Local Anesthetics Flashcards by Alice Richards

3 components of the LA molecule

lipophilic

intermediate

hydrophilic

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aromatic portion of LA molecule

membrane penetration

lipophilic

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ester/amide portion of LA molecule

metabolic pathway

alter tonicity

intermediate

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amine portion of LA molecule

ionizable

determine charge

hydrophilic

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2 types of LA

ester A

amide B

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at normal body pH, LA are largely in the __ form

charged cationic

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metabolic pathway of ester A

plasma

AND

liver

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metabolic pathway of amide B

liver → CYP450

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LA are classified as weak __

bases

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uncharged LA are __ and cross membranes

lipophilic

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injected LA are __ and block Na channels

hydrophilic

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effect of infxn/inflammation on LA

infxn/inflammation → decreases pH → increased cationic/charged LA form → decreased membrane passage → decreased pain relief → increased dose required

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t/f: buffered LA are more effective

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2 esters A

tetracaine

benzocaine

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3 amides B

lidocaine

mepivacaine

bupivacaine

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bc esters are metabolized by plasma and liver, they have __ duration than amides

and higher risk for __

shorter

allergic rxn

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what 2 conditions increase t½ of amides 3x

liver dz

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3 factors that affect differential nerve block effectiveness

fiber size

firing rate of fibers

location of fibers

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most important factor in effectiveness of differential nerve block

fiber size

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which type of fiber is affected first in differential nerve block

small

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2 smallest pain fibers

sensory pain

PG sympathetic

affected 1st in nerve block

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what increases the effect of nerve bocks

neuron firing rate

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what type of pain fiber has the fastest firing rate

active sensory pain fibers

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what do you think when you see, dose dependent blockade

increased effectiveness of nerve block with faster firing rate of active sensory pain fibers

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in terms of location, which type of pain fiber is affected first

periphery

2 types of pain transmission fibers

A delta C

describe A delta fibers (2)

myelinated big

describe C pain fibers (2)

unmyelinated small

3 factors that decrease absorption of LA

oral topical intact skin

3 factors that increase absorption of LA

**broken skin** **injxn** → SC/IM/IV - *not infiltration* **vasoconstrictors**

which has higher distribution, amides or esters

amides → cross bbb/placenta

distribution of amides is __ in healthy people, which causes initial __ blood levels

increased lower

esters are metabolized __ than amides, resulting in __ potential for toxicity

faster lower

\_\_ have higher potential for liver toxicity

amides

blood concentration of LA depends on (4)

injxn rate/route/site dose liver dz vasoconstrictors

s.e of esters

allergic rxn

common s.e of lidocaine

**dizzy** **drowsy**

s.e of lidocaine at higher doses

convulsions CNS dpn death

tx for convulsions caused by lidocaine

diazepam midazopam

route of amide administration w. highest risk of methemoglobinemia

topical

2 LA w. highest risk for methemoglobinemia

lidocaine benzocaine

tx for methemoglobinemia

IV methylene blue

surface use of LA

mucous membranes

large dose of LA under skin w. epi

infiltration

regional use of LA

nerve block

spinal use of LA

subarachnoid

2 types of epidural

lumbar caudal

lumbar LA is used for

obstetrics

caudal LA is administered \_\_ and used for \_\_

above the coccyx perineal/rectal procedures

esters to know

cocaine chloroprocaine tetracaine benzocaine

least toxic ester

chloroprocaine

ester w. fastest onset

chloroprocaine

ester w. slowest onset

tetracaine

ester w. highest topical value

tetracaine

administration routes of tetracaine (3)

spray solution ointment

which ester is used topically at the dentist

benzocaine

s.e of benzocaine

methemeoglobinemia

which LA can be used topically on intact skin (2)

LMX-4 EMLA

which has faster onset, LMX-4 or EMLA

LMX-4

LMX-4 contains

lidocaine

EMLA contains

lidocaine/procaine

amides to know

lidocaine mepivicaine bupivicaine

lidocaine is same-same

xylocaine

which amide is mc administered via infiltration

lidocaine

meipivicaine is same-same

carbocaine

which amide has the slowest onset

bupivicaine

which amide has the longest duration

bupivicaine

list the amides in order of lowest to highest vasodilatory action

mepivicaine lidocaine bupivicaine

list the amides in order of safety in pregnancy from least to highest

mepivicaine bupivicaine lidocaine

which amide is cardiotoxic

bupivicaine

3 effects of vasodilation

increased blood to injection site decreased effects locally increased toxic systemic effects

4 effects of vasoconstrictors

decreased blood flow to injection site decreased hemorrhage risk decreased toxic effects of LA

epi dose for ASA I

1:100,000 200 mg

epi dose for ASA II-III

1:100,000 40 mcg (cardiac comorbidities)

Local Anesthetics Flashcards

(74 cards)