Analgesia in Oral Surgery Flashcards
What drugs are included in the Dental Practitioners Formulary for analgesia?
NSAIDs:
Aspirin
Ibuprofen
Diclofenac
Simple Analgesics:
Paracetamol
Opioids:
Dihydrocodeine
Neuropathic Pain:
Carbamazepine
Explain the basic mechanism of pain production involving prostaglandins
- Trauma and infection cause breakdown of membrane phospholipids
- Produces arachidonic acid
- Arachidonic acid breaks down to form prostaglandins
- Prostaglandins sensitize tissues to inflammatory products such as leukotrienes
- Prostaglandins themselves do not cause pain directly
- Decreasing prostaglandin production moderates pain
What is Aspirin’s historical significance in dental pain management?
Previously one of the main NSAIDs used
Effective for dental and TMJ pain
Superior anti-inflammatory properties to paracetamol
Less commonly used now (Ibuprofen more prevalent)
Available over the counter
Describe the four key properties of Aspirin
Analgesic:
Inhibits prostaglandin synthesis in inflamed tissues
Antipyretic: (temperature)
Anti-inflammatory:
Metabolic effects
How does Aspirin interact with cyclo-oxygenases (COX)?
what is the side effect
- Inhibits both COX-1 and COX-2
- More effective at inhibiting COX-1
- COX-1 inhibition reduces platelet aggregation
- Side effect: Increases risk of gastric mucosal damage
What are the critical groups that should avoid or carefully use Aspirin?
Medical Conditions:
Peptic ulceration
Bleeding abnormalities
Renal/Hepatic impairment
Asthma
Medication Interactions:
Anticoagulants
Patients on steroids
Demographic Considerations:
Children & Adolescents under 16
Pregnant/Breastfeeding women
Elderly
G6PD-deficiency patients
Specific Risks:
Hypersensitivity to NSAIDs
Concurrent NSAID use
History of epigastric pain
What are the most critical adverse effects of Aspirin?
GI, Hypersensitivity, Overdoes, RARE
Gastrointestinal:
Mucosal lining damage
Potential blood loss
Ulceration risk
Hypersensitivity Reactions:
Acute bronchospasm
Skin rashes
Urticaria
Angioedema
Overdose Symptoms:
Hyperventilation
Tinnitus
Metabolic acidosis
Potential coma
Unique Risks:
Aspirin burns (chemical effect of salicylic acid on oral mucosa)
Reye’s Syndrome in children
Why should patients with peptic ulceration avoid Aspirin?
Risk of gastric or duodenal ulcer perforation
Aspirin can further irritate existing ulcers
Increases risk of gastrointestinal bleeding
Potential for serious medical complications
What does epigastric pain mean in the context of Aspirin prescription?
Refers to pain or discomfort in the upper central abdomen
May indicate pre-existing gastro-oesophageal issues
Even without diagnosed ulcer, caution is necessary
Suggests potential sensitivity to gastrointestinal irritation
Why is Aspirin dangerous for patients with bleeding disorders?
Patients with bleeding problems (e.g., Haemophilia) have compromised clotting
Aspirin further reduces platelet function
Increases risk of uncontrolled bleeding
Can exacerbate existing bleeding tendencies
How does Aspirin interact with anticoagulant medications?
Enhances effects of warfarin and coumarin anticoagulants
Displaces warfarin from plasma protein binding sites
Increases free (active) warfarin
Significantly increases bleeding risk
Requires careful medical supervision
What are the risks of Aspirin during pregnancy and breastfeeding?
Pregnancy Risks (Especially 3rd Trimester):
Increased hemorrhage risk
Potential jaundice in newborn
May prolong or delay labor
Breastfeeding Risks:
Risk of Reye’s Syndrome in infants
Completely contraindicated during breastfeeding
Why require caution when prescribing Aspirin to patients on steroids?
Approximately 25% of long-term steroid users develop peptic ulcers
Undiagnosed ulcers may perforate when Aspirin is introduced
Increased risk of gastrointestinal complications
Requires thorough medical assessment before prescription
What makes Aspirin problematic for patients with kidney or liver issues?
Renal Impairment:
Reduced ability to excrete the drug
Risk of:
Sodium retention
Reduced renal blood flow
Potential renal failure
Interstitial nephritis
Hyperkalaemia
Hepatic Impairment:
Liver metabolizes Aspirin
Reduced capacity to process the drug
Potential for drug accumulation
Increased risk of toxicity
Why is Aspirin dangerous for children and adolescents?
Reye’s Syndrome Risks:
Very serious condition with up to 50% mortality
Fatty degenerative process in liver
Profound brain swelling
Completely contraindicated under 16 years
Avoid during fever or viral infections
Particularly dangerous during breast-feeding
How does Aspirin affect asthma patients?
Not completely contraindicated
Some asthmatics may tolerate NSAIDs
Potential for:
Acute bronchospasm
Severe allergic reactions
Requires careful patient history
Recommended to ask about prior NSAID use and reactions
What does NSAID hypersensitivity mean for Aspirin prescription?
Contraindicated in patients with:
History of hypersensitivity to Aspirin
Allergic reactions to other NSAIDs
Potential reactions include:
Acute bronchospasm
Skin rashes
Urticaria
Angioedema
Why should multiple NSAIDs not be used simultaneously?
Combining NSAIDs increases side effect risks
Potential for:
Enhanced gastrointestinal irritation
Increased bleeding risk
Compounded adverse effects
Reduces therapeutic benefits
Increases potential for drug toxicity
Why require special caution with Aspirin in elderly patients?
More susceptible to drug-induced side effects
Often have:
Smaller body mass
Reduced circulating blood volume
Multiple concurrent medications
Additional underlying health conditions
Increased risk of complications
Requires careful dosage and monitoring
What makes Aspirin risky for G6PD-deficient individuals?
Susceptible to acute haemolytic anaemia
Risk varies with dosage
Generally acceptable up to 1g daily
Requires individual medical assessment
What distinguishes Ibuprofen in dental pain management?
More commonly used than Aspirin in dentistry
NSAID with lower platelet effect
Less gastric irritation compared to Aspirin
May cause bronchospasm
Popular for post-operative analgesia
Maximum adult dose: 2.4g
Recently associated with increased cardiac event risk
What are the key considerations when prescribing Ibuprofen?
Medical History:
Previous peptic ulceration
Elderly patients
Renal, cardiac, or hepatic impairment
Medication Interactions:
Hypersensitivity to Aspirin/NSAIDs
Concurrent NSAID use
Long-term steroid use
Patient Conditions:
Pregnancy and lactation
Asthma
Potential drug interactions with multiple medication classes
What are symptoms of ibruprofen overdose and what is indicated if more than 400mg/kg has been ingested within the preceding hour?
Symptoms:
- Nausea
- Vomiting
- Tinnitus (more serious toxicity very uncommon)
Activated charcoal followed by symptomatic measures are indicated if more than 400mg/kg has been ingested within the preceding hour.
How is Paracetamol different from traditional NSAIDs?
Not truly an NSAID despite traditional classification
Analgesic and antipyretic
Minimal anti-inflammatory action
No effect on bleeding time
Minimal warfarin interaction
Less GIT irritation
Suitable for children
Explain the complex mechanism of Paracetamol
Blocks hydroperoxide feedback stimulating COX activity
Primarily acts centrally in the brain
Minimal peripheral prostaglandin reduction (inflmmation)
Antipyretic action
Alternative proposed mechanisms:
Reduced 5HT production
NMDA receptor interference in spinal pathways
Exact mode of action remains unclear
Why is Paracetamol overdose extremely dangerous?
what is the dose
10-15g (20-30 tablets) within 24 hours causes severe damage
Leads to hepatocellular necrosis
Potential renal tubular necrosis
Liver damage peaks 3-4 days post-ingestion
Can result in liver failure and death
Immediate hospital transfer required
Additional risk from combination medications
What are side effects of paracetamol?
- Rashes
- Blood disorders
- Hypotension reported on infusion
- Liver damage (and less frequently kidney damage) following overdose
What drugs does paracetamol interact with?
- Anticoagulants (prolonged regular use of Paracetamol possibly enhances the anticoagulant effects of the coumarins)
- Cytotoxics
- Domperidone
- Lipid-regulating drugs
- Metoclopramide
What is the dose for paracetamol?
500mg tablets
- Adults: 1-2 tablets (0.5-1g) 4-6 hourly Max. Dose: 4g daily (8 tablets)
What are the key characteristics of Opioid Analgesics?
Act in spinal cord, especially dorsal horn pathways
Work via specific neuronal receptors
BNF states: Relatively ineffective in dental pain
Produce psychological and physical dependence
Develop tolerance over time
What are the major physiological impacts of Opioids?
CNS, Smooth Muscle
CNS Depression:
Pain center alteration
Higher center suppression
Respiratory center depression
Cough center suppression
Smooth Muscle Effects:
Constipation
Urinary retention
Bile retention
What are problems with opioid?
Opioid Problems: Dependence
Withdrawal of the drug will lead to psychological cravings and the patient will also be physically ill
Opioid Problems: Tolerance
To achieve the same therapeutic effects the dose of the drug needs to be progressively increased
What are side effects of opioids?
- The most common are; nausea, vomiting & drowsiness
- Larger doses produce respiratory depression & hypotension
What conditions are cautioned by opiod use?
- Hypotension
- Hypothyroidism
- Asthma
- Decreased respiratory reserve
- Pregnancy/Breast-feeding
- May precipitate coma in hepatic impairment (reduce dose or avoid)
- Renal impairment (reduce dose or avoid) - Elderly & debilitated (reduce dose)
- Convulsive disorders
- Dependence
What are the contraindications of opiods?
- Acute respiratory depression
- Acute alcoholism
- Raised intracranial pressure/head injury
- Interferes with respiration
- Affects pupillary responses vital for neurological assessment.
What are the qualities of codeine?
- A natural alkaloid found in opium poppy - 1/12th the potency of morphine
- Effective orally
- Low dependence
- Usually in combination with NSAIDs or Paracetamol e.g. Co- codamol (8mg Codeine : 500mg Paracetamol)
- Effective cough suppressant
- Common side effect – constipation - Available over the counter
What is the only codeine combinaion avaliable on the dental list?
dihydrocodeine (oral)
What are the routes of dihydrocodeine and what is the dosage?
*Routes: SC/IM/Oral
- Oral Dose: 30mg every 4-6 hours as necessary
What are the serious drug interactions of dihydrocodeine?
- Antidepressants MAOIs
- Dopaminergics (Parkinsonism)
What are the cautions for dihydrocodeine?
- See General Opioid Cautions - Hypotension
- Asthma
- Pregnancy/lactation
- Renal/Hepatic disease - Elderly/Children
Remember: Never prescribe in raised intracranial pressure/suspected head injury
What are the uses/disadvantages for dihydrocodeine?
- Uses: Moderate to severe pain
- However, BNF states that due to the side effects of nausea and vomiting it is of little value for dental pain
- Patients look ill – very pale
- BNF also states that it is not very effective for post-operative dental pain
What is opiod overdose and what is the antidote?
- Opioids cause varying degrees of coma, respiratory depression, and pinpoint pupils
- The specific antidote Naloxone is indicated if there is coma or bradypnoea
- Naloxone has a shorter duration of action than many opioids. Therefore, close monitoring and repeated injections/infusion may be necessary
What characterizes neuropathic and functional pain in dentistry?
what medicine can be used?
Conditions:
Trigeminal neuralgia
Post-herpetic neuralgia
Functional pain (e.g., TMJ, Atypical facial pain)
Dental Formulary Option:
Carbamazepine (Tegretol)
Anti-convulsant
Primary treatment for trigeminal neuralgia
Describe the specific characteristics of Trigeminal Neuralgia
Pain Characteristics:
Severe, brief spasms (like electric shock)
Seconds-long duration
Epidemiological Features:
Usually unilateral
More common in older age groups
More frequent in females
Disease Progression:
Identifiable trigger spots
Periods of remission
Recurrences often more severe
How is Carbamazepine used in managing neuropathic pain?
What potential treatments are avaliable not on dental list?
Dosage:
Start 100-200mg once or twice daily
Gradual increase based on response
Usual dose: 200mg 3-4 times daily
Maximum: Up to 1.6g daily
Specific for trigeminal neuralgia
Other potential treatments not on dental list:
Gabapentin
Phenytoin
