Analgesia Flashcards
what are the 6 main analgesics used in dentistry
aspirin
paracetamol
ibuprofen
diclofenac
dihydrocodeine
carbamazepine
briefly describe the pain pathway
tissue injury sees release of arachidonic acid which goes on to stimulate 2 pathways
1 - cyclooxygenase pathway concerning COX1 and COX2 , sees production of prostaglandins and thromboxane
2 - 5-lipooxygenase pathways , sees production of leukotrienes
function of prostaglandins
sensitise tissues to inflammatory products which cause pain and inflammation
what is the positive feedback mechanism assosciated with the cyclooxygenase pathway
hydroperoxides are generated from arachidonic acid metabolism and they have a positive feedback mechanism on stimulating COX production
i.e stimulating prostaglandin production
why might a mucosal burn occur if aspirin is placed topically
due to its salicylic acid content
should only be taken orally
how does aspirin work
works by inhibiting the cyclooxygenase pathway therefore decreasing prostaglandin production and therefore decreasing pain
how does ibuprofen work
works by inhibiting the cyclooxygenase pathway in the peripheries
decrease in prostaglandin production therefore also decrease in pain
why can NSAIDS such as ibuprofen cause GIT irritation
their mode of action sees decreased prostaglandin production
in the stomach prostaglandins
- inhibit gastric acid secretion
- increase blood flow in gastric mucosa
- aid mucin production by stomach cells
Groups to be cautious about prescribing ibuprofen to
- GIT issues , elderly, pregnant, lactating, renal impariment, hepatic impairment, asthmatics, hypersensitivity to any NSAID, taking other NSAIDs, taking long term systemic steroids
why should you be cautious prescribing ibuprofen to the elderly
- elderly - other medications and problems , more susceptible to side effects
why should you be cautious prescribing ibuprofen to pregnant women
- pregnancy - particularly 3rd trimester, can potentially cause a decrease in platelets so increased haemmhorage risk and increased risk of jaundice in the baby
why should you be cautious prescribing ibuprofen to women who are breastfeeding
risk of reyes syndrome - very rare
why should you be cautious prescribing ibuprofen to people with a renal or hepatic impairment
renal - ibuprofen excreted via kidneys
hepatic - ibuprofen metabolised in liver
side effects of ibuprofen
GIT discomfort, headache, ulceration , dizziness, hypersensitivity reactions e.g rash, bronchospasm, drowsiness
symptoms of ibuprofen overdose
nausea, vomiting, rarely - tinnitus (ringing within ears) sign of serious toxicity
treatment = activated charcoal
drug interactions with ibuprofen
many - check BNF
includes - antidepressants, antibiotics, anti coagulants, ACE inhibitors, corticosteroids, clopidogrel
what is ibuprofen and its properties
ibuprofen is an NSAID with anti - inflammatory, anti pyretic and analgesic properties
what is paracetamol and its properties
paracetamol is a simple analgesic and anti pyretic
NO anti inflammatory properties
also known as acetaminophen
paracetamol mode of action
blocks positive feedback mechanism of hydroperoxides on COX activity therefore decreasing prostaglandin actvivity
main target is in CNS e.g thalamus unlike NSAIDS which target peripheries
what 3 groups should you be cautious about prescribing paracetamol to
hepatic impairment - metabolised in liver
renal impairment - excreted in kidneys
alcohol dependent - excess alcohol in combination with paracetamol risks damaging liver
drug interactions of paracetamol
consult BNF
include lipid regulating drugs, cytotoxics, anti coagulants if prolonged paracetamol use
when would a paracetamol overdose become apparent
not till 3-4 days post overdose
cause is hepatic necrosis which takes this long to fully show
problems with opioid analgesics
dependence - psychological cravings and physically ill
tolerance - to achieve same therapeutic effect over time dose needs to be progressively increased
CNS effects - depresses pain , respiratory and cough centres
effect on smooth muscle - constipation , urinary and bile retention
what opioid analgesic is available in the dental practitioners formulary
dihydrocodeine
BNF states it is not thought to be effective at treating post op dental pain
contraindications for prescribing opioid analgesics
acute respiratory depression
acute alcoholism
raised intracranial pressure/ head injury
carbamazepine - what is it and why would it be used dentally
anticonvulsant medication used to treat neuropathic and functional pain such as trigeminal neuralgia
