Oral Surgery - analgesia Flashcards
Describe the mechanism of pain.
trauma/infection breaks down phospholipids and produces arachidonic acid
A Acid is broken down to form prostaglandins
prostaglandins sensitises the tissues to other inflammatory products
the inflammatory products cause pain
List the properties of Aspirin
NSAID
Antiplatelet
analgesia
antipyretic
metabolic
Describe the mechanisms of action for aspirin.
reduces the production of prostaglandins by inhibiting COX 1 & 2
What is the action of COX 1 (inhibited in aspirin)
inhibits platelet aggregation and predisposes patients to gastric irritation
What is the action of COX 2 (inhibited in aspirin)
the enzyme responsible for the generation of inflammatory prostaglandins
Describe how aspirin provides antipyretic properties.
prevents temperature increasing the effects of interleukin 1
prevents an increase in brain prostaglandin levels
Describe how aspirin provides anti-inflammatory properties.
inhibits prostaglandins
P = redness and swelling as its is a vasodilator and affects capillary permeability
List the side effects of aspirin.
GIT irritation and bleeding
hypersensitivity
overdose
mucosal burns if applied locally
how would a patient with an aspirin overdose present?
hyperventilation
tinnitus
vasodilation and sweating
metabolic acidosis
coma
When should we avoid prescribing aspirin?
PEPTIC ULCERS - current or previous
GORD
BLEEDING ABNORMALITIES - HAEMOPHILIA
COAGULATED PATIENTS - aspirin enhances action of warfarin
STEROIDS - common to develop an ulcer anyway
PREGNANT AND BFEEDING - reyes syndrome, haemorrhage @ birth, baby jaundice, prolong/delay labour
CHILDREN < 16 = reyes syndrome
Avoid when severe - RENAL/HEPATIC IMPAIREMENT
(caution - ASTHMA)
HISTORY OF HYPERSENSITIVITY TO NSAIDS
ELDERY
G6PD DEFICIENCY
What is the recommended dosage of aspirin for pain?
300mg
2 tablets 4x per day
for 5 days
What is recommended if you have to give someone with a peptic ulcer aspirin for pain?
give alongside a PPI
lansoprazole or gastro-resistant omeprazole
1 per day for 5 days
What type of drug is ibuprofen?
NSAID
less side effects that aspirin
What is the recommended dosage of ibuprofen for pain?
1 tablet = 400mg
4 tablets a day
for 5 days
What is the maximum daily dose of ibuprofen?
2.4g
When prescribing ibuprofen, when should you exercise caution? (7)
PEPTIC ULCERS
ELDERLY
PREGNANT & BFEEDING
RENAL, HEPTIC CARDIAC IMPAIRMENT
HISTORY OF HYPERSENSITIVITY TO ASPIRIN AND OTHER NSAIDS
ASTHMA
LONG TERM SYSTEMIC STEROIDS
What are side effects of ibuprofen?
GIT discomfort, bleeding and ulceration
hypersensitivity reactions
headaches
dizziness
drowsiness
tinnitus
fluid retention
vertigo
renal & peptic damage
List ibuprofen drug interactions.
ACE inhibitors
BB
Ca channel backers
clopidogrel
antibiotics
anticoagulant
antidepressants
corticosteroids
How do you treat overdose of ibuprofen?
activated charcoal
What type of drug is a selective COX 2 inhibitor e.g. celecoxib?
NSAID
Describe the mechanism of selective COX 2 inhibitors.
inhibits COX 2 only and spares COX 1 as Inhibition of COX 2 is responsible for most of the analgesic properties of NSAIDS, cox 2 generates inflammatory prostaglandin
What are the advantages of using selective COX 2 inhibitors?
Since COX 1 isn’t inhibited then the patient is less likely to suffer with gastric irritation.
no effect of platelet aggregation
When would you avoid the use of selective COX 2 inhibitors?
this with current or a history of peptic ulceration
What type of drug is paracetamol?
analgesic
- no anti-inflammatory effect
Describe the mechanism of action of paracetamol.
Main mode of action: reduction of prostaglandins in the pain pathways of the CNS in the thalamus.
Paracetamol indirectly inhibits COX (especially in the brain) via the inhibition of the positive feedback
Arachidonic acid is metabolised by COX to produce Hydroperoxides and creates a positive feedback to stimulate COX activity again
with what patients should we exercise caution when prescribing paracetamol to?
hepatic and renal impairment
patient with alcohol dependance
drug interactions **
What are the drug interactions of paracetamol?
Anticoagulants
cytotoxic
domperidone
lipid regulating drugs
metoclopramide
What s the recommended dosage of paracetamol?
500mg
take 2 tablets 4x a day for 5 days
what is the maximum daily dose of paracetamol?
4g
What is the mechanism of opioids?
acts on the dorsal horn pathway of the spinal chord
what are the problems associated with opioid analgesia?
dependence - withdrawals lead to psychological and physical illness
tolerance
effect on smooth muscle cause constipation, urinary and bile retention
What do opioids suppress?
pain centre
respiratory centre
cough reflex
vasomotor
What do opioids stimulate?
vomiting
saliva
pupillary constriction
What are common side effects of opioids?
drowsiness
nauseam and vom
What are opioids enhanced by?
alcohol
with what patients should we avoid prescribing opioids to?
acute respiratory depression
alcoholism
raised intracranial pressure
with what patients should we exercise caution when prescribing opioids to?
hypotension
hypothyroidism
asthma & decreased respiratory reserve
pregnancy & BF
prostatic hyperplasia
hepatic& renal impairment
those with dependance issues
What s the recommended dosage of opioids?
30mg every 4-6 hours
What are the major drug interactions with opioids?
antidepressants
dopaminergics for parkinsons
How do you treat overdose of opioids?
Naloxone
What drugs are licences for use in trigeminal neuralgia?
carbamazepine
what is the dosages of carbamazepine?
start on 1 x 100mg tablet 1/2x per day
increase to;
1x 200mg tablet 3/4x per day
with what patients should we avoid prescribing carbamazepine to?
AV conduction abnormalities
bone marrow depression
porphyria
with what patients should we exercise caution when prescribing carbamazepine to?
hepatic, renal cardiac impairment
haematological reactions to drugs
glaucoma
pregnancy & BF
