Local Anesthetics

Front 1

Channels in _____ (negative potentials) have _____ for L.A. than channels in open (positive potential) or _____.

Back 1

resting state
lower affinity
inactivated states

Front 2

In _____, more channels are open or inactivated at any given time, therefore, the effect of L.A. is more pronounced

Back 2

rapidly firing axons

Front 3

What are the effects of time dependence with regards to local anesthetics?

Back 3

Sodium channels recover 100x slower than normal
Refractory period is increased
Nerves conduct fewer impulses

Front 4

With the application of increased local anesthetic what are the effects?

Back 4

1. Threshold increases
2. Impulse conduction slows
3. Rate of rise of AP declines
4. AP amplitude decreases
5. Ability to generate AP is gone

Front 5

What other factors can increase or decrease susceptibility to nerve blockade?

Back 5

1. Myelination (more sensitive)
2. Nerve fiber diameter
3. Firing Frequency
4. pH

Front 6

How many nodes must be exposed before conduction halts?

_____ fibers have shorter
critical length (fail to conduct)
than _____ diameter axons

Back 6

3

Small, large

Front 7

What are the sequential loss of sensations from LA?

Back 7

Pain > cold > warmth > touch > deep pressure > motor

Front 8

What form crosses the neuronal membrane?
What form blocks the sodium channels?
So what is going to increase blockage?

Back 8

Non-protonated form
Cationic form (BH+)
Solutions saturated with CO2

(Intracellular Acidosis)

Front 9

What does inflammation do to LA Onset?

So what's the solution?

Back 9

Inflammation lowers pH making Cationic form more abundant and can't cross neuronal membrane.

Add Bicarbonate and this raises pH and non-protonated form

Front 10

Proximity of site of injection to nervous tissues can influence _____, _____, _____ serum levels.

Back 10

onset, duration and peak

Front 11

_____ binding correlates with affinity of the L.A. for the receptor site in the sodium channel

What does this do to the duration of effect?

Back 11

Plasma protein

Increases

Front 12

Potential for _____ increase w/ increase plasma

Why?

Back 12

toxicity

because drug is not metabolized and sticks around longer

Front 13

_____ decrease as the pH decrease

What is this called?
_____ chance for toxicity by _____ free [active drug]

Back 13

% Bound drug
Acidotic state
Increase, increase

Front 14

What helps improve diffusion through the neuronal membrane?

Back 14

Lipids
(Less dosage required)

Front 15

Vasoconstrictors...
_____ duration of action (and local effect) by retarding removal from site of injection

_____ Rate of absorption into bloodstream

_____ chance of systemic toxicity by _____ levels in blood

Back 15

Increase
Decrease
Decrease, decrease

Front 16

What are the three common vasoconstrictors?

Back 16

Epi, levonordephrine, phenylephrine

Front 17

What vasoconstrictor decreases peripheral resistance, increases heart rate and stroke volume?

What kinds of complications can arise from this?

Back 17

Epi
Higher dose - increase BP, heart palpitations, chest pain

Front 18

What vasoconstrictor is a pure α-agonist?
What are its side effects?

Back 18

Phenylephrine
No increased HR, but may increase BP and decrease HR

Front 19

What vasoconstrictor has no β2 actions?
What are its side effects?

Back 19

Nordefrin and NE
Can increase BP and decrease HR

Front 20

What are the two classes of LA's?

Back 20

Esters and Amides

Front 21

How are esters inactivated?

How is it used?

Back 21

Hydrolysis by plasma esterases

Benzocaine - mainly topical, no longer packaged in carps

Front 22

How are amides metabolized?

Regular dosing may produce adverse reactions in patients with _____, as drug half-life is _____.

Back 22

Liver - some metabolites are active (Lido)

liver disease, increased

Front 23

What are adverse effects that are seen with low dosages of LA's?

Back 23

Sleepiness
Light-headedness
Visual & auditory disturbances Restlessness
Tongue numbness
Metallic taste

Front 24

What are the adverse effects that are seen with Medium dosages of LA's?

Back 24

Nystagmus
Muscle Twitching

Front 25

What are the adverse effects that are seen with the High dosages of LA's?

Back 25

Siezures and then CV collapse due to tonic-clonic convulsions

Front 26

How do you help prevent adverse effects from high dosage of used LA's?

Back 26

Pre-medicating with i.v. Diazepam

Front 27

Cardiovascular effects of LA's ...
Direct actions on _____

Indirect actions on _____

L.A. directly _____ pacemaker activity, excitability, conduction and strength of contraction

Cause arteriolar dilation which leads to ... _____

Back 27

Cardiac and smooth muscle
autonomic nerves
decrease
hypotension

Front 28

What is the most cardiotoxic LA?
What is the rarest form of toxicity?

Back 28

Bupivacaine
Local tissue toxicity

Front 29

Accumulation of metabolite of _____ from regional administration can cause methemoglobinemia; pt appears ...

Back 29

Prilocaine
cyanotic and blood appears brown (dose>400 mg)

Front 30

What LA's have hypersensitivity issues?

Back 30

Methylparaben
Metabisulfites

Front 31

What is the most commonly used LA?
What is it's duration of action?

Back 31

Lidocaine
1-3 Hrs. (increased with vasoconstrictor)

Front 32

What are the adverse side effects of Lidocaine?

Back 32

drowsiness
dizziness
heart block
arrhythmias
hypotension

Front 33

Topical anesthetics have a greater chance for toxicity when...

Back 33

The skin is abraided

Front 34

What are the most commonly used topical anesthetics in dentistry?

Back 34

Lidocaine
Prilocaine
Benzocaine

Front 35

What topical uses Lidocaine (2.5%) + prilocaine (2.5%)
Apply 5 min before procedures such as palatal injection and gingival sulcus probing

Back 35

EMLA Topical anesthetic cream

Front 36

What local anesthetic is applied to gingival sulcus for anesthesia for periodontal scaling and root planing?

Back 36

Oraqix

Front 37

What are the different types of Blocks?

Back 37

Infiltration Block
Field Block
Nerve Block