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Flashcards in local anesthetics Deck (28)
1

local anesthetics chemical structure

lipophilic group (aromatic ring) + intermediate chain + ionizable group (tertiary amine)

2

chemical properties of local anesthetics

ester links = prone to hydrolysis - shorter duration of action

cationic form = most active at receptor site

uncharged = penetrates biological membranes

3

importance of ester links in local anesthetics

prone to hydrolysis

4

importance of cationic form of local anesthetics

most active

5

importance of uncharged form of local anesthetics

penetrates biological membranes

6

how to enhance/lengthen duration of local anesthetics

vasocontrictors are given = usually EPI

dec systemic absorption by dec blood flow

dec systemic toxic effects

7

EPI in spinal anesthesia

acts at alpha 2 = inhibit substance P

8

cocaine as vasoconstrictor in local anesthetic

constricts BV by potentiating action of NE = preventing its own absorption

9

what metabolizes ester linked anesthetics

tissue and plasma esterases: pseudocholinesterase

10

what metabolizes/degrades amide linked local anesthetics

liver microsomal cytochrome p450

11

MOA of local anesthetic

block VG sodium channels
bind to receptors near intracellular end of channel - block it

stop AP

12

liposolubility vs toxicity in local anesthetics

greater liposolubility = grater toxicity

13

pKa vs speed of onset

closer pKa to body pH, faster the onset

14

procaine

short acting

15

chloroprocaine

short acting

16

lidocaine

intermediate acting

17

mepivacaine

intermediate acting

18

prilocaine

intermediate acting

19

tetracaine

long acting

20

bupivacaine

long acting

21

etidocaine

long acting

22

ropivacaine

long acting

23

local anesthetic toxicity of CNS

restless, tremor = clonic convulsions

respiratory failure

premedication with benzo provides prophylaxis against seizures

24

local anesthetic toxicity of CV

depress pacemaker activity, contractility

arteriolar dilation - hypotension

**cocaine can cause vasoconstriction and hypertension and arrhtymias

(bupivacaine is more cardiotoxic than others)

25

toxicity in blood

prilocaine large doses == accumulate o-toluidine

o-toluidine = oxidizing agent capable of forming methemoglobin

26

toxicity allergic reactions

ester types metabolize to PABA (p-aminobenzoic acid derivatives)

**important for people allergic to PABA**

BUT amides dont metabolize to PABA = no allergic reaction

27

esters vs amides

esters = have 1 "i"
amides = have 2"i"'s

esters = be careful of PABA allergy

28

local anesthetic interactions

procaine -> PABA = inhibits action of sulfonamides

avoid in pt taking sulfonamides