Test One: LA And Fluoride

Question 0

What is the purpose of the benzene ring in the LA structure?

Answer 0

It is lipophilic which aids in crossing biological membranes

Question 1

What is the difference between an amide and an ester linkage for local anesthetics?

Answer 1

Metabolism and clinical efficacy; esters metabolized in tissue/plasma by plasma cholinesterase making it easier to cleave and inactivate, also higher chance of allergy

Amides metabolized in Liver

Question 2

Once inside the membranes how does the structure change?

Answer 2

Proton added to the tertiary amine at the other end to make it water soluble/polar

Question 3

What is the mechanism of action of LAs?

Answer 3

Blocks action potentials by blocking sodium channels in the BH+ form

Question 4

What is within a carpule of anesthesia?

Answer 4

Epinephrine, HCl or NaOH to adjust pH of solution, and metabisulfite (antioxidant to increase shelf life–cause of most allergies), isotonic NaCl

Question 5

Theories for mode of action on sodium channels

Answer 5

Membrane expansion theory: Incorporation into the membrane closes pores/passage of electrolytes
Receptor mechanism: physical occlusion, allosteric change in conformation
alteration of electrical field

Question 6

What phase of an action potential is affected by locals?

Answer 6

Phase 0-greatest influx of sodium ions; does not affect resting membrane potential

Question 7

What is a differential nerve blockade?

Answer 7

Loss of autonomic influence by blocking temp sensation, pain, touch, pressure, and motor function

Question 8

Why does cocaine not need epinephrine for vasoconstriction?

Answer 8

Cocaine prevents the reuptake of NTs which causes vasoconstriction

Question 9

How does infection/inflammation affect locals?

Answer 9

Lower pH in tissue, increased blood flow promoting clearance, alteration in Na channel function and number, increased response to noxious stimulants

Question 10

What processes do amides undergo during biotransformation?

Answer 10

Hepatic microsomal metabolism: Dealkylation and glucuronidation (any liver disease or decrease of hepatic circulation can cause systemic intolerance)

Question 11

Why does articaine have a low risk of toxicity?

Answer 11

Its ester side chain is metabolized in plasma very quickly

Question 12

How does renal clearance relate to protein binding capacity and pH of urine?

Answer 12

Inverse relationship with binding and inversely proportional to pH

Question 13

What effect do LAs have on the heart and why?

Answer 13

They can cause decreased contractility. Bupivicaine is a highly lipophilic anesthetic and wants to affect excitable tissue like the myocardium- can be cardiotoxic

Question 14

Most serious consequence of systemic LA toxicity?

Answer 14

postconvulsive central nervous system depression

Question 15

What are some adverse effects of intravascular injection of a LA?

Answer 15

Cardio and resp depression, neuro damage and death

Question 16

What is Clark’s rule for dosage?

Answer 16

Based on body weight. For a child: (weight in lbs. x adult dose)/ 150

Question 17

What is the max dose for xylocaine/lidocaine?

Answer 17

With epi: 7 mg/kg or 500 mg

Without epi: 4.5 mg/kg or 300 mg

Question 18

What is an adverse effect of prilocaine?

Answer 18

Methemoglobinemia: reduced capacity of hemoglobin to carry oxygen (also articaine and benzocaine)

Question 19

Why is bupivicaine not recommended for children or disabled people?

Answer 19

More potent and maybe toxic than lido; prolonged effect and greater potential for soft tissue injury

Question 20

What is a risk associated with 4% articaine and prilocaine?

Answer 20

Greater possibility of paresthesia

Question 21

What is the reversal agent for LA effects?

Answer 21

Phentolamine mesylate (OraVerse): Alpha adrenergic blocker

Question 22

What is epinephrine reversal?

Answer 22

Hypotension. This can be caused by antipsychotics like Prazosine which is an alpha1 blocker

Question 23

EMLA

Answer 23

Eugenic mixture of local anesthetics; topical cream for skin–2.5% lidocaine and prilocaine

Question 24

Oraqix

Answer 24

Intraoral preparation of EMLA- 50% pain reduction for srp

Question 25

Probable toxic dose for fluoride?

Answer 25

5 mg/kg-minimum dose that could cause life threatening systemic signs/symptoms

Question 26

Mechanism of action of fluoride

Answer 26

• inhibit enamel demineralization
• enhance enamel remineralization
• inhibit metabolism of carbs in cariogenic bacteria

Question 27

Tx for acute fluoride toxicity

Answer 27

• prevent further absorption with gastric levage using fluid high in Ca like milk
• cardiopulmonary monitoring
• blood analysis
• iv infusion of salts like calcium gluconate as a buffer
• alkaline diuresis to promote excretion

Question 28

Where and how does fluorosis (chronic toxicity) occur?

Answer 28

Excess ingestion of fluoride during development of teeth. Most commonly permanent canines and premolars and second molars. Once crowns are completely formed fluorosis is not possible.

Question 29

Fluoride poisoning signs

Answer 29

Nausea, vomiting, diarrhea, can progress to hypotension, hypocalcemia, and hypomagnesemia and acidosis–>severe cardiac dysfunction

Question 30

What concept is fluoridation of communal water supplies fulfilling?

Answer 30

Low concentration, high frequency

Question 31

Optimal fluoride concentration in cold, cool, and warm climate areas

Answer 31

Cold- 1.2 ppm
Cooler- 1.0 ppm (60% of pop has access to this concentration)
Warmer- 0.6-0.8 ppm

Question 32

What is the recommended fluoride concentration in schools and why is it different?

Answer 32

4.5 x higher than community because kids spend 1/4 of their time in school and they need to compensate for this lack of community exposure during these times

Question 33

What does dosage of prescribed fluoride supplements depend on?

Answer 33

Age and existing fluoride concentration in water supply

Question 34

What are the 3 fluoride formulations?

Answer 34

APF (acidulated phosphate fluoride), sodium fluoride, and stannous fluoride

Question 35

Which formulation of fluoride is preferred?

Answer 35

APF