LA pharmacologu u

Question 1

anlgesia

Answer 1

loss of pain alone

Question 2

anaesthesia

Answer 2

loss of all forms of sensation

Question 3

LA

Answer 3

loss of sensation in circumscribed areas of the body by a depression of exciation in nerve endings or inhibition of conduction process in peripheral nerves

Question 4

use of LA

Answer 4

1) controlling operative pain
2) controlling post operative pain
3) controlling operative haemorrhage
- due to vasocontrictors
4) diagnosis of pain
5) relief of orofacial pain- topical and injection

Question 5

contents of LA

Answer 5

• aesthetic agent (weak organic bases)
• vasoconstrictor(reduce blood flow)
• vehicle (ringers solution)
• reducing agent (sodium metabisulphite, prevents oxidation of adrenaline)
• fungicide (thymol)
• preservative (most preservative free today due to allergies

Question 6

anesthetic agent contents/composition

Answer 6

• Aromatic group linked.. (dissolved in lipid around nerves, important as we need it to go across the nerves)
• intermediate chain linked.. (links the two terminals)
• amino terminal (secondary or tertiary amine)

Question 7

the intermediate chains are either

Answer 7

esters

amides

Question 8

amide advantages

Answer 8

more stable
autoclaable
rarely antigenic

Question 9

most commonly used anaesthetic

Answer 9

lidocaine

Question 10

which molecuels are able to penetrate membrane of nerves and what does this mean

Answer 10

uncharged

- speed of onset is faster when there are more unchanrged molecules

Question 11

where are low pHs found

Answer 11

places of inflammation or infection

Question 12

what does the anesthetic drug penetrate

Answer 12

• epineurium
• perineurium
• endoneurium

Question 13

non spefici action of LA

Answer 13

lipophulic portion of the molecule may cause swelling of the membrane
blocks voltage gated sodium channels
initially increased thresold for excitation then condtion blocks

Question 14

vasoconstrictor effects

Answer 14

• block sympathetic vasoconstrictors (therefore dilation)

- direct effect on smooth muscle of vessels is variable (cocaine constricts, lidocaine dilates)

Question 15

detoxification for each type of LA

Answer 15

Esters broken down to
-	esterases in blood and liver
-	benzonic acids and alcohol
-	urine
Amides
-	mainly broken down in liver
-	oxidised
-	some conjugated with glucuronic acids
-	urine

Question 16

ideal characterisics of LA

Answer 16

1) produce complete local analgesia without damaging nerve or other local tissues
2) rapid onset with predictable and appropriate duration
3) isotonic with the tissues of the body
4) non toxic systemically
5) readily soluble and stable in solution (adequate shelf life eg 2-2 ½ years)
6) sterilizable (esters not autoclavable)
7) non addictive (not cocain)

Question 17

ad /disof having a vasocontricor i LA

Answer 17

• delay removal from site
• more rapid onset of anaesthesia
• prolongs and enhances effect
• reduces operative bleeding
  Disadvantages
• prolonged soft tissue anaesthesia unpopular with patients

Question 18

adrenaline typical usage

Answer 18

1:80,000 withlidocaine

Question 19

alternative to adrealine

Answer 19

felypressin (synthetic polypeptide)

less likely to produce cardiovasucalr efects than adrealine

Question 20

what does redycing agent do

Answer 20

• sodium metabisulphate to prevent oxidation of vasoconstrictors

Question 21

Mac recommended dose for lidocaine

Answer 21

lidocaine 4.4mg/kg
solution of 2% will contain 20mg/ml

65kg man
65x4.4 = 286mg max
286/20 = 14.3 ml of 2%
therefore 7.1 x2ml cartridges