Topicals - Quiz 5

What are the 2 types of topical anesthetic agents?

1) Professional Topicals
2) OTC Topicals

What are professional topical anesthetics used for?

• to LOWER pain on needle insertion
• treatment for minor injuries to soft tissue
• to increase comfort during minor dental procedures
• to decrease the gag reflex

What is the mechanism of action of topical anesthetics?

Blocks nerve conduction at mucous membrane

similar to injectable LAs, ↓Na+ permeability = ↓depolarization

What form of topical anesthetic is not recommended and why?

unmetered spray

- not recommend because you can't be sure of how much was delivered

What is the range of effectiveness for topical anesthetics?

0.2-20% depending on the form

What forms of LAs have association with methomoglobanemia?

1) 4% prilocaine (if MRD is exceeded)

2) benzocaine (14-20% conc. SPRAYS)

How should the anesthetic be applied pre-injection?

1) small amount of gel/ointment placed on a cotton tip applicator

2) topical placed at site for 1-2 minutes

anesthesia tissue depth = 2-3mm

What are the 3 common topical anesthetics used in dentistry?

1) Benzocaine

2) Lidocaine

3) Combination: benzocaine + butamben + tetracaine

What are the trade names for topical benzocaine?

hurricaine & lolli-caine

this is the one we use in clinic

What topical anesthetics are amides vs esters

ESTER:

- benzocaine

- combination

AMIDE:

- lidocaine

Where is each topical anesthetics metabolized?

LIVER:

- lidocaine

PLASMA + SOME LIVER:

- benzocaine

- combination (cetacaine)

What is the most common concentration of each topical anesthetic?

benzocaine: 20%

lidocaine: 2-5%

combination:

- 14% benzocaine

- 2% butamben

- 2% tetracaine

What is the onset and duration of benzocaine?

rapid onset: 30secs - 2mins

duration: 5-15mins

What is the onset and duration of lidocaine?

onset: 2-10mins

duration: 15-45mins

What is the MRD for lidocaine?

300mg, but only 200m safely

Which topical anesthetic would you recommend for a pregnant or breast feeding patient? and why

lidocaine

- category B & only a small amount enters breast milk

cetacaine can be used WITH CAUTION for breast feeding patients, NOT pregnant patients (category C)

What is the trade name for the combination topical?

cetacaine

What is the combination topical? (like what makes it up)

Benzocaine + Butamben + Tetracaine = Cetacaine

Cetacaine is an (ester/amide).

ESTER (all 3)

What is the onset and duration for cetacaine?

rapid onset: 30secs

duration: 30-60mins

What is the MRD for the combination topical anesthetic?

200mg

What is the concentration of the new topical agent: oraqix?

2.5% lidocaine + 2.5% prilocaine gel

only available by prescription

What factor increases topical toxicity?

↑blood levels

Why is an increased concentration needed for topical anesthetics vs injectables?

Topical anesthetics have ↑conc needed for diffusion through mucous membranes

They also don't have any vasoconstrictors so it tends to diffuse

What adverse reactions occur with topical anesthetic toxicity?

1) taste alteration

2) irritation at site of application

3) sloughing

4) CNS- excitation → depression

• CV effects = dec HR, dec BP, cardiac arrest

same signs/symptoms as injectable L.A.s