is the best way to find out if someone with asthma can take NSAIDS
Ask the patient if they have any hypersensitivity to NSAIDs before or if they have any adverse affects when taking them before
Why are elderly people in the list of groups to avoid when prescribing NSAIDS
They have a smaller blood volume, they tend to be on other medications and often have other medical issues
Elderly people are most susceptible to drugs induced side affects in general
What is G6PD deficiecy and what does it make them susceptible to
Glucose 6-phosphonate deficiency - they are at risk of developing acute haemolytic anamia
Where is G6PD most popular
Most common in individuals orgingating from parts of Asia.Africa/ oceana and southern Europe’s
What are the 4 groups that NSAIDS are completely contraidnacted in?
Children under 16years; breastfeeding
Previous or active peptic ulceration
Haemophilia
Hypersensitivity to aspirin or any other NSAID
When prescribing aspirin for mild to moderate odontogenic what is the dosage
300mg 2 tablets 4 times a day
What is the maximum dosage of aspirin
4grams
If a patient has a hypersensitivity to aspirin or any other NSAID what can be prescribed, what groups would you be wary of when prescribing these?
Lansoprazole 15mg 1 capsule 1 daily
Gastro-resistant omeprazole 20mg 1 capsule 1 daily
Be wary of patients with liver diease, pregnancy or breast feeding
What is the maximum adult dose for ibuprofen
2.4 grams
What is the prescription for ibuprofen
Tablets 400mg
1 tablet 4x daily
Name 4 cautions when prescribing ibuprofen
Previous or active peptic ulcer diease
The elderly
Pregnancy and lactation
Renal, cardiac or hepatic impairment
What is indicated if more than 400mg has been injested within the preceding hour
Activated charcoal followed by symptomatic measures
What is the daily max dose of paracetamol
4g daily
8 tablets
What is the mode of action of paracetamols
Hydroperoxides are generated from the mechanism of the arachidonic acid by COX and activate a positive feedback to stimulate cox activity.
This feedback is blocked by paracetamol thus directly inhibiting COX
Why is there little/no gastric mucosal irritation when suing paracetamol?
This is because it does not seem to have much affect on peripheral prostaglandins, is is described as a safe analgesic
What is the main site of action of paracetamol
The thalamus
What amount of paracetamol can cause a potential overdose and what are the effects?
As little as 10-15grams (20-30 tablets) or 150mg/kg of paracetamol a taken wihtin 24 hours can cause severe hepato-cellular necrosis and less free frequently renal tubular necrosis
Why, even if there is a lack of signficant symptoms should a patient who has taken a paracetamol overdose go to hospital immediately
Liver damage is at its maximum 3-4 days after the injection, therefore even if there are a lack of symptoms they should be transferred to hospital
What are the three groups we should have caution when prescribing?
Hepatic impairment
Renal impairment
Alcohol dependable
Disuss the pathway of pain
Trauma and infection lead to the breakdown of membrane phospholipid producing arachiodonic acid.
This arachiodonic acid can then be broken down to produce prostaglandins.
Prostaglandins sensitise the tissues too other inflammatory products with results in pain
What is the effect of prostaglandins
Prostaglandins themselves do not cause pain directly, they sensitise the tissues to other inflammatory products such as leukotrines
Name three clinical features of trigeminal neuralgia
Severe spasm of pain; electric shock; lasts a few seconds
Usually unilateral
Older age group
Periods of remission, recurrence often greater severity
What is the starting dose of carbamazepine and how does the treatment progress
Stating dose is usually 100/200mg tablets depending on the patient and then the dose is gradually increased according to responses
Usuall dose is 200mg 3-4 daily
Where do opioids act
They act on the spinal cord, mainly in the dorsal horn pathways, central regulation of pain
How do opioids work
They produce their effects via specific receptors which are closely associated with neuronal pathway as that transmit pain to the CNS.
What are the three main problems with opioids
Dependence - psychological and physical. Withdrawal will lead to cravings and the patient will become not well
Tolerance - to achieve the same therapeutic affect the dose of the drug needs to be progressively increased
Effects on smooth muscle - constipation and urinary and bowel retention
What affect does alcohol have on opiods
It enhances their affect
When the opioid has its effect on the CNS it depresses 4 things;
- Pain centre - alters awareness and perception of pain
- Higher centres
- Respiratory centre
- Cough centre
What the most common side affects of opioids and what are the side affects of a larger dose
Common - Nausea, vomiting and drowsiness
Larger doses can lead to respiratory depression and hypotension
What are the three groups which are contraindicated when using opioids?
Acute respiratory depression
Acute alcoholism
Raised intracranial pressure/ head injury
Why must you never give someone with raised intracranial pressure or a suspected head injury an opioid?
This interferes with respiration and it affects pupillary responses which are vital for a neurological assessment
What is the composition of paracetamol and codeine in co-codamol
8mg codeine and 500mg of paracetamol
What is the only codeine combination that is on the dental list
Dihydrocodeine
Dentists can only prescribe dihydrocodeine in the oral route, what is the dosage
30mg tablets 4-6 hours
What are the two serious interactions with dihydrocodeine?
Antidepressants MAOIs ( monoamine oxidase inhibitors)
Dopaminergics
What is the BNFs stance on opioid use in dentistry and why
Due to the side affects of nausea and vomiting it is of little value for dental pain
It is not very effective for post operative pain
What is the antidote for an opioid overdose and when is it indicated
The specific antidote is naloxone and it is indicated when there is a coma or bradypneoa
Why must naloxone be monitored and repeated injections
Because it has a shorter duration of action than many opiods
