Analgesia Flashcards
When is it best for a pt to start analgesics?
before LA wears off - get ahead of the pain
What drugs can we prescribe?
AAAAABBC
Aciclovir
Amoxicillin
Artificial saliva gel
Aspirin
azithromycin
beclometasone
benzydamine
carbamazepine
What is aciclovir?
Used to treat herpes simplex infection
can prescribe oral suspension or tablets
What is amoxicillin?
Antibiotic used for bacterial infections
What is azithromycin?
Antibiotic
good for pts allergic to penicillin
What is beclometasone used for?
Oral ulcers
What is carbamazepine used for?
relieves nerve pain - trigeminal neuralgia
What are the types of analgesics we can discuss with out pts?
Aspirin
Ibuprofen
Diclofenac
Paracetemol
Duhydrocodeine
Carbamazepine
What is pain?
unpleasant sensory and emotional experience associated with actual and potential tissue damage
What do trauma and infection lead to?
breakdown of membrane phospholipids which produce arachidonic acid which can then be broken down to prostoglandins
What can arachidonic acid be broken down to?
Prostoglandins
What are prostaglandins?
Group of lipids made at sites of tissue damage or infection that are involved ind ealing with injury and illness. - they control inflammation, blood flow, formation of clots and induction of labour
What do prostaglandins do?
Sensitise tissues to other inflammatory products such as leukotrienes which result in pain
What are leukotrienes?
lipid mediators that play role in acute and chronic inflammation and allergic diseases
What happens if prostaglandin production decreases?
This will moderate and pain will decrease
What is aspirin?
NSAD
What is NSAID effective at treating?
Dental and TMJ pain
What is diff between aspirin and paracetamol?
It has superior anti-inflammatory properties compared to paracetamol
What are the properties of aspirin? 5
Analgesic
anti-pyretic
anti-inflammatory
anti-plt
metabolic properties
Describe analgesic action of aspirin
Analgesic action is exerted both peripherally and centrally
What is the mechanism of action of aspirin?
Asprin REDUCES PRODUCTION OF PROSTAGLANDINS
It inhibits COX1 and COX2
COX 1 Inhibition results in inhibition of PLT aggregation for 7-10 days (life span of plt)
What does inhibition of COX1 do?
Inhibits PLT aggregation for life span of PLT (7-10 DAYS) whichh prevents production of pain causing prostaglandins and stops conversion of arachidonic acid to thromboxane A2 which induces PLT aggregation resulting in clots and harmful embolisms
What does COX1 inhibition stop conversion of?
Arachidonic acid –> thromboxane a2 which induces aggrigation of PLTs and can lead to clots
What is the issue with COX1 inhibition?
causes reduced plt aggregation which predisposes to damage of gastric mucosa
How can NSAIDs cause damage to gastroduodenal mucosa?
topical irritant effect on epithelium
impairment on barrier properties of mucosa
suppression of gastric PG synthesis
reduction of gastric mucosal blood flow
interfere with repair of superficial injury
What are some side effects/adverse reactions of aspirin?
GIT problems
hypersensitivity
overdose
aspirin burns
What GIT problems can aspirin cause?
can affect lining of stomach
this is because prostoglandins will inhibit gastric acid secretion and increase blood flow through the gastric mucosa and help producition of mucin by cells and aspirin reduces production of PGs
Why must care be taken in pts with GIT problems?
ulcers - aspirin interferes with stomaches ability to protect itself from damaging acids - promote ulcers by disrupting mucous that coats stomach lining
How does aspirin promote ulcers?
iNTERFERES with stomaches ability to protect itself from damaging acids - disrupts mucous that coats stomach lining
What do most pts taking aspirin suffer?
Some blood loss from the GIT but asymptomatic and not detectable
What are some allergic reactions to aspirin?
Minor rashes
itching
swelling
sob (care with asthmatics unless taken before)
asthma type attacks
What can overdose of aspirin cause?
Tinnitus
metabolic acidosis - can kill
coma
hyperventilation
What can aspirin do to mucosa?
Can cause mucosal burns
Why can aspirin cause mucosal burns?
effects of salicylic acid - aspirin shouldn’t be applied directly to mucosa as has NO TOPICLA EFFECT AND WILL CAUSE CHEMICAL BURNS IF APPLIED OT MUCOSA
What will pts sometimes do with aspirin if significant tooth pain?
may hold aspirin beside sore tooth however zero topical action and will result in chemical burn
Who shouldn’t be taking aspirin?
pts with:
- peptic ulcers
- epigastric pain
- bleeding disorders
- anticoagulants
- pregnancy and BF
- Steroid pts
- Renal and hepatic impairment pts
children under 16
asthma
allergy to other NSAIDs
taking there NSAIDs
elderly
G6PD deficiency
Why should pt with peptic ulcer not take aspirin?
can result in perf
Why should pt not take aspirin if epigastric pain?
may have undx ulcer
Why should pts not take aspirin if on other anticoaugs?
Double the effect of blood thinners
aspirin enhances warfarin
What interaction do aspirin and warfarin have?
aspirin displaces warfarin from binding sites on plasma proteins increasing free warfarin in blood so enhances its effect (majority of warfarin normally bound and inactive so if released then active increasing bleeding tendency)
Why should pregnant pts avoid aspirin?
Especially in 3rd trimester
can cause impairment of plt fuction which can increase risk of haemorrhage and jaundice in baby and prolong/delay labour
Why should pts on steroids avoid aspirin?
25% on long term steroids develop PUD so dont wanna risk perf
Where isa aspirin metabolised?
liver and excereted in kidney
Why is aspirin contraindicated in kidney impairment pts?
Excretion may be reduced or delayed resulting in drug being in body for longer - pt may need reduced dose or lease with team
Why is aspirin not used in chidlren 16 and under?
Can cause reyes syndrome
What is reyes syndrome?
Very rare disorder that can cause serious liver and brain damage if not tx quickly can lead to brain damage or death
When should aspirin be avoided in adoscelents?
if fever or viral infection
How does reyes syndrome work?
fatty degenerative process occurs in liver and kidney and profound swelling in brain (can die due to encephalopathy)
What is link between aspirin and asthma pts?
not contraindication but if not used before then best not to
What does taking a combo of NSAIDs increase?
Risk of side effects
Why are elderly more susceptible to drug induced side effects?
Smaller
smaller circulating BV
On other meds - poly pharmacy
have other med issues
What is aspirin complete contraindication in?
children and young people under 16
breastfeeding pts
previous or active pud
haemophilia
hypersensitivity to aspirin or any other nsaid
What dose of aspirin can pts take?
300mg 2 tablets 4x daily (every 4 hours) after food
What is max dose of aspirin?
4g
How many tablets can be taken of aspirin in one dose?
900mg - 3 tablets
What can’t be prescribed following extraction or minor surgery?
Aspirin
What is the thrombotic prophylaxis dose of aspirin?
75mg daily
after ischameic event - 150-300mg aspirin
If pt has active or previous PUD and paracetamol isn’t enough and aspirin can’t be prescribed what can pt take?
Pt can be prescribed NSAID and PPI such as lansoprazole or omeprazole
What does of lansoprazole should be taken if we prescribe PUD pt aspirin?
15mg capsules
5 capsules
1 daily
What dose of omeprazole should be taken if we prescribe PUD pt aspirin?
20mg capsules
5 capsules
1 day
What is ibuprofen?
NSAID OTC that has similar effect to aspirin however less effect on PLTs
How does ibuprofen work?
Ibuprofen (IBP) is one of the most commonly available over-the-counter pharmaceuticals in the world. The anti-inflammatory and analgesic properties of IBP are thought to arise from inhibition of COX-2 rather than COX-1
What are the properties of aspirin?
anti inflammatory
anti-pyretic
analgesic
Why is ibuprofen better than aspirin?
Less effect on PLTS
lower risk of gastric mucosa irritation
What can ibuprofen be used for?
MILD TO MOD ODONTOGENIC PAIN, POST OP OR INFLAM PAIN
What is 5 day regime for ibuprofen
?
5 days
400mg tablet 1x 4x a day after food
What is max dose of ibuprofen?
2.4g
groups we are cautious when prescribing ibuprofen
previous or active pud
elderly
preg
BF
Renal cardiac or hepatic impairment
asthma
allergy to nsaids
on other nsaids
systemic steroids long term use
What are some side effects of ibuprofen?
GIT discomfort
occasional bleeding and ulceration
headache
dizzy
depression
nervousness
insomnia
vertigo
tinnitus
What can ibuprofen interact with?
ACE inhibitors
antibiotics
anticoags
anti depresants
corticosteroids
beta blockers
ca channel blockers
What are signs of ibuprofen overdose?
Nausea
vomiting
tinnitus (more serious toxicity is v uncommon)
How to reverse ibuprofen overdose?
activated charcoal if more than 400mg/kg within the hour
What form do we use to write a prescription in Scotland?
GP14
What do NSAIDs inhibit?
• COX and so reduce production of prostaglandins which sensitise tissues to other inflammatory mediators that result in pain
What does ibuprofen and aspirin predominantly inhibit?
inhibit COX-1 (ASPIRIN 150X MORE EFFECTIVE AT INHIBITING COX1) – The amount of aspirin required to have sufficient anti-inflammatory effects by inhibition of COX2 will cause gastric damage due to amount of COX-1 inhibition
What does COX 1 do?
allows PLT aggregation (produces prostaglandins that activate PLTs)
COX-1 is the cyclo-oxygenase predominantly responsible for catalysing the reaction that produces prostaglandins associated with:
• Platelet aggregation
• Protection of the gastric mucosa
What does COX 2 do?
catalyses the conversion of arachidonic acid to prostaglandins.
COX-2 is the enzyme responsible for the generation of most of the inflammatory prostaglandins (although in some situations COX-1 is also involved)
What are actions of prostaglandins dependent on?
o The pathological situation
o Whether they are formed by COX1 or COX2
o Whether they are formed in excessive amounts
Summary of how NSAIDs work
NSAIDs inhibit cyclo-oxygenases and so reduce prostaglandins (which sensitise the tissues to other inflammatory mediators resulting in pain).
What do ibuprofen and aspirin predonomiantly inhibit?
COX 1
what is action of cox1?
allows pLT aggregation
What is cox2 action?
COX-2 is the enzyme responsible for the generation of most of the inflammatory prostaglandins (although in some situations COX-1 is also involved)
What is idea behind cox2 selective inhibitors?
cox2 predominantly responsible for analgesic action and is we dont target cox1 then less gastric irritation
What is Celebrex?
selective cox2 inhibitor
What is celebrex?
Useful anti-inflammatory actions and fewer GIT damaging actions compared with non-selective NSAIDs
as cox 2 is selectively inhibited sparing cox1 inhibition which can lead to gastric irritation
Why may selective cox2 inhibitors be too simplex of a view?
evidence that cox generated PGs can lead to gastric mucusal integrate and dcmic repair
however do have a lower risk of serious upper GIT side effects compared to non selective NSAIDs
What does BNF recommend for dental and orofacial pain?
COX 2 selective should only be chosen in pts at high risk of gastric or duodenal ulceration (history of peptic ulcer)
Who might tolerate highly selective cox2 inhibitors?
clotting disorder pts as dont have effect on plt aggregation
What is contraindicated in pts with active PUD?
ALL NSAIDS
What is paracetemol?
simple analgesic without anti-inflammatory activity
What are the properties of paracetamol?
analgesic
antipyretic
no anti-inflammatory action
no effects on bleeding time
doesn’t interact with warfarin
less irritating to git
suitable for kids
What does the metabolism of arachidonic acid by cox generate?
Hydroperoxides which exert a positive feedback to stimulate cox activity - this produces prostaglandins which sensitise tissues to other inflammatory mediators that result in pain
How does paracetamol work?
the metabolism of arachidonic acid by cox generates hydroperoxides which have a positive feedback effect producing cox adcitivty resulting in prostaglandins which sensitise other tissues to inflammatory mediators resulting in pain
paracetamol blocks this positive feedback mechanism and indirectly inhibits COX
What does paracetamol indirectly inhibit?
COX by blocking the positive feedback action of hydroperoxides resulting in analgesia and antipyretic action
Where is the main site of action for paracetamol?
Reduction of prostaglandins in the pain pathways of the CNS such as the thalamus
Why does paracetamol have little to no gastric mucosal effect?
not much effect on peripheral prostaglandins
paracetamol cautions when prescribing?
hepatic impairement
renal impairment
alcohol dependence
What are the rare side effects of paracetamol?
rashes
blood distorders
liver damage
What is the interactions of paracetamol with other drugs?
prolonged use can enhance effects potentially of anticoagulant effects of the coumarins such as warfarin
cytotoxics
lipid regulating drugs
What is the appropriate regime for mild to moderate Odontogenic pain with paracetamol?
5 day regime
500mg-1g up to 4 times a day
what is max dose of paracetamol?
4g
What can overdose of paracetamol cause?
hepatic damage that doesn’t become apparent till 4-6 days
How much paracetamol required for overdose?
10-15g in 24hrs
What should we warn pts when taking paracetamol?
Dont exceed maximum dose!! take as we have advised
dont take any other paracetamol containing drugs at same time such as lemsip or cocodamol
How many tablets needed for paracetamol OD?
10-15G
20-30 TABLETS
150MG/LG
what can paracetamol overdose lead to?
severe hepatocellular necrosis
less freq renal tubular necrosis
What dose can those aged 1-18 take?
500mg x 4 day
What are symptoms of overdose?
anorexia
nausea
vomiting
usually settles within 24hrs but if beyond then abdo paint nd can indicate development of hepatic necrosis
liver damage 3-4 days after ingestion and can lead to jaundice, haemorrhage, renal failure, encephalopathy, death
What is an opioid analgesic we can prescribe?
dihydrocodeine
What does opiod analgesia do?
it acts in the spinal cord (ind oral horn pathways associated with paelo-spinothalamic pathways)
causes central regulation of pain in periaqueductal grey matter, nucleus rectularis paragigantocellularis, raphe magnus nculeus
how do opioid analgesics product their effects?
via specific receptors closely associated with neuronal pathways that transmit pain to cns
What does BNF state about opioid analgesics?
Relatively ineffective in dental pain
Wha is the problem with opioid analgesia?
Dependence
tolerance
effects on SM
What is the issue with opioid analgesics and dependence?
Withdrawl of drug will lead to psychological cravings and pt will also be physically ill
What is tolerance with opioid analgesia?
this is where at achieve same therupatic affects the dose needs to be progressively increased
What effects can opioid analgesia have on the SM?
constipation
urinary and bile retention
What do opiod analgesics depress?
pain centre
reps centres
higher centres
cough centres
vasomotor
What can opioid analgesia often stimulate?
vomiting centre - limits its value id dental pain
What are some side effects of opioid analgesia?
dry mouth
sweating
headahce
tacky
palpatations
hypothermia
hallucianations
mood changes
reduced libido
What are some cautions with opioid analgesia?
dependance
elderly
hypotension
asthma
hypothyroidism
pregnancy
renal impairment
What is opioid analgesics contraindicated?
in acute alcoholism
acute respiratory depression
raised icp/head injury
What is codeine?
Codeine is an opiate and prodrug of Morphine used to treat pain, coughing, and diarrhea
1/12thy potency of morphine
taken orally
What is codeine usually in combo with?
NSAID or paracetamol
What is dihydrocodeine?
dihydrocodeine belongs to a group of medicines called opiates. It works in the central nervous system and the brain to block pain signals to the rest of the body.
How can dihydrocodeine be taken?
SC OR IM - controlled
ORALL - not controlled
What is dose of dihydrocodeine we can prescribe?
30mg every 4-6 hours
we can only prescribe oral
What are some general opioid side effects?
nausea
vomiting
constipation
drowsiness
What does dihydrocodeine have serious interactions with?
antidepressants (Maois)
dopaminergics
What are general opioid cautions?
Hypotension Hypothyroidism Asthma Pregnancy/BF Renal/Hepatic disease Elderly/children
When should opioid analgesics never be prescribed?
o NEVER PRESCRIBE IN RAISED INTERCRANIAL PRESSURE/SUSPECTED HEAD INJURY
Why are opioid analgesics little use for dental pain?
due to side effects of nausea and vomiting it is often little value for dental pain
What is naloxone?
Used when opioid OD iff coma or bradypnoea
What is another category of pain meds beside NSAIDs and opioids?
neuropathic and functional pain such as
TRIGEMINAL NEURALGIA
POST HERPETIC NEUALGIA
FUCNTIONAL - TMJ OR ATYPICAL PAIN
What is the drug we can prescribe for neuropathic or functional pain?
carbamazepine
What can we prescribe for trigemnial neuralgia?
carbamazepine
What other drugs can be used for trigemnial neuralgia that aren’t on dental list?
Gabapentin
Phenytoin
What are the clinical features of trigemental neuralgia?
severe pain spasms - electric shock pain
unilateral normally
trigger spot
periods of remission
recurrences of greater severity
What does of carbamazepine do we prescribe for trigeminal neurgalia
100 or 200mg tablets once or twice daily but we can gradually increase to 200mg 3-4 times a day up to 1.6g
Side effects of carbamazepine?
diziness
ataxia
drowsiness
leucopenia and other blood disorders
monitor ps blod
when is carbamazepine contraindicated?
o AV conduction abnormalities (unless paced) o History of bone marrow depression o Porphyria o Hepatic/renal/Cardiac disease o Skin reactions o History of haematological rxns to other drugs o Glaucoma o Pregnancy/BF o Avoid abrupt withdrawal
What are 5 drugs we must always be aware of?
aspirin iburpofen diclofenac
paracetamol
dihydrocodeine
carbamazepine
