Local anesthetics

Question 1

All local anesthetics work by blocking _______.

Answer 1

voltage-gated Na+ channels

Question 2

Are local anesthetics acids or bases?

Answer 2

weak bases

Question 3

Is a local anesthetic functional in its ionized (basic) or non-ionized form? Why?

Answer 3

non-ionized; to cross membranes

Question 4

Why won’t a local anesthetic work in an abscess?

Answer 4

acidic enviro

Question 5

What does the term “state-dependent blockade” refer to?

Answer 5

local anesthetics bind only to open Na+ channels, and therefore effect rapidly firing neurons first

Question 6

Which are are the first and last types of neuronal fibers inhibited by local anesthetics?

Answer 6

sympathetic and motor, respectively

Question 7

What are the 2 classes of local anesthetics?

Answer 7

amide and ester

Question 8

Which class of anesthetics do procaine, benzocaine, and tetracaine belong to?

Answer 8

ester

Question 9

Which class of local anesthetics do lidocaine and bupivicaine belong to?

Answer 9

amide

Question 10

Which class of local anesthetics is longer-acting?

Answer 10

amide (lidocaine and bupivicaine)

Question 11

Which class of local anesthetics is more likely to cause an allergic rxn?

Answer 11

ester (pro-, benzo-, and tetracaine)

Question 12

How/where are ester anesthetics metabolized?

Answer 12

plasma esterase

Question 13

How/where are amide anesthetics metabolized?

Answer 13

hepatic

Question 14

How many mg/mL of a local anesthetic are in a 1% solution?

Answer 14

10 mg/mL

Question 15

What is the pKa again?

Answer 15

The pH at which a base’s charged and uncharged forms are present in equal amounts.

Question 16

Generally, will a local anesthetic work faster if it has a higher or lower pKa?

Answer 16

lower

Question 17

Which 2 anesthetics are exceptional in that they have a high pKa but rapid onset of action?

Answer 17

procaine and chloroprocaine

Question 18

What physiochemical property of a local anesthetic is the primary determinant of its duration of action?

Answer 18

protein binding

Question 19

Why is epinephrine included in the “test dose” of anesthetic?

Answer 19

to ensure you are not in a blood vessel