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