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House Pharmacology > LOCAL ANAESTHETICS > Flashcards

LOCAL ANAESTHETICS Flashcards

1
Q

Local anaesthetics prevent or relieve pain by _______________

They bind to a specific receptor site within the pore of the _____ channels in nerves and ___________ through this pore

A

interrupting nerve conduction

Na

block ion movement

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2
Q

Cocaine was discovered by _______ in ______ century

Indian natives chewed _______ extract of C.________ for its stimulatory and euphoric effects

Cocaine 1st Isolated by ______ in ____

He tasted it and noted that it caused a _________________

______________ studied cocaine physiological actions

A

serendipity

19th century; alkali

C.erythroxylum

Niemann in 1860

numbing of the tongue

Sigmund Freud

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3
Q

Cocaine is an ______ of ______ acid and the complex alcohol ______________________________

A

ester; benzoic

2-carbomethoxy,3- hydroxyl-tropane

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4
Q

Procaine was synthesized in ______

Hydrophilic moiety could be ______ or _______

Hydrophobic moiety must be _______

A

1905

tertiary or secondary amine

Aromatic

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5
Q

Cocaine

Ester (hydrolysed by __________ )or ______ linked (liver amidases)

Hydrophobicity increases both the ______ and the _________

Association of the drug at _______ sites enhances the __________ of the drug

A

plasma esterases; amide

potency; duration of action

hydrophobic; partitioning

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6
Q

SAR

Hydrophobicity also enhances _____ hence decreased ______

Molecular sizes influences ___________ from receptor site

Important In ________ tissues in which local anaesthetic bind during AP and dissociate During the period of ________________________.

_______ binding of local anaesthetic during action potential allows the _______ and ________ dependence of their action

A

toxicity ;Therapeutic index

rate of dissociation ; rapidly firing

membrane repolarization.

Rapid ; frequency

voltage

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7
Q

MOA

Local Anesthetic prevent the _________ and the _________ of the nerve impulse

Local Anesthetic block conduction by decreasing the (small or large?) (transient or prolonged?) increase In the permeability of excitable membranes to ______ that normally produceds ______________ of the membrane, Due to direct interaction with _______ gated _____ channels.

As the Local Anesthetic action progressively develops in a nerve, the threshold for ___________ gradually ______eases

A

generation ; conduction

large transient ; Na

light depolarization

voltage ; Na

electrical excitability ; increases

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8
Q

Frequency and voltage dependence of local anaesthetic

The degree of block depends on _________________________ and on its __________________

Resting nerve is much (more or less?) sensitive than repetitively stimulated

Higher frequency of stimulation the (more or less?) positive membrane potential cause a greater degree of anaesthetic block

A

nerve has been stimulated

resting membrane potentials

less ; more

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9
Q

Frequency and voltage dependence of local anaesthetic

local anaesthetic molecule in its ______ form gains access to its ______ site within the _____ only when the Na channel is in _______ state

They bind (Loosely or Tightly?) to and stabilizes the _________ state of the Na channel

local anaesthetic is slightly soluble as ____________________

Marketed as __________________ (HCl) thus increases their _______

It is the _______ species that interact with Na channels

A

charged ; binding

pore ; open state

tightly ; inactivated

unprotonated amines

water soluble salts (HCl); stability

cationic

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10
Q

Local Anesthetic Structures: Esters vs. Amides

Main issue:__________

Esters
Ester hydrolysis by _________

Amides
N-_______and ______ in the _____

If This patient has pre-existing ____ disease- we would worry about _______________

A

metabolic pathway

Hydrolysis; plasma cholinesterase

dealkylation; hydroxylation; liver

liver; accumulation of the drug

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11
Q

Entiomers

Substances of ______ shape
– Molecules existing in _______forms
Left and right handed

When dissolved in solution , they ______ polarized light
– _______ isomers

A

opposite

mirror image

rotate

– Optical

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12
Q

Important concept in local anesthetic toxicity

–______ handed molecules such as _______ are more toxic

A

Right

bupivacaine

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13
Q

Types of local anesthetic

_________
______ block
_________ block
IV
______ (CSF)
_________

A

Infilteration

Field

Nerve

Spinal

Epidural

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14
Q

Both ionized and non-ionized forms of Local Anesthetics are needed for function

T/F

A

T

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15
Q

In infected tissue, the local anesthetic is completely (ionized or non-ionized?) and won’t work- hence the need for _______ or _______

A

ionized

sedation

General anesthesia

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16
Q

Systemic Toxicity

CNS toxicity: due to ______ serum local
anesthetic blood levels

–___________________________________ is the most common etiologic factor in severe systemic reactions

•Toxicity can be gradual
– Same variables:
•Site, vascularity, total dose, use of a vasoconstrictor…

A

peak

Accidental intravascular injection

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17
Q

Systemic Toxicity

Symptoms: _________ symptoms to ______ or ______

Excitatory symptoms: Selective ————- of __________ neurons

Depression of CNS
______ channel block ______

A

Mild neurological

coma or death

depression of inhibitory

Na; centrally

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18
Q

Lipid soluble agents are (more or less?) potent and more toxic

A

More

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19
Q

Treatment of Toxicity

Get _______

Airway
–_______,_________, intubation or airway equipment

Drugs to stop seizure
____________,_________
•Other drugs/interventions

______________ management

A

assistance

Oxygen, ventilation

– Benzodiazepines, Barbiturates

Post seizure

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20
Q

Site of Injection: Likelihood of Toxicity

Most = ______> ________>_______

Least=________ < ___________

A

IV, Tracheal, Intercoastal

Subcutaneous , Sciatic/Femoral

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21
Q

LA

Duration =______ Binding = ____ Solubility

– Protein binding.
• increased protein binding = ______eased duration

– Lipid solubility
• increased lipid solubility= ______eased duration

A

Protein; Lipid

Increased

Increased

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22
Q

Adjuncts also _______ Duration

Eg Vaso_______

A

Prolong

constrictors

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23
Q

Adjuncts of LA

Vasoconstrictors
– _________/________/ ________

•________ duration
•( Minimize or Maximize?) effect of LA vaso ________
•_____eased toxicity
•_____ease intensity of block
•_____eased bleeding

A

Epinephrine/Phenylephrine/ Levonordefrin

Prolong; Minimize

dilatation

Decr; incr; Decr

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24
Q

Most drugs must enter the circulation to attain therapeutic blood levels before they can exert their clinical action

local anesthetics, on the other hand, _______________________________________

A

cease to provide any clinical effect once they leave the site of administration and enter into the blood stream

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25
Q

Uptake of Local Anesthetics

all local anesthetics possess some degree of vasoactivity; most producing some level of vaso____

ester local anesthetics are potent vaso_______ drugs

A

dilation; dilating

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26
Q

Uptake of Local Anesthetics

Procaine (_______) possesses tremendous vaso________ abilities which are employed to halt _________
(________________)

A

Novocaine

dilating; arteriospasm

accidental IA injection

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27
Q

Uptake of Local Anesthetics

_______is the only local anesthetic that consistently produces vasoconstriction

A

Cocaine

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28
Q

Cocaine

initial vaso_________  intense vaso____________

A

dilation

constriction

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29
Q

vasodilation leads to ______eased rate of
absorption of the local anesthetic into the blood, thus decreasing the _________ and ________ of _________ while increasing the ______________________ and potential for ______ (_____ reaction)

A

increased; duration

depth of pain control

anesthetic blood concentration

overdose (toxic reaction)

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30
Q

Distribution of Local Anesthetics
once in the blood, local anesthetics are distributed to ____ tissues

brain, head, liver, lungs, kidneys and spleen have high levels of local anesthetics due to their _____________

skeletal muscle has the highest level because it has the ______________

A

all; high level of perfusion

largest mass of tissue in the body

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31
Q

_____________ has the highest level of distributed local anesthetic

A

skeletal muscle

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32
Q

The blood level of local anesthetics is influenced by:

1) Rate at which the drug is _______ into the cardiovascular system

2) Rate of ________ from the vascular compartment to the tissues

3)________ of the drug through metabolic or excretory pathways

A

absorbed

distribution

Elimination

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33
Q

Only some local anesthetics cross the blood brain barrier

T/F

A

F

All local anesthetics cross the blood brain barrier

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34
Q

All local anesthetics cross the placenta and enter the blood stream of the developing fetus

T/F

A

T

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35
Q

PABA Metabolism (_________ Acid)

Ester Local Anesthetics: plasma ________

•hydrolyzed in the plasma by the enzyme ____________

•the rate of hydrolysis is related to the degree of _________

A

ParaAminoBenzoic

pseudocholinesterase,

pseudocholinesterase

toxicity

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36
Q

Tetracaine is hydrolyzed the (slowest or fastest?) which makes it ____ times (more or less?) toxic than _____ which is hydrolyzed the (slowest or fastest?)

A

Slowest

16; more

Chloroprocaine

Fastest

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37
Q

Slower Hydrolyzation = ____eased Toxicity

A

Increased

38
Q

Metabolism of Local Anesthetics

2) Amide Local Anesthetics:
primary site of metabolism of amide local anesthetics is the _____

Prilocaine is metabolized in the ____________

A

liver

liver and lung

39
Q

virtually the entire metabolic process occurs in the ________ for Lidocaine, Mepivicaine, Articaine, Bupivacaine and Etidocaine

A

liver

40
Q

______ function and hepatic ______ greatly affect the rate of metabolism (biotransformation) of amide local anesthetics

A

liver

perfusion

41
Q

significant ______________ (ASA IV/ASA V patients) represents a relative contraindication to the use of amide local anesthetics

A

liver dysfunction

42
Q

Articaine has a (shorter or longer?) half-life than other amides because a portion of its metabolism occurs in the ________________

A

Shorter

blood by plasma cholinesterase

43
Q

metabolism byproducts of _____ local anesthetics can possess clinical activity if allowed to ______ in the blood

A

amide

accumulate

44
Q

All local anesthetics have the ability to cause sedation

T/F

A

T

45
Q

large doses of Prilocaine can produce a side effect called __________

___________ , a primary metabolite of Prilocaine, induces the formation of methemoglobin

A

Methemoglobinemia

orthotoluidine

46
Q

large amounts of Lidocaine produce a ________ effect which is due primarily to two metabolites _________ and _______________

A

sedation

glycine xylidide and monoethylglycinexylidide

47
Q

If the local anesthetic has two “i”s in its name; it’s an (ester or amide?)

A

Amide

48
Q

Excretion of Local Anesthetics

_________ are the major excretory organs for both local
anesthetics

esters appear in very (small or large?) concentrations in the urine; this is because they are almost completely __________

A

kidneys; small; hydrolyzed in plasma

49
Q

Excretion of Local Anesthetics

Procaine (Novocaine) appears in the urine as 90% _____ and 2% _________

10% of Cocaine is found _______ in the urine

A

PABA; unchanged

unchanged

50
Q

Excretion of Local Anesthetics

patients undergoing ——— are likely to be unable to excrete the _______ portion of the esters or amides thus increasing toxicity

A

dialysis

unchanged

51
Q

Systemic Actions of Local Anesthetics

the pharmacological action of local anesthetics on the CNS is ________

At high levels, local anesthetics will produce ______-______ ————-

A

depression

tonic- clonic convulsions

52
Q

Systemic Actions of Local Anesthetics

Procaine, Lidocaine, Mepivacaine, Prilocaine and Cocaine generally produce anti-________ properties; this occurs at a blood level considerably (below or above?) that at which the same drugs cause seizures

A

convulsant

Below

53
Q

Procaine, Lidocaine and Mepivacaine have been used therapeutically to terminate or decrease the duration of ___________________________________ seizures; anti-convulsant levels
(.___to ___ micrograms/ml)

A

both grand mal and petit mal

5 to 4

54
Q

The depressant action of local anesthetics raise the ________ by decreasing the ______ of cortical neurons in epileptic patients

A

seizure threshold

excitability

55
Q

Preconvulsive Signs and Symptoms

_______ of the tongue and circumoral regions

anesthetic has been transported to these areas by the _________ rather than the _________ of the anesthetic

if ______ or ______ occurs in the first 5 to 10 minutes after local anesthetic delivery, it should serve as a warning that convulsive activity could be possible

A

numbness

cardiovascular system ; local delivery

excitation or sedation

56
Q

U.S. Air Force an U.S. Navy pilots are grounded for ______ following administration of ______ due to its mild effects of ______ and/or drowsiness

A

24 hours

Lidocaine

sedation

57
Q

Convulsive Phase

duration of seizures is related to _______ of anesthetic and inversely related to ___________ evels

at a normal pCO2, a Lidocaine blood level between 7.5 and 10 micrograms/ml usually result in a convulsive episode
when CO2 levels are increased, the blood level of local anesthetic necessary for seizures _____eases while the duration of the seizure _____eases

seizures usually last _____________________

cerebral blood flow and cerebral metabolism _____ease during a seizure

_____eased blood flow to the brain leads to an increase in the __________________________________________ to the brain causing a (shorter or longer?) seizure

A

blood level ; arterial pCO2 levels

decreases ;increases

less than or equal to one minute

increase; increased

volume of local anesthetic being delivered

longer

58
Q

Convulsive Phase

-____eased cerebral metabolism leads to (acidosis or alkalosis?) which (shortens or prolongs ?) the seizure activity even in the presence of declining local anesthetic levels in the blood

-seizures gradually subside , leading to generalized CNS _______ , respiratory _________ , respiratory ________, death

A

incr; acidosis; prolongs

depression; depression

arrest

59
Q

local anesthetics have a direct action of the myocardium and peripheral vasculature

T/F

A

T

60
Q

(CVS or CNS?) is more resistant to the effects local anesthetics than the (CVS or CNS?)

A

CVS

CNS

61
Q

Cardiovascular Effects of Local Anesthetics

increased local anesthetic blood levels result in _______ eased myocardial depolarization, with ,________ in resting membrane potential and ____________ of the stages of repolarization

A

decr

no change

no prolongation

62
Q

local anesthetics ____ease myocardial excitation, ____ease conduction rate and _____ease the force of contraction

A

decr; decr; decr

63
Q

Heart

Lidocaine is used therapeutically for _____________ contractions (PVCs) and ventricular ________

Local anesthetics cause ____tension from the direct _______ action on vascular smooth muscle

A

pre-ventricular

tachycardia

hypo

relaxant

64
Q

Lung Toxicity

local anesthetics have a direct ______ action on bronchial smooth muscle

generally, respiratory function is _______ by local anesthetics until ______ levels are achieved

A

relaxant

unaffected

near overdose

65
Q

Local Tissue Toxicity

skeletal muscle will heal within _______ of being injected with local anesthetic

longer acting local anesthetics ( _________ ) produce (more or less?) damage to skeletal muscle than do shorter acting agents

A

two weeks

Bupivacaine

More

66
Q

Malignant Hyperthermia:

pharmacogenic disorder in which a _________ alters the person’s _______________. Tachycardia, tachypnea (rapid breathing), unstable blood pressure, cyanosis, fever muscle rigidity and death; 68% mortality rate.

A

genetic variant

response to certain drugs

67
Q

Malignant Hyperthermia Association of the U.S. determined that there are no documented cases in Dental or Medical literature supporting the concept of _______ local anesthetics triggering malignant hyperthermia

A

amide

68
Q

Local and regional anesthesia involves the reversible ______ of a ________ to prevent ______________ without rendering ________

A

numbing

specific region of the body

any sensation of pain

the patient unconscious

69
Q

Local anesthesia involves reversibly blocking __________ and _______ near the site of administration (limited area)

Regional anesthesia involves reversibly blocking nerve areas and pain conduction of a __________

Both forms makes use of special drugs called _____________________

A

nerve endings and pain conduction

large part of the body

LOCAL ANESTHETICS

70
Q

TYPES

Local Anesthesia
–______
–__________
Regional Anesthesia
– _________
– _________
– _________
– _________ block
– _________ block

A

Topical; Infiltration

– Epidural
– Spinal
– Caudal
– Sympathetic block – Limb block

71
Q

CHEMISTRY

Local anesthetic agents are composed of –_________________ portion
–____________
–_________________ portion

A

Lipophilic aromatic

Intermediate chain

Hydrophilic amine

72
Q

CHEMISTRY

The intermediate chain has either an _______ linkage or an _______ linkage

A

ESTER

AMIDE

73
Q

CLASSIFICATION of LA

ESTERS

LIST 5

AMIDE

LIST 6

A

Cocaine
Benzocaine
Chloroprocaine
Procaine
Tetracaine

Lidocaine .
Bupivacaine.
Ropivacaine.
Etidocaine.
Mepivacaine.
Prilocaine.

74
Q

Cocaine
– Used ________
– Has a (slow or rapid?) onset of action; ___
– Duration of up to ———
– Causes VASO________ unlike others
– Lower concentrations are used for the ______
– Higher ones are used on the _______ and ________ mucosa.

A

topically

Rapid; 1 minute

2 hours; CONSTRICTION

eye; nasal and pharyngeal

75
Q

Cocaine
– It can be occasionally combined with _______ cocaine
– This can be ______ because the _______ potentiates the ______ toxicity

– It can also _______ the CNS leading to ———— and __________ (e.g., restlessness, excitement)

– Overdosage leads to ———- followed by CNS __________

A

Epinephrine

hazardous; catecholamine; cardiovascular

stimulate; euphoria and cortical stimulation

convulsions; depression.

76
Q

Benzocaine
– Benzocaine is a _____ derivative
– Used ______ on the ———- and ———
– Has a (low or high?) rate of absorption
– (Low or High?) incidence of systemic toxicity.
– Contraindicated in patients with known sensitivity to ____-linked anaesthetics or _____-containing compounds.

A

PABA

topically; skin and mucous surface

Low ; low

ester; PABA

77
Q

Chloroprocaine
– Formed from the combination of ______ and ————

– Has a (lesser or greater?) potency and (more or less?) toxicity than ordinary procaine

– (Slowly or Rapidly?) hydrolysed cholinesterase ((short or. Long?) T1/2)

– Commonly used in __________.

A

CHLORINE and PROCAINE

Greater ; less

Rapidly; short

obstetrics

78
Q

Procaine
– (Slowly or Rapidly?) ______ by _______
– Not effective _______
– Employed for _______, ____ block, and ______ anaesthesia.
– Relatively (slow or rapid?) onset
– Has a (short or long?) duration of action; _______
– Can be combined with ________.
– Available in _________ with __________ as the vasoconstrictor.

A

Rapidly hydrolysed by plasma cholinesterase

topically

infiltration, nerve block, and spinal anaesthesia.

slow; short ; 1 hr

epinephrine ; dental cartridges

phenylephrine

79
Q

Tetracaine
– It is an _________ of _________
– Usually given _________
– Can also be used for _________ anaesthesia.
– Can be combined with _________

– It has approximately a ____-minute onset
– About _________ duration of action.

A

ester ; PABA

topically; spinal

Epinephrine; 5-minute

2 to 3 hours

80
Q

Tetracaine is considerably (more or less?) potent and (more or less?) toxic than procaine and cocaine.

A

More

More

81
Q

Lidocaine

  • Used in _______, ________ blocks, _____ and _______ anesthesia
    –
    – Has anti-_________ properties
    – Has a (slower or faster?) onset and duration of action than procaine.
A

infiltration, regional nerve blocks, spinal and topical anesthesia

anti-arrhythmic properties

faster

82
Q

Most commonly used Local anesthetic is ???

A

Lidocaine

83
Q

Bupivacaine

– Has particularly (short or long?) duration of action; ______
– Often used for _________________________
– Also used for _______ anaesthesia in obstetrics
– Can be combined with ________

A

long ; 24 hrs

post- operative analgesia.

epidural anaesthesia

Epinephrine

84
Q

Most potent local anaesthetic agent is ????

A

Bupivacaine

85
Q

Ropivacaine

– Recently developed (short or long?) -acting _____-linked local anesthetic.

– Its primary advantage over bupivacaine is its lesser degree of __________.

A

long ; amide

cardiotoxicity.

86
Q

Ropivacaine

Its duration of action is similar to that of _________, but it is slightly (more or less?) potent and requires (lesser or higher?) concentrations to achieve the same degree of block.

A

bupivacaine

Less

Higher

87
Q

Etidocaine
– Chemically similar to ________
– Has a (more or less?) prolonged action than lidocaine
– Used for ________ blocks, including ________ anesthesia.
– Its use in ________ is limited
– Can be combined with ________.

A

lidocaine; more

regional ;epidural

obstetrics ;epinephrine.

88
Q

Mepivacaine
– (Shorter or Longer?) acting than lidocaine
– Has a more (gradual or rapid?) onset of action (—————).
– _________ application is not effective.

A

Longer

rapid ;3–5 minutes

Topical

89
Q

Mepivacaine

– It has been widely used in _________, but its use has declined recently because of the ____________________________ effects it produces.
– It can be used with _______ or _______ (_____ use only).

A

obstetrics

early transient neurobehavioral

epinephrine or levonordefrin

dental

90
Q

Prilocaine
– Onset of action is slightly (shorter or longer?) than that of lidocaine
– Duration of action is ________.
– Prilocaine is 40% (more or less?) toxic acutely than lidocaine
– Suitable for _______ anesthetia
– Metabolized by the ____ to ________,
– Metabolite can cause _____________.

A

longer ; comparable.

less ; regional anesthetia

liver ; orthotoluidine

METHAEMOGLOBINEMIA.

91
Q

ADVERSE EFFECT :Specific

– Procaine
——————— ————-

– Prilocaine
________________

A

Eczematoid dermatitis

Methaemoglobinaemia

92
Q

General adverse effect

Cardiovascular
Vaso____ (except _______)
_____tension
_______arrhythmia

A

dilation

Cocaine

Hypo

Brady

House Pharmacology (50 decks)

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