Analgesia Flashcards
Analgesia in the dental practitioners formulary
- Aspirin (NSAID)
- ibuprofen (NSAID)
- diclofenac (NSAID)
- paracetamol
- dihydrocodeine (opioid)
- carbamazepine - can be used for trigeminal neuralgia
Properties of aspirin
- analgesic - reduce pain
- antipyretic - reduce temp
- anti - inflammatory
- metabolic
Mechanism of action for aspirin
- inhibits COX 1 and 2
- in turn reduces production of prostaglandins
Pain pathways
Tissue injury = injury to phospholipid cell membrane and release or arachidonic acid
Series of pathways releasing COX1 and COX2
= production of prostaglandins
Prostoglandins sensistise the tissue to other inflammatory products which result in pain
Analgesic properties of NSAIDS
-peripherally and centrally
-peripheral more
- inbition of prostaglandin synthesis
Antipyretic properties of NSAIDs
Reduced elevated temp in fever
Prevents rise in brain prostaglandin levels and interleukin 1 effects
Anti-inflammatory properties of NSAIDS
Prostaglandins vasodilate and affect capillary permeability
Aspirin reduces redness and swelling
Adverse side effects of aspirin
GIT problems - ulcers , inhibits gastric acid secretion , affects mucosal lining
Hypersensitivity - asthma, rash
Overdose - tinnitus , metabolic acidosis
Aspirin burns - if held in buccal sulcus
Groups to avoid prescribing aspirin
- peptic ulceration
-epigastric pain
-bleeding abnormalities
-anti-coagulants
-pregnancy - 3rd trimester
-on steroids
-breastfeeding - Reye’s syndrome - renal/hepatic impairment
-children under 16
-asthma
-elderly
What is nephrotoxicity
Can be caused by aspirin
Inhibition of renal prostaglandins synthesis may result in - renal failure, sodium retention
NSAIDS may cause interstitial nephritis and hyperkalaemia
Which groups is aspirin completely contra-indicated in
Under 16
Previous or active peptic ulceration
Haemophilia
Hypersensitivity to aspirin or other NSAID
Max dose of ibuprofen
2.4 g a day
Who to be cautious prescribing ibuprofen to
- previous or active peptic ulceration
- elderly
- pregnancy and lactation
- renal, cardiac or hepatic impairment
- history of hypersensitivity to NSAIDS
- asthma
- taking other NSAIDS
- patients on long term systemic steroids
Side effects of ibuprofen
- GIT discomfort
-hypersensitivity - headache, dizzy
What are some potential drug interactions with ibuprofen
- ACE inhibitors
- anticoagulants
- diuretics
-other NSAIDS
-antibiotics
Effects of paracetamol
- analgesic
- antipyretic
- little or no inflammatory action
- no effect on bleeding time
- does not interact with warfarin
- less irritant to GIT
- suitable for children
Mode of action of paracetamol
- hydroperoxides from arachidonic acid by COX and positive feedback to stimulate COX activity
- blocked by paracetamol , inhibits COX in brain
-analgesia and antipyretic action
Caution when prescribing paracetamol
- hepatic impairment
- renal impairment
- alcohol dependence
Which drugs can interact with paracetamol
Anticoagulant
Cytotoxic
Domperidone
Lipid regulating drugs
Metoclopramide
Dose of paracetamol
4g daily - 8 tablets
Paracetamol overdose
10-15g can cause hepato-cellular necrosis and renal tubular necrosis
Liver damage is maximal 3-4 days after Ingestion
Where do opioids act
Spinal cord
- dorsal horn pathways
-central regulation of pain
- they produce their effects via specific receptors which are closely associated with neuronal pathways that transmit pain to the CNS
- opioid analgesics are relatively ineffective in dental pain
Problems with opioids
- dependence
-tolerance
-effect on smooth muscle
-effects enhanced by alcohol
Contraindications for opioids
- acute respiratory depression
- acute alcoholism
- raised intracranial pressure/head injury
- interferes with respiration
- affects pupillary responses vital for neurological assessment
Which opioid can dentists prescribe
Dihydrocodine
Side effects of dihydrocodeine
Respiratory depression
Hypotension
Nausea
Drowsiness
Dose of dihydrocodeine
30mg 4-6 hours
Cautions for dihydrocodeine
- hypotensions
- asthma
- pregnancy
- renal or hepatic disease
- elderly or children
never prescribe in raised intracranial pressure or head injury
If coma from dihydrocodeine what is antidote
Naxolone
Which drug can be given for trigeminal neuralgia
Carbamazepine
100-200mg 3-4x daily
