Analgesia in Denistry Flashcards
What analgesia medications are listed for use under the BNF Dental Practitioners Formulary?
- Aspirin (NSAID)
- Ibuprofen (NSAID)
- Diclofenac (NSAID)
- Paracetamol
- Dihydrocodeine (Opioid)
- Carbamazepine
What role do prostaglandins play in a patients pain?
They do not cause pain directly BUT they SENSITISE TISSUES TO OTHER INFLAMMATORY PRODUCTS such as leukotrienes
Discuss the pain pathway in terms of the production of prostaglandins:
- trauma and infections lead to breakdown of phospholipid cell membrane
- causes production of ARACHIDONIC ACID
- this is broken down to form PROSTAGLANDINS
- prostaglandins sensitise the tissues to other inflammatory products which results in pain
What type of medication is Aspirin?
NSAID analgesic
What are the properties of aspirin?
- analgesic
- antipyretic
- anti-inflammatory
What is meant when a medication is described as ‘antipyretic’?
Fever reducing
What is Aspirins mechanism of action?
Inhibits cyclo-oxygenases (COX-1 & 2)
- this REDUCES PRODUCTION OF PROSTAGLANDINS
Why can aspirin cause damage of the gastric mucosa?
- inhibits production of prostaglandins
- prostaglandins stimulate the secretion of mucus (which helps to protect the stomach lining from stomach acid)
What are the analgesic properties of aspirin?
- peripheral actions predominate (but central actions also present)
- analgesic action results from INHIBITION OF PROSTAGLANDIN SYNTHESIS in inflamed tissues (cyclo-oxygenase inhibition)
What are the antipyretic properties of aspirin?
- prevents the temperature raising effects of interleukin-1 and the rise in brain prostaglandin levels (by inhibiting COX enzymes)
- reduces elevated temperature in fever !!!
What are the anti-inflammatory properties of aspirin?
- prostaglandins are vasodilators and also affect capillary permeability
- aspirin prevents prostaglandin production
- this acts as an anti-inflammatory and will reduce redness & swelling and pain
What are some adverse effects of aspirin?
- GIT problems
- Hypersensitivity
- Overdose (tinnitus or metabolic acidosis)
- Mucosal aspirin burns
How does aspirin cause GIT problems?
prevents prostaglandin secretion and prostaglandins:
- inhibit gastric acid secretion
- increase blood flow through gastric mucosa
- help productive of mucin by cells in stomach lining
THEREFOR ASPIRIN PREVENTS ALL OF THIS AND LEADS TO GIT PROBLEMS
In which patients must care be taken when prescribing aspirin?
Patient with GIT problems
- ulcers
- gastro-oesophageal reflux
Why must care be taken when prescribing aspirin to asthmatics?
Aspirin can cause hypersensitivity and lead to
- acute bronchospasm/asthma type attacks
- skin rashes/urticaria/angioedema
What can occur if a patient overdoses on aspirin?
- hyperventilation
- tinnitus
- vasodilation & sweating
- METABOLIC ACIDOSIS***
- coma (uncommon)
Why can mucosal burns occur in patients prescribed aspirin?
- aspirin applied locally to oral mucosa results in chemical burns (patients with impaired swallowing etc)
- direct effect of salicylic acid
- aspirin has NO TOPICAL EFFECT
*ensure aspirin is taken with water
In which patient groups should aspirin prescription be avoided/caution?
- peptic ulceration
- epigastric pain
- bleeding abnormalities
- anticoagulants
- pregnancy/breastfeeding
- patients on steroids
- renal/hepatic impairment
- children/adolescents under 16
- asthma
- hypersensitivity to other NSAIDs
- elderly
- G6PD-deficiency
How does aspirin act on Warfarin/anticoagulant drugs?
Aspirin ENHANCES WARFARIN
- displaces warfarin from binding sites on plasma proteins
- increases free warfarin (the majority of warfarin is bound/inactive… if more is released this will become active and increase bleeding tendency)
Why should aspirin prescription be avoided in pregnant patients?
Should be avoided especially in 3rd trimester
- aspirin can cause impairment of platelet function
- leads to haemorrhage, jaundice in baby and can prolong/delay baby
Why is aspirin contraindicated in breastfeeding?
Can cause Reye’s syndrome
Why should aspirin be avoided in patients taking steroid medications?
Approx. 25% of long term systemic steroid patients will develop an ulcer
- aspirin may result in perforation
Why should aspirin be avoided in renal/hepatic impaired patients?
- aspirin metabolised in liver and excreted mainly in kidneys
- renal impairment = excretion may be reduced/delayed
What is Reye’s Syndrome? What can cause it?
Very rare and very serious condition in children under 16 (high mortality rate of 50%)
- fatty degenerative process in liver
- causes profound swelling in brain (causes brain damage & encephalopathy)
ASPIRIN CAN CAUSE
Why are elderly patients usually more susceptible to drug induced side effects?
- often smaller / have smaller circulating blood volume
- on other medications
- have other medical problems
What groups of patients is aspirin COMPLETELY CONTRAINDICATED IN?
- children & adolescents under 16 years; breastfeeding mothers
- previous or active peptic ulceration
- haemophilia
- hypersensitivity to aspirin or other NSAID
For mild to moderate odontogenic or inflammatory pain, what is the appropriate aspirin prescription?
Take two 300mg tablets, 4x daily after food, for 5 days
What is the maximum daily dose of aspirin?
4g
You need to prescribe aspirin to a patient with a history of previous or active peptic ulcer disease, what do you also prescribe? Give the prescription.
Proton pump inhibitor
- Lansoprazole 15mg capsules
- 1 capsule per day
- 5 days (same as aspirin)
What type of drug is Ibuprofen?
NSAID
How does Ibuprofen differ from Aspirin?
- less effects on platelets (eg not used therapeutically for this)
- lower risk of irritation to gastric mucosa
- paediatric suspension available
What is the maximum daily adult dose for Iburpofen?
2.4g
For mild to moderate odontogenic, post-op or inflammatory pain, what is an appropriate Ibuprofen regimen you might prescribe?
One 400mg tablet, 4x daily after food, for 5 days
In which patients must you be cautious when prescribing ibuprofen?
- previous or active peptic ulceration
- elderly
- pregnancy and lactation
- renal, cardiac or hepatic impairment
- history of hypersensitivity to aspirin or other NSAID
- asthma
- patient taking other NSAID
- patient on long term systemic steroid
What are some side effects that may be seen in patients taking Ibuprofen?
- GIT discomfort (occasionally bleeding & ulceration)
- hypersensitivity reactions (rashes/angioedema/bronchospasm)
- headache
- dizziness
- drowsiness
What are examples of potential drug interactions that can occur with Ibuprofen?
- ACE inhibitors
- antibiotics
- anticoagulants
- antidepressants
- corticosteroids
- diuretics
- beta blockers
- calcium channel blockers
- cyclosporin
- clopidogrel (antiplatelet)
What are the symptoms of Ibuprofen overdose?
- nausea
- vomiting
- tinnitus
If you suspect that a patient is overdosing on Ibuprofen (more than 400mg/kg in preceding hour), what should you do?
Give the patient activated charcoal
- charcoal binds to the ibuprofen preventing it from being absorbed
What can paracetamol be used for?
- analgesic
- antipyretic
How does Paracetamol differ from Aspirin or Ibuprofen?
- little or no anti-inflammatory action
- no effects on bleeding time
- less irritant to GIT
- suitable for children
What is Paracetamols mode of action?
- central nervous system main site of action
- inhibits COX by preventing positive feedback of hyperoxides (which are generated from the metabolism of arachidonic acid by COX)
Why is Paracetamol more suitable for GIT patients?
Paracetamol primarily inhibits COX-2 and has little effect on COX-1
- COX-1 is important for maintaining the protective lining of the stomach & normal function of blood clotting
In which patients should the prescription of paracetamol be cautioned?
- hepatic impairment
- renal impairment
- alcohol dependence
What are the side effects of taking paracetamol?
Side effects RARE
- rashes
- blood disorders
- hypotension
- liver damage following overdose
What drugs interact with paracetamol?
- anticoagulants (prolonged use of paracetamol possibly enhances anticoagulant effects)
- cytotoxics
- domperidone
- lipid-regulating drugs
- metoclopramide
What would the prescription of Paracetamol for pain be in adults?
2x tablets, 4x daily (4-6 hours), for 5 days
What is the maximum daily dose of paracetamol in patients?
4g
Why must you always warn patients of the daily maximum dose of Paracetamol?
10-15g (20-30 tablets) or 150mg/kg*** of paracetamol taken within 24 hours can cause severe:
- hepatocellular necrosis
- renal tubular necrosis (less frequent)
When is liver damage from paracetamol overdose at its maximum point?
3-4 days AFTER ingestion
- leads to liver failure and DEATH
How do opioid analgesics work?
Act in the spinal cord
- especially in dorsal horn pathways
- central regulation of pain
What long-term problems are associated with prescription of opioid medications?
- Dependency (withdrawal of drug will lead to psychological cravings and physical illness)
- Tolerance (dose needs to be progressively increased)
Opioids affect smooth muscle, what can this cause in patients?
- constipation
- urinary and bile retention
What are the side effects of opioids?
- nausea/vomiting/drowsiness
- dry mouth
- sweating
- headache
- bradycardia
- rashes
- palpitations
- mood changes
What can cause an enhanced effect of opioids?
alcohol
In which patients are opioids contraindicated?
- acute respiratory depression
- acute alcoholism
- raised intracranial pressure/head injury
In which patients should opioids be cautioned?
- hepatic impairment
- renal impairment
- elderly and debilitated
- convulsive disorders
What is a common side effect of Codeine?
constipation
What dosage would you prescribe when giving Dihydrocodeine?
30mg every 4-6 hours as necessary
What are the drug interactions of Dihydrocodeine?
- antidepressants
- dopaminergics (Parkinsonism)
Which patients should Dihydrocodeine be cautioned in?
- hypotension
- asthma
- pregnancy/lactation
- renal/hepatic disease
- elderly
If you suspect a patient is experiencing opioid overdose, what is the antidote?
NALOXONE
For which condition may a dentist prescribe carbamazepine?
Trigeminal neuralgia
What is the dosage of Carbamazepine to treat trigeminal neuralgia?
Starting dose: 100mg once or twice daily
—> increase gradually
Usual dose: 200mg 3-4 times daily, up to 1.6g daily in some patients
