Analgesia Flashcards by Megan Thompson

What systemic analgesics are most relevant to dentistry?

aspirin
ibuprofen
diclofenac
paracetamol
dihydrocodeine
carbamazepine

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How are prostaglandins formed?

trauma and infection lead to breakdown of membrane phospholipids producing arachidonic acid
arachidonic acid broken down to form prostaglandins

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What do prostaglandins do?

sensitise the tissues to other inflammatory products
results in pain

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What are leukotrienes?

inflammatory mediators
cause pain and inflammation

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What is aspirin used for?

effective for dental and TMJ pain
stroke prevention
can be bought over the counter

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What is the mechanism of action of aspirin?

inhibits cyclo-oxygenases (COX-1 & 2)
- more effective at inhibiting COX-1
  - reduces platelet aggregation
- reduces prostaglandin production

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What are the properties of aspirin?

anti-inflammatory (NSAID)
- superior to paracetamol
- reduced prostaglandins reduces vasodilation
analgesic
- peripherally and centrally
- peripheral actions predominate
- due to cycle-oxygenase inhibition
antipyretic
- prevents temperature raising effects of interleukin-1
- prevents rise in brain prostaglandin levels
- reduces elevated temperature, not normal temperature

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What are the adverse affects of aspirin?

gastro-intestinal problems
- mainly mucosal lining of stomach
- PGE2 and PGI1
  - inhibit gastric acid secretion
  - increase blood flow through gastric mucosa
  - cytoprotective action, production of mucin cells
- most patients will suffer some blood loss from GI tract
  - not macroscopically detectable
  - asymptomatic
hypersensitivity
- acute bronchospasm/asthma type attack
- skin rashes
- urticaria (hives)
- angioedema (facial swelling)
overdose
- tinitus/deafness
- vasodilation and sweating
- metabolic acidosis
- hyperventilation
- coma
- inability to regulate blood pH
aspirin burns
- mucosal
  - when applied locally
  - has no topical effect
  - must be stalled with water
- direct effect of salicylic acid

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Which groups should be avoided and where should caution be taken prescribing?

care taken in patients with gastrointestinal tract problems
- ulcers
- gastro-oesophageal reflux
- epigastric pain
- peptic ulceration (NEVER)
  - can result in perforation
care prescribing to asthmatics
- ask if any previous issues
bleeding abnormalities
- haemophilia (NEVER)
patients taking anticoagulants
- aspirin enhances warfarin and other coumarin anticoagulant activity
  - displaces warfarin from binding sites on plasma proteins
  - increase free warfarin, increases bleeding tendency
pregnancy/breast feeding (NEVER)
- especially in third trimester
- impaired platelet function risky near delivery
  - increased risk of haemorrhage
  - increased risk of jaundice
  - can prolong/delay labour
- Reye’s syndrome risk if breast feeding
patients taking steroids
- increased risk of peptic ulcer
- if undiagnosed can result in perforation
renal/hepatic impairment
- aspirin metabolised in the liver
- mainly excreted in the kidney
  - reduced/delayed excretion if impaired
- nephrotoxicity
  - inhibition of renal prostaglandin synthesis
  - sodium retention, reduced renal blood flow
  - renal toxicity
- interstitial nephritis and hyperkalaemia
under 16s
- risk of Reyes syndrome
  - 50% mortality (brain damage due to encephalopathy)
  - rare
  - fatty degenerative process in the liver
  - profound swelling in the brain
hypersensitivity to other NSAIDs (NEVER)
taking other NSAIDs
- combining will increase risk of side effects
elderly
- more susceptible to drug induced side effects
  - smaller circulating blood volume
  - other medical problems and taking medications
G6PD deficiency
- genetic condition
- enzyme deficiency in red blood cells
- glucose-6-phosphate dehydrogenase
- more susceptible to developing acute haemolytic anaemia

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What is the recommended dose of aspirin?

300mg tablets
- 2 tablets, 4 times a day
prescribed in conjunction in omeprazole

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What is ibuprofen used for?

post operative analgesia
- following oral surgery
available as paediatric suspension
more commonly used in dentistry than aspirin
- similar but not identical effect
- less effect on platelets and irritation to gastric mucosa
available over the counter

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What is the mechanism of action for ibuprofen?

inhibits cyclo-oxygenases (COX-1 & 2)
- reduces prostaglandin production

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What are the properties of ibuprofen?

anti-inflammatory
analgesic
antipyretic

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What are the potential adverse effects of ibuprofen?

gastrointestinal tract discomfort
- occasionally bleeding and ulceration
hypersensitivity reactions
- rashes
- angioedema
- brinchospams
other generic side effects
- headache
- dizziness
- nervousness
- depression
- drowsiness
- insomnia
- vertigo
- hearing disturbance/tinitus
- photosensitivity
- haematuria
- blood disorders
- fluid retention
- renal impairment
- hepatic damage
- pancreatitis
- eye changes
- Stevens-Johnson syndrome

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What groups should not be prescribed ibuprofen and where should care be taken?

previous or active peptic ulceration
elderly
pregnant and lactating
renal, cardiac or hepatic impairment
history of hypersensitivity to aspirin and other NSAIDs
asthma
taking other NSAIDs
long term systemic steroids

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What is the recommended dose of ibuprofen?

400mg tablets
- 1 tablet, 4 times a day (18+)
- reduced for under 18s
max adult dose is 2.4g

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What are the potential drug interactions with ibuprofen

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ACE inhibitors
other analgesics
antibiotics
anticoagulants
antidepressants
antidiabetics
corticosteroids
cytotoxics
diuretics
beta-blockers
calcium channel blockers
cardiac glycosides
ciclosporin
clonidine
clopidogrel
lithium
tacrolimus
vasodilator antihypertensives

What are the symptoms of ibuprofen overdose and how is it managed?

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symptoms
- nausea
- vomiting
- tinitus
management
- activated charcoal
- systemic measures if more than 400mg/kg ingested within an hour

What is the mechanism of action of paracetamol?

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inhibition of hydroperoxides
- generated from arachidonic acid
- stimulate COX activity
indirect inhibition of COX
- especially in brain
- main site of action is thalamus
does not affect peripheral prostaglandins
- little to no gastric mucosal irritation

What are the properties of paracetamol?

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analgesic
antipyretic

What are the potential adverse effects of paracetamol?

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rashes
blood disorders
hypotension
- reported on infusion
liver damage
- less frequently kidney damage
- following overdose

What groups should not be prescribed paracetamol and where should caution be taken?

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hepatic impairment
renal impairment
alcohol dependence

What are the potential drug interactions with paracetamol?

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anticoagulants (extended use enhances coumarin effect)
cytotoxics
domperidone
lipid regulating drugs
metoclopramide

What is the recommended dose of ibuprofen?

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400mg tablets
- 1 tablet, 4 times a day (18+)
- reduced for under 18s
max adult dose is 2.4g

What are the symptoms of paracetamol overdose and how is it managed?

- hepatocellular necrosis - maximal 3-4 days after ingestion - lack of early symptoms - liver failure resulting in death - renal tubular necrosis - less frequently

How do opioid analgesics work?

- act in the spinal cord - especially in dorsal horn pathways - central regulation of pain - specific receptors closely associated with neuronal pathways transmitting pain to CNS - relatively ineffective in dental pain

What problems do opioids pose?

- dependence - psychological and physical - withdrawal leads to psychological cravings and physical illness - tolerance - dose requires progressive increase - effect on smooth muscle - constipation - urinary and bile retention

What problems do opioids pose?

What are the side effects of opioids?

- nausea - vomiting - drowsiness - respiratory depression - hypotension - dry mouth - sweating - facial flushing - headache - vertigo - bradycardia - rashes - urticaria - pruritus - palpitations - hallucinations - dysphoria - mood changes - dependence - tachycardia

What groups should not be prescribed opioids and where should caution be taken?

- hypotension - hypothyroidism - asthma - decreased respiratory rate - pregnancy and breast feeding - hepatic impairment - can precipitate coma - renal impairment - elderly and debilitated - convulsive disorders - dependence - acute respiratory depression - acute alcoholism - raised intracranial pressure/head injury - interferes with respiration - affects pupillary responses vital for neurological assessment

What is codeine and how is it administered ?

- natural alkaloid found in opium poppy - 1/12th potency of morphine - low dependence - effective orally - usually combined with NSAIDs or paracetamol - available over the counter

What codeine can be prescribed by a dentist and what is it used for?

- dihydrocodeine - moderate to severe pain - not very effective for dental pain

What is the dose for dihydrocodeine and how is it administered?

- oral dose - 30mg every 4-6 hours as necessary - out with scope of dentistry - intramuscular and subcutaneousavailable - 40mg, 60mg and 120mg available

What are the side effects of dihydrocodeine?

- nausea - vomiting - constipation - drowsiness - respiratory depression - hypotension

What drugs interact with dihydrocodeine?

- antidepressants - monoamine oxidase inhibitors (MAOIs) - dopaminergic (Parkinsonism)

What groups should not be prescribed dihydrocodeine and where should caution be taken?

- hypotension - asthma - pregnancy and lactation - renal and hepatic disease - elderly - children - raised inter cranial pressure/suspected head injury

What are the symptoms of opioid overdose and how is it managed?

- coma - respiratory depression - pinpoint pupils - antidote is naloxone - use indicated by coma or bradypnoae - short duration of action (short half life) - close monitoring and repeat administration

What drug is used for neuropathic and functional pain?

- carbamazepine - trigeminal neuralgia - post-herpetic neuralgia - TMJ or atypical face pain

What type of drug is carbamazepine?

- anticonvulsant - tegretol

What are the clinical features of trigeminal neuralgia?

- severe spasms of electric shock like pain, lasting a few seconds - usually unilateral - older age group - trigger spots may be identified - more common in females than males - periods of remission - recurrences often of greater severity

What is the recommended dose of carbamazepine?

- usual dose is 200mg, 2-4 times daily - 100-200mg tablets - once or twice daily - gradually increase dose according to response - up to 1.6 g in some patients

Analgesia Flashcards

(41 cards)