Test 3: Local Anesthetics Specific Drugs to Know

Question 1

Which is the most widely used LA?

Answer 1

Lidocaine

Question 2

Why has spinal use of Lidocaine declined?

Answer 2

Due to TNS

Question 3

What does Lidocaine due to the vasculature depending on concentration?

Answer 3

-Vasodilates at most concentrations.
-Vasoconstricts at low doses.

Question 4

Epi + Lido can prolong the DOA by as much as?

Answer 4

50%

Question 5

Which LA is the least systemically toxic amide?

Answer 5

Prilocaine

Question 6

Why does Prilocaine cause Methemoglobinemia?

Answer 6

Due to its metabolites: O-toluidine (oxidizing agent)

Question 7

Can you use Mepivacaine in OB?

Answer 7

C/I in OB because its metabolism is prolonged in fetus and newborns.

Question 8

What are the uses of Lidocaine?

Answer 8

-Can be used for all blocks
-Can be given topically or nebulized.

Question 9

What type of molecule is Bupivacaine?

Answer 9

A racemic mixture

Question 10

What is Bupivacaine used in?

Answer 10

-Regional
-Local
-Spinal
-Epidural

Question 11

With Bupivacaine, ___ block outlasts ____ block.

Answer 11

Sensory block outlasts motor block.

Question 12

How long can Bupivacaine last in a PNB vs Intrathecal?

Answer 12

-PNB: 12-24 hours
-SAB: 2-3 hours with 4-6 hours of analgesia
-Used with Epi

Question 13

What is the biggest risk with Bupivacaine?

Answer 13

Can cause sudden cardiac arrest.

Question 14

What concentration of Bupivacaine is C/I in OB?

Answer 14

0.75%

Question 15

How does Ropivacaine compare to Bupivacaine?

Answer 15

-Structure is similar
-Ropi is a single enantiomer with less toxicity
-Can be administered in larger doses
-Less lipid soluble and less potent than Bupiv
-Vasoconstricts at low doses

Question 16

Epidural use of Ropivacaine allows for what?

Answer 16

Sensory > Motor blockage.

Question 17

Why does procaine cause allergic reactions?

Answer 17

Due to PABA metabolite

Question 18

Which agent is the least toxic of all agents currently in use?

Answer 18

Chloroprocaine
-Low potency & low toxicity
-Used in high concentrations
-Rapidly metabolized
-Used in combo with longer acting LAs

Question 19

When is Chloroprocaine most commonly used?

Answer 19

In C/S with bicarb for rapid onset of surgical block.
-Virtually no transmission to the fetus

Question 20

What is important to know regarding Chloroprocaine and subsequent doses of another agent?

Answer 20

Chloroprocaine can interfere with subsequent doses of epidural amides or opioids.

Question 21

What is unique about Tetracaine?

Answer 21

It is very toxic.
-Cauda Equina syndrome appears with repeated spinal dosing.

Question 22

Which agent is the only natural LA?

Answer 22

Cocaine

Question 23

What are the CV effects of Cocaine?

Answer 23

Inhibits the neuronal reuptake of catecholamines resulting in HTN, dysrhythmias, tachycardia, and potentially cardiac arrest.

Question 24

What is the pKa of Benzocaine?

Answer 24

2.5 - 3.1. Very unusual.
-Almost permanently non-ionized.
-High potential for toxicity.

Question 25

What are the pharmacokinetics of Benzocaine?

Answer 25

-A secondary amine
-Permanently non-ionized
-Slow onset
-Short DOA
It penetrates the lipid bilayer and can directly inhibit the Na v without entering the axoplasm first.

Question 26

What toxicity is associated with Benzocaine?

Answer 26

Methemoglobinemia.

Question 27

What blocks is Benzocaine used in?

Answer 27

Topical anesthesia only.

Question 28

What is the DOA of Chloroprocaine?

Answer 28

Short: 15 - 30 minutes

Question 29

What is the max dosing of Chloroprocaine?

Answer 29

-Without Epi: 11 mg/kg not to exceed 800 mg
-With Epi: 14 mg/kg not to exceed 1000 mg

Question 30

What is the DOA of Lidocaine?

Answer 30

Medium: 30 - 60 minutes
-With Epi: 120 - 360 minutes

Question 31

What is the max dosing of Lidocaine?

Answer 31

-Without Epi: 4.5 mg/kg not to exceed 300 mg
-With Epi: 7 mg/kg

Question 32

What is the DOA of Bupivacaine?

Answer 32

-Long: 120 - 240 minutes
-With Epi: 180 - 420 minutes

Question 33

What is the max dosing of Bupivacaine?

Answer 33

-Without Epi: 2 mg/kg not to exceed 175 mg
-With Epi: 2.5 mg/kg not to exceed 225 mg

Question 34

What is the DOA of Ropivacaine?

Answer 34

Long: 120 -360 minutes

Question 35

What is the max dosing of Ropivacaine?

Answer 35

-3 mg, not to exceed 200 mg (with or without epi)