Local Anaesthesia Pharmacology

Question 1

contents of LA?

Answer 1

LA agent
vasoconstrictor 
reducing agent
fungicide
preservative
carrier solution

Question 2

purpose of vasoconstrictor?

Answer 2

prolongs anaesthetic time

Question 3

purpose of reducing agent?

Answer 3

prevents oxidation of vasoconstrictor

competes with adrenaline for O2

Question 4

purpose of preservative?

Answer 4

without, shelf life = 18months to 2 years

can provoke an allergic reaction

Question 5

example of a fungicide?

Answer 5

thymol

Question 6

purpose of carrier solution?

Answer 6

modified ringers lactate solution , adjusted for biocompatible pH

Question 7

details of lidocaine?

Answer 7

2% solution 
dissolved in hydrochloride salt
in topical pastes
on its own - no lasting pulpal anaesthesia
\+ epinephrine 1:80 000

Question 8

prilocaine?

Answer 8

3% with octapressin
4% plain
prilocaine with octapressin sim to lidocaine with epinephrine
less effective at controlling haemorrhage, only slight vasoconstrictive properties

Question 9

mepivicaine?

Answer 9

2% 1:100000 epinephrine sim to lido/ep

3% plain sim to prilocaine plain

Question 10

articaine?

Answer 10

4% 1:100000/1:200000 epinephrine
sim to lido and ep
more quickly metabolised
useful for repeat injections

Question 11

epinephrine?

Answer 11

more profound anaesthesia
longer lasting
haemostasis

Question 12

felypressin?

Answer 12

sim to vasopressin
conc 0.03iu/ml
not as effective at haemorrhage as ep

Question 13

what kind of toxicity can occur?

Answer 13

intravascular
systemic distribution of relatively high doses of anaesthetic and vasoconstrictor
sufficient LA in a cartridge to give toxic levels of agent in CNS of children and small adults

Question 14

what LA for a pt with a latex allergy?

Answer 14

citanest

Question 15

pt’s with liver disease be wary of?

Answer 15

high risk of toxicity because of impaired metabolism

Question 16

what can impact on cardiac disease?

Answer 16

use of epinephrine

Question 17

if a pt has cardiac disease give what?

Answer 17

felypressin - max 3 cartridges

Question 18

problems with pregnant pt’s and la?

Answer 18

felypressin mimics oxytocin - effect on uterus

100 cartidges - induce labour

Question 19

max doses for av. 70kg pt?

Answer 19

lidocaine 2% plain - 11
lidocaine 2% 1:80 000 - 6.8

prilocaine - 3% octapressin 0.03iu/ml = 9
prilocaine 4% plain =4

Question 20

limit dose of analgesic with?

Answer 20

beta blocker = 2 cartridges with ep

calcium channel blockers

Question 21

limit dose of vasoconstrictor with?

Answer 21

beta blockers, diuretics, ca channel blockers, antiparkinson drugs

Question 22

cocaine/cannabis in past 24 hours avoid?

Answer 22

epinephrine

Question 23

medical contra indications to LA?

Answer 23

leukaemia, anticoagulant therapy
steroid therapy, liver dysfunction, renal disease, pregnancy,
rheumatic fever, uncontrolled diabetes, taxaemia, haemophilia

Question 24

local complications to LA?

Answer 24

infection, haematoma, nerve damage, facial palsy