37: Local Anesthetic Agents Flashcards Preview

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Flashcards in 37: Local Anesthetic Agents Deck (35):
1

loss of sensation limited to a local area or region of the body

local anesthesia

2

drug that blcoks generation and propagation of nerve impulse that results in reversible, regional loss of function

local anesthetic

3

advantages and disadvantages of perineural infiltration v. nerve block

- perineural requires larger amounts of drug
+ perineural is easy to do
- nerve block requires more skill
+ less drug used in nerve block

4

injection of agent into CSF in lumbar subarachnoid space to reach the roots of spinal nerves that supply specific region

spinal block

more reliable than epidural, but time limited

5

injection of agent into extradural space and blockade of the nerve root as it passes through the space

epidural block

not time limited, can be used 4-7 days post op

6

primary MOA of local anesthetics

blockade of voltage-gated sodium channels

7

site of action of most clinically used drugs =

intracellular receptor and membrane expansion

8

"caine" =

local anesthetic

9

caine with two "i" in name =

amides

esters usually only have one i

10

t or f: all local anesthetics are acids

false

all local anesthetics are weak bases

11

most active form at sodium receptor =
form important for lipid penetration of membranes =

cationic form
uncharged base

12

smaller and more lipophilic local anesthetics are...

more potent
have faster rate of interaction with sodium channels
have longer duration of action

13

which of the two categories of local anesthetics is metabolized in the liver and has a longer-half life (longer duration of action)?

amides

esters are metabolized in the plasma and have a short duration of action

14

minimum anesthetic concentration Cm =

minimum concentration of drug for standard block

this is a relative standard of potency

15

increasing fiber size ---> _______ Cm

increasing

smallest fibers are most sensitive and myelinated nerves are more sensitive than non-myelinated

16

increasing pH ---> ________ Cm

decreasing

17

____ frequency nerves are more sensitive to anesthetics

higher

18

increasing Ca2+ concentration --> ______ Cm

increasing

19

why would you use a vasoconstrictor such as epinephrine with anesthetics?

vasoconstrictors reduce local blood flow and reduce systemic absorption and reduce toxicity, increased duration of action

**never inject LA with vasoconstrictor into areas with end arterioles (digits, toes, ear lobe, penis)

20

most important factor affecting the reversal of local anesthesia

absorption into circulation

21

drugs with _____ protein binding produce less toxicity

little

22

esters are metabolized in the plasma via ______ into ______

BChE

PABA * prone to allergic reactions

23

what is the treatment for LAST local anesthetic toxicity

intravenous lipid emulsion aka IntraLipid

forms a lipid sink to absorb circulation lipophilic toxin

24

which anesthetic can be given topically AND by injection?

lidocaine

25

most common epidural going to C-section when total motor block also desired

2% lidocaine

26

toxicity of lidocaine

potential for transient neurological symptoms TNS with spinal administration- pan and/or increased sensitivity to touch

27

clinical use for bupivacaine

- agent of choice for epidural infusion used for labor analgesia and postoperative pain
- excellent spinal anesthetic

28

clinical use for articaine

dental anesthetic

29

current use for cocaine

topical anesthetic for ENT procedures

30

topical only anesthesia due to enhanced lipid solubility

benzocaine

31

clinical use for chloroprocaine

used as epidural agent for labor anesthesia (especially cesarean section) due to lower risk of systemic toxicity or fetal exposure

32

encased bupivicaine that provides relief for up to 72 hr post op given as single dose injectio

exparel-liposome

33

lidocaine + prilocaine

EMLA eutectic mixture of local anesthetics

used as topical anesthetic on intact skin

34

tetracaine + adrenalin + cocaine =

TAC

topical used in pediatric emergency rooms

35

neurolytic agents are not reversible and achieve a permanent local anesthesia. what are their uses?

permanent block in terminal cancer or some other chronic condition

ethyl alcohol and phenol