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Flashcards in Anesthesia Part I Deck (198):
1

Difference btwn pharmakodynamics and pharmakokinetics:

Dynamics - how works

Kinetics - what body does to the drug

2

In LA, we are inhibiting Afferent or Efferent nn.

Afferent

(efferent goes out)

3

T/F
Onset, Duration, Potency, no allergic rxns, Stably, Sterile, readily undergoes biotransformation - are all desireable properties of LA's and no LA meets ALL criteria

True

4

LA's prevent both the ____ and the _____- of a nerve impulse

generation

conduction

5

What is the primary action of LA's in producing a conduction roadblock?

Decrease permeability of ion channels to sodium

*blocks sodium channels

6

Where do LA's work?

Na channels

7

LA's prevent Sodium channels from assuming what state?

Open (active)

8

The primary effects of LA's occur during what phase?

depolarization

9

LA's decrease the rate of ______ and prolong the rate of ________

depolarization

repolarization

10

T/F
Mostly LA works on C fibers, but we could go after myelinated fibers as well

True

11

What phospholipid bilayer membrane acts as a barrier to LA's

The outer layer of a neuron underlying its sheath:

Neurolemma

Axolemma

12

T/F
The myelin sheath insulates the axon both electrically and pharmacologically

True

13

T/F
The Nodes of Ranvier are the only site where molecules of LA have access to the nerve membrane - lots of Na channels

True

14

How many Nodes of Ranvier must be blocked to ensure effective anesthesia?

How many mm?

2-3 nodes

8-10 mm

15

What fiber carries information related to sharp pain?

What fiber carries information related to dull, aching pain?



A- delta

C fibers

*easier for LA to affect unmyelinated C fibers

16

What normally regulates the movement of Na ions across the nerve membrane?

Ca ions

*increase permeability of Na

17

LA molecules act by ______ antagonism with Calcium on the nerve membrane

Competitive

18

T/F
LA produce a depolarizing nerve blockade

False

*nondepolarizing

19

Mechanism of LA, displace _______

Bind ______

Ca++ ions

receptor site

20

LA molecules have a ______ aromatic ring

An intermediate linkage of either _____ or ______

And a terminal _______

lipophilic

Amide/Ester

amine

21

Only ____ containing LA's are available in the US and can be identified by a Nitrogen in the Intermediate Linkage

Amide

22

All LA's are weak _____

bases

23

What chemical property of LA's correlates with Potency?

Lipid Solubility of the Aromatic Ring

24

Bupivacaine is more/less potent than Lidocaine

It is prepared at ___% concentration

*Lidocaine prepared at ____% concentration

more

0.5%

*2%

25

In an LA molecule, what part is soluble in lipid?

Water?

aromatic

amino

26

What part of LA molecule is the "on-off switch" allowing LA to exist as either lipid or water soluble conformations?

Terminal amine

*tertiary/quaternary forms

27

Intermediate chain is either an Amide broken down in the _____

or and Ester broken down in the ______

Liver

Blood

28

What allows LA to be effective in tissues (chemical structure)?

Spacing between aromatic ring and secondary/tertiary amine

29

LA's are prepared as weak ______

Are combined with an acid to form a ______ (this makes stable/injectable solution)

bases

salt

30

All LA's are prepared as what?

Injected as what?

Weak bases

Acidic (HCl stored)

31

The salt form of LA exists as a ____ structure and will not penetrate the neuron

When exposed to physiologic pH (7.4), a proportion of molecules will convert to _______ structure that is lipid soluble

This determines what?

quaternary

tertiary

time of onset

32

What predicts the proportion of LA molecules in quaternary/tertiary structure when exposed to 7.4 physiologic pH?

pKa (ionization constant)

33

What speeds the onset of action and increases the clinical effectiveness of LA's?

Increasing pH

34

pH varies a lot in extracellular fluids but remains constant where?

interior nerve

35

Changes in extracellular pH profoundly alter what?

Ability of LA to block nerve impulses

36

Without a vasoconstrictor (epi) what is the pH of LA's?

With epi?

What does this explain?

5.5

3.3

burning sensation of LA's

37

LA's exist simultaneously as the base and the what?

Cation

RNH+ RN + H+

38

In order to get through the membrane, what form does the LA take?

In order to bind the receptor sites to block Na channels what form does the LA take?

Base molecule (RN) *lipophilic

Cation (RNH+) *hydrophilic

39

What form, Cation or Base, is the predominant in LA drug solutions?

RNH+ Cation

40

What is the sequence of Form when injecting and LA - as injected?

In response to 7.4 tissue pH?

Once exposed to axoplasm?

Cationic

Base (to pass through membrane)

Cation

41

Only ____ molecules can penetrate the nerve membrane

Only ____ molecules can bind receptor sites in channels

base

cation

42

Low pH shifts LA to what form?

If this exists in tissues what happens?

Cationic

decreases effectiveness b/c won't be able to penetrate membrane

43

The inclusion of more Cations in an injectable solution produces greater stability, increased solubility of powdered drug in water, and ease of sterilization

True

44

pH = pKa

50% Cation, 50% base

45

The higher the pKa, the more _____ form

This means what for the LA

Cationic

Longer onset

46

pKa ranges for LA's are usually what (very narrow)?

7.7 to 8.1

47

What drug is very potent but very slow diffusing?

*slowest diffusing, but used in prolonged operations

*highest pKa of any LA

Bupivacaine

48

The higher the pKa, the more _____ the ____ the onset, the more _____ it will be once inside the membrane

The lower the pKa, the more ____ , the ____ onset, the less _____ will be once inside the membrane

cations, greater time of onset, more effective

base, faster the onset, less effective

49

What additive to LA's that prolongs shelf life can trigger rxn if allergic to sulfites?

Sodium bisulfite

50

What has a slower onset, LA's with or without vasoconstrictors?

Without

*more base faster the onset - so acidic solutions take a longer time to buffer and cross membranes

51

LA's are effective on axons and free nerve endings and are can't penetrate skin

True

*except for EMLA, but slowly

52

Where can topicals diffuse to reach free nerve endings?

Mucous membranes

Injured skin

53

Why are topical nerve blocks ineffective in mucous membranes?

Low buffering capacity

54

Increasing the pH of a topical does what?

Increases potency

(less H+, less cation, more base)

55

T/F
Topicals are usually more concentrated than the injection version

True

56

Outside of nerve sheath:

Outside of nerve bundles:

Outside of nerves:

Epineurium

Perineurium

Endoneurium

57

In a nerve sheath, what is the greatest barrier to the penetration of LA?

Perineurium

58

What are the 1st bundles in a fascisulus reached by LA?

What are the last?

Mantle bundles

Core bundles

59

T/F
Mantle bundles innervate something close by

Core bundles innervate something far away

True

60

T/F
In no clinical situation are all fibers in a peripheral nerve blocked

True

61

Relate pKa and onset of action:

Lower pKa, greater onset of action

*more diffusable through membrane

62

What relates to potency?

What relates to duration of action?

Lipid solubility

Degree of protein binding (bupivacaine)

63

Duration of action and potency are opposites

True

Cationic is related to duration of action

Lipid solubility is related to potency

64

What affects both potency and duration of LA's?

Vasoactivity

vasodilators decrease

vasoconstrictors increase

65

T/F
All LA's are vasodilators, this is why we add vasoconstrictors (like epi)

True

66

T/F
Mantle bundles lose LA more readily than core bundles and recovery is a slower process than induction

True

67

Increasing tolerance to a drug that is administered repeatedly

Tachyphylaxis

68

Tachyphylaxis is more likely to develop in what case?

If nerve function allowed to return prior to second injection

69

3 factors that affect the rate of removal of an LA:

Degree of protein binding

vascularity of injection site

presence or absence of vasoconstrictor

70

The first-in-class anesthetic reversal agent is called ______ .

It significantly shortens recovery time and is a _____

Injection site used:

Oraverse

Vasodilator

same

71

When do LA's stop providing clinical effects?

When enter bloodstream

*can have other effects

72

The only LA that is a vasoconstrictor?

Cocaine

73

3 significant vasodilatory effects of LA:

Increase rate of absorption into blood

Decrease duration/quality of pain control

Increase blood conc. and potential for overdose (toxicity)

74

Once in the bloodstream, highly perfused organs receive more LA but the greatest percentage goes where?

Skeletal muscle

75

LA readily crosses BBB and placenta

True

76

Elimination of LA's follow what order kinetics

1st order kinetics

half lives (time necessary to remove 50%)

77

Esters are hydrolyzed in the blood by ______

byproduct is _____ excreted in the urine

Inherited disorder (1 in 2800) unable to hydrolyze esters in blood and contraindication for LA esters:

plasma cholinesterase

PABA

Atypical pseudocholinesterase

78

Amides are metabolized where?

What is a relative contraindication to use of these LA's?

Liver

ASA IV to V liver dysfunction

79

What LA undergoes primary metabolism in the liver with some in the lung, and can induce the formation of methemoglobin?

Prilocaine

80

What is the primary metabolite of Prilocaine (that leads to methemoglobin formation)

orthotoluidine

81

What metabolites of Lidocaine are responsible for producing sedation?

monoethylglycinexylidide

glycine xylidide

82

Systemic actions of LA's are related to the blood/plasma levels of the LA's

True

83

LA readily crosses the BBB and has what pharmacological action?

CNS depression

84

Overdose/Toxicity of LA's usually looks like what?

However, some LA's have ____ properties at lower/non toxic levels

Tonic-Clonic convulsions *inhibit inhibition

anticonvulsant

85

CVS effect of LA's

What LA is used as an anti-arrhythmic?

myocardial depression

Lidocaine

86

All LA's are vasodilators and create what in terms of BP?

hypotension

87

LA's have negative CVS effects at what blood levels?

Slight increase BP due to symp activity at what levels?

Mild hypotension at what levels?

Significantly elevated

non-overdose levels

approaching od levels

88

When does LA produce profound hypotension?

Overdose levels

89

What LA may produce fatal ventricular fibrillation at overdose?

Bupivacaine

90

What is more sensitive to irritating properties of LA than other tissues?

Most often associated with what?

Skeletal

Bupivacaine

91

At non-overdose levels LA's are a respiratory relaxant, and at overdose levels they can produce what?

resp arrest

92

Neuromuscular blockage is _____ when LA used w/ other relaxants

DDI's are ____ with other CNS depressants

Additive

Additive

93

Amides were once thought to contribute to what?

*there is no literature to support and is a genetic variant

Malignant hyperthermia

94

We only use Amide LA's in dentistry in the US, but where do we use esters?

topicals

95

Short duration of action for LA's:

Intermediate

Long

20-40 minutes

70 minutes

8 hours

96

T/F
A nerve block will provide longer duration of pulpal/soft tissue anesthesia compared to supraperiosteal infiltration

True

97

T/F
A larger than recommended dose increases duration

False

98

2 drugs with long duration:

2 drugs with short duration:

bupivacaine 0.5%, prilocaine 4% w/ epi

mepivacaine 4%, prilocaine 4%

99

T/F
1:50k or 1:100k will be better for hemostasis

True

100

A true, documented, reproducible allergy is what for an LA?

When to use alternative or lowest dose w/ least conc?

absolute contraindication

relative contraindication

101

T/F
You should have a minimum of 2 different drugs of varying duration of action in your practice

True

102

Short duration pulpal LA:

Intermediate pulpal LA:

Long pulpal LA:

30 min

60 min

90 min

103

The first synthetic LA was an Ester called...

It has the greatest _____ of LA's

It had a slow onset with means a high...

Novocain (procaine HCl)

vasodilation

pKa

104

What Ester combo LA was removed from the US market in 1996, was very toxic, and limited utility?

procaine HCl (novacaine) + propoxycaine

105

Norepinepherine isn't recommended why?

Necrosis

106

What is the Gold Standard LA - the drug against which all others are compared?

Lidocaine HCl

107

lidocaine is better than procaine (novacaine) in onset, potency, duration

worse in toxicity

True

108

T/F
Allergy to amide LA is common

False

*non-existent

109

What are the 2 pharmacologically active/potentially toxic metabolites to lidocaine HCl

monoethylglyceine

xylidide

110

Lidocaine onset of action

Effective dental concentration:

Safe for lactation?

pregnancy category:

Rapid, 2-3 minutes

2%

safe - doesn't enter milk

B

111

What are the 3 formulations of lidocaine (w/ colors)

lidocaine 2% w/ epi 1:50k (green)

lidocaine 2% w/ epi 1:100k (red)

lidocaine 2% plain (light blue) *vasodilatory, few applications

112

The duration and depth of anesthesia differs how between Red and Green?

lidocaine 2% 1:100k vs. lidocaine 2% 1:50k

Doesn't

113

Why is Red lidocaine 2% 1:100k preferred for dental procedures?

Safer

*for hyper responders, elderly, ASA, cardiac risk

114

What are the 1st signs/symptoms of LA overdose?

drowsiness, loss of consciousness, resp arrest

115

B/c Licodane is a depressant, what other use does it have for the CNS?

Anticonvulsant

116

What LA has similar actions to Lidocaine and lacks the duration of Bupivacaine?

mepivacaine HCl

117

What is the color/concentration of mepivacaine HCl

*similar to Lidocaine pharmacologically

mepivacaine HCl 3% w/o vasoconstrictor TAN

mepivacaine HCl 2% w/ levonordefrin 1:20k BROWN

118

What is the weakest vasodilator of all injectable LA?

mepivacaine

119

T/F
mepivacaine w/ levonordefrin 1:20k provides same hemostasis as epi

False

120

Like Lidocaine, Mepivacaine has near non-existant allergy and also possesses anticonvulsant properties

Also, follows more classic OD presentation of CNS stimulation followed by crash

True `

121

Relative potencies of LA's:

procaine

lidocaine, mepivacaine, prilocaine

articaine

bupivacaine

122

Mepivacaine Toxicity:

Metabolism:

Onset:

Safe during lactation?

similar to Articaine and Lidocaine

Liver: hydroxylation & N-demethylation

1-2 minutes (rapid)

unknown, use w/ caution

123

What drug is similar to Mepivacaine pharmacologically?

prilocaine HCl

124

prilocaine was thought to have decreased toxicity to lidocaine, but what was discovered?

reduces oxygen carrying capacity

***methemoglobinemia

125

Why is Prilocaine's end product CO2

Secondary Amine

126

What metabolite of Prilicaine induces formation of methemoglobin?

Orthotoluidine

127

T/F
Because Prilocaine reduces blood Oxygen carrying capacity, this limits the dose that can be safely given

True

128

T/F
despite its complications, Prilocaine is metabolized much more rapidly/completely than Lidocaine

True

129

What LA has biotransformation take place in the Lungs and Kidney as well as the Liver?

Prilocaine

130

What LA has faster Renal Clearance than all other Amides?

Prilocaine

131

What LA is considered to be less toxic systemically than comparable potent amides?

Prilocaine

*removed from circulation fast

132

The 2 formulations of Prilocaine:

4% Plain Black

4% w/ epi 1:200k Yellow

133

Why does Prilocaine 4% plain work well?

Weak vasodilator

*but NOT as weak as mepivacaine

134

What LA is good for epi sensitive pts?

Prilocaine

*least conc epi will produce lengthy anesthesia

135

Anything that produces ______ will be a relative contraindication to prilocaine

*this includes acetaminophen and phenacetin

methemoglobin (emia)

136

Prilocaine HCl potency:

toxicity:

metabolism:

excretion:

vasodilation:

onset:

concentration:

lactation safe?

equal to lidocaine, mepivacaine

half as toxic as lidocaine

liver, lungs, kidneys - rapid/complete

kidneys - fast renal clearance

less than lidocaine, more than mepivacaine

2-4 minutes

4%

use w/ caution - thought to enter breast milk

137

What LA is classified as an Amide but has a different ring structure?

This is a ______ ring - has a _____ atom on it that Increases solubility that has a ______ side chain

articaine

Thiophene - Sulfur, Ester

138

What LA is biotransformed in plasma and liver?

*rapidly in plasma

articaine

*ester off thiphene ring + amide

139

What has the fastest onset of the 5 injectable amide LA's?

articaine

140

Articaine has a high pKa, meaning fewer ____ molecules

Despite this, it's Sulfur/Ester ring makes it more _____

base

lipophilic

141

Articaine is available in what 2 formulations?

articaine 4% w/ epi 1:100k gold

articaine 4% w/ epi 1:200k silver

142

Because articaine has rapid metabolism and clearance, it presents ____ risk for systemic toxicity

less

143

What is the knock on articaine that probably isn't true?

paresthesia risk

144

T/F
Methemoglobiniemia may be a risk of articaine but no cases have been reported in dentistry

True

145

articaine HCl potency:

metabolism:

Excretion:

Vasodilation:

half life:

1/3 more potent than Lidocaine, mepivacaine, prilocaine

amide - liver ester - plasma cholinesterase

kidneys

equal to lidocaine, greater than mepivacaine/prilocaine

146

What LA has a lengthy duration and is usually only used in OS?

bupivacaine

147

Because bupivacaine lasts for so long, this decreases use of what?

post-op opioids

148

The slowest onset LA due to high pKa

bupivacaine

149

bupivacaine isn't recommende for what 2 demographics?

children

at risk for self injury (disabled)

150

What LA has the most profound vasodilating properties?

bupivacaine

151

Overdoses with ____ are uncommon, but more severe and not easily reduces b/c it is ______

bupivacaine

cardiotoxic

152

Adverse events with bupivacaine are rare b/c we use a lower dose than in medicine

True

153

bupivacaine formulation (and color)

bupivacaine 0.5% w/ epi 1:200k Blue

154

bupivacaine: Potency:

Toxicity:

Metabolism:

Extretion:

Vasodilation:

Onset:

half life:

most potent

most toxic

liver (slow by amidases)

kidney

most potent vasodilator

slowest (6-10 minutes)

longese - 2.7 hrs

155

Atrqumatic injections involve pre-injection numbing

True

156

Topical LA's don't contain what?

vasoconstrictors

157

T/F
blood levels by topical LA's can be as high as those injected

True

158

Many LA's aren't used topically why?

concentrations would be too high - risk for OD

159

almost all LA's aren't used topically with what notable exception?

Lidocaine

160

What ester is never injected, always Topical:

benzocaine

161

benzocaine may produce allergy w/ prolonged use why?

PABA metabolite

162

What topical is a ketone, equal in potency to cocaine, slow onset, unsuited for injection, and must be compounded at the pharmacy?

dyconine hydrochloride

163

2 forms of topical lidocaine:

lidocaine base 5% (poorly soluble)

lidocaine hydrochloride 10% (soluble)

164

What is the most potent dental topical LA with that also has a long duration or 45 minutes?

tetracaine hydrochloride

165

What combo topical LA contains 3 esters and has a duration of up to 45 minutes?

benzocaine, butamben, tetracaine

(Cetacaine)

166

What topical has higher concentrations of base forms of drugs, a long onset on skin, and a fast onset on mucosa?

Eutectic mixtures

167

2.5% lidocaine and 2.5% prilocaine Topical has what 2 formulations?

EMLA - medicine

Oraqix - dentistry

168

Where is Oraqix used?

It is a ____ mixture

Duration:

Intrapocket

Eutectic

20 min

169

Vasoconstrictors minimize the risk of LA toxicity, increase duration of action of LA, and provide hemostasis

True

170

2 Vasoconstrictors in Dental Anesthetics:

epinephrine (naturally occurring)

levonordefrin (synthetic)

171

catechol ring:

aromatic with a couple hydroxyls

*add a terminal amine = catecholamine

172

The dilution ratio:

grams drug dissolved: milliliters of solvent

grams: mL

173

Dilution ratio of epi used for anyphylaxis

1:1000

174

1:100,000 epi used is 1 gram: 100,000 mL solvent

True

175

epi concentration can be 1:1k, 1:50k, 1:100k, 1:200k

What is the concentration of levonordefrin?

1:20,000

176

What is the only product that used levonordefrin?

mepivacaine 2% (brown)

1:20,000

177

Match colors: Lidocaine 2% epi 1:100k:

lidocaine 2% epi 1:50k

lidocaine plain

mepivacaine 2% levonordefrin 1:20k

mepivacaine 3%

prilocaine 4% epi 1:200k

prilocaine 4%

bupivacaine 0.5% epi 1:200k

articaine 4% api 1:100k

articaine 4% epi 1:200k

red

green

blue

brown

tan

yellow

black

blue

gold

silver

178

most effective and widely used vasoconstrictor that affects heart and vasculature

peaks in plasma:

subsides:

epinephrine

5 minutes

20-30 min

179

What is an absolute contraindication to epi

Graves disease

180

Epinephrine is especially prone to deterioration via...

oxidation

181

Beta 1 = ______ effects

Cardiac

182

Beta 2 = ______ effects

coronary arteries, airway, skeletal

183

Epi always increases ____ BP

systolic

184

Epi decreases Diastolic pressure in what dose?

Increase in what dose?

small (beta 2)

large (alpha)

185

What type of epi effects predominate in hemostasis?

Alpha

186

In epi decline what type of effects predominate?

Beta-2

*vasodilation, post op bleeding

187

T/F
epi raises blood sugar levels

True

188

Endogenous epi is terminated by COMT and MAO in the liver

Exogenous epi is terminated by ______

COMT

189

A healthy pt can take how many mg of epi?

Cardiac dose?

0.2 mg (200 mcg)

.04 mg (40 mcg)

190

Limit Epi dose with what Cardio pts? (2)

ASA III and ASA IV

191

1:50k epi cartridge max for healthy pt (0.2 mg):

ASA III/IV pt (.04 mg):

5.5

1

*double these for 1:100k, double again for 1:200k

192

1:50k dilution is most effective at hemostasis, but what is the dilution of choice for at risk individuals?

1:100k

193

levonordefrin is a 75% _____ stimulator and a 25% ____ stimulator

direct alpha

beta

194

levonordefrin is ___% as potent as epi

15%

195

levonordefrin has more CNS/CVS effects compared to epi

False

*Less

196

levonordefrin, Hemostasis:

Resp:

CNS:

Metabolic:

Termination:

less than epi

less than epi

less potent than epi

less than epi

COMT (no MAO)

197

levonordefrin max dose health pts:

cardiac dose:

1 mg = (20 ml 1:20,000) = 11 cartridges

0.2 mg = 4 ml of 1:20,000 = 2 cartridges

198

Do not inject vasoconstrictors intravascularly, use safe injection technique ____

aspiration

Decks in Tim's Cards Class (140):