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Transcript of Chapter 9: Local Anesthetics Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All...
Chapter 9:Chapter 9:
Local AnestheticsLocal Anesthetics
Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
22Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Chapter 9 OutlineChapter 9 Outline HistoryHistory
Ideal local anestheticIdeal local anesthetic ChemistryChemistry Mechanism of actionMechanism of action PharmacokineticsPharmacokinetics Pharmacologic effectsPharmacologic effects Adverse reactionsAdverse reactions Compositions of local anesthetic solutionsCompositions of local anesthetic solutions Local anesthetic agentsLocal anesthetic agents VasoconstrictorsVasoconstrictors Choice of local anestheticChoice of local anesthetic Topical anestheticsTopical anesthetics Doses of local anesthetic and vasoconstrictorDoses of local anesthetic and vasoconstrictor
33Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local AnestheticsLocal Anesthetics
Haveles (p. 112)Haveles (p. 112) No drugs are used more often in the dental No drugs are used more often in the dental
office than local anesthetic agentsoffice than local anesthetic agents Use can become routine, but these agents have a Use can become routine, but these agents have a
potential for systemic effects in addition to desired potential for systemic effects in addition to desired local effectslocal effects
44Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
HistoryHistory
Haveles (p. 112) (Figs. 9-1, 9-2)Haveles (p. 112) (Figs. 9-1, 9-2) ““Painless” dentistry through use of a local Painless” dentistry through use of a local
anesthetic is a relatively recent developmentanesthetic is a relatively recent development Indigenous South American people chewed leaves Indigenous South American people chewed leaves
that made them feel betterthat made them feel better Tasting it produced not only a loss of taste, but Tasting it produced not only a loss of taste, but
also of the sensation of painalso of the sensation of pain
cont’d…cont’d…
55Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
HistoryHistory
Koller noticed that cocaine in the eye Koller noticed that cocaine in the eye produced complete anesthesiaproduced complete anesthesia
Sigmund Freud was also experimenting with Sigmund Freud was also experimenting with cocaine and its effects on the central nervous cocaine and its effects on the central nervous system (CNS)system (CNS) CNS stimulation, toxicity, and the potential for CNS stimulation, toxicity, and the potential for
abuse were quickly recognized as major problems abuse were quickly recognized as major problems with the widespread use of cocaine as a local with the widespread use of cocaine as a local anestheticanesthetic
cont’d…cont’d…
66Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
HistoryHistory
Einhorn synthesized procaine in 1905; many Einhorn synthesized procaine in 1905; many years later, its use became common in years later, its use became common in dentistrydentistry
The amide lidocaine (Xylocaine) was The amide lidocaine (Xylocaine) was released in 1952released in 1952
mepivacaine (Carbocaine) was released in mepivacaine (Carbocaine) was released in 19601960
More recently, bupivacaine (Marcaine) has More recently, bupivacaine (Marcaine) has been made available for dental usebeen made available for dental use
77Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Ideal Local AnestheticIdeal Local Anesthetic
Haveles (pp. 112-113)Haveles (pp. 112-113) Many local anesthetic agents are not clinically Many local anesthetic agents are not clinically
acceptableacceptable The ideal local anesthetic should possess certain The ideal local anesthetic should possess certain
propertiesproperties No local anesthetic in use today meets all of those No local anesthetic in use today meets all of those
requirements, although many acceptable agents requirements, although many acceptable agents are availableare available
88Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Properties of the Ideal Local Properties of the Ideal Local AnestheticAnesthetic
Haveles (p. 113) (Box 9-1)Haveles (p. 113) (Box 9-1) Potent local anesthesiaPotent local anesthesia Reversible local anesthesiaReversible local anesthesia Absence of local reactionsAbsence of local reactions Absence of allergic reactionsAbsence of allergic reactions Rapid onsetRapid onset Satisfactory durationSatisfactory duration Adequate tissue penetrationAdequate tissue penetration Low costLow cost Stability in solution Stability in solution Sterilization by autoclaveSterilization by autoclave Ease of metabolism and excretionEase of metabolism and excretion
99Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
ChemistryChemistry
Haveles (pp. 113-114) (Table 9-1)Haveles (pp. 113-114) (Table 9-1) Local anesthetic agents are divided chemically Local anesthetic agents are divided chemically
into two major groups—amides and estersinto two major groups—amides and esters A few agents fall outside these two groupsA few agents fall outside these two groups
The importance of this division is associated The importance of this division is associated with potential allergic reactionswith potential allergic reactions Cross-hypersensitivity between amides and esters Cross-hypersensitivity between amides and esters
is unlikely is unlikely
cont’d…cont’d…
1010Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
ChemistryChemistry
The structure of local anesthetic is composed The structure of local anesthetic is composed of the following three partsof the following three parts Aromatic nucleus (R)Aromatic nucleus (R) Linkage (either an ester or amide, followed by an Linkage (either an ester or amide, followed by an
aliphatic chain, R)aliphatic chain, R) Amino groupAmino group
The aromatic nucleus (R) is lipophilic and the The aromatic nucleus (R) is lipophilic and the amino group is hydrophilicamino group is hydrophilic
Esters are largely metabolized in the plasma Esters are largely metabolized in the plasma and amides in the liverand amides in the liver
1111Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action Haveles (pp. 113-115) (Fig. 9-3; Box 9-2)Haveles (pp. 113-115) (Fig. 9-3; Box 9-2)
Action on nerve fibersAction on nerve fibers A resting nerve fiber has a large number of positive ions on A resting nerve fiber has a large number of positive ions on
the outside and a large number of negative ions on the the outside and a large number of negative ions on the insideinside
The nerve action potential results in the opening of The nerve action potential results in the opening of sodium channels and in inward flux of sodiumsodium channels and in inward flux of sodium This results in a change from the –90-mV potential to a This results in a change from the –90-mV potential to a
+40-mV potential+40-mV potential The outward flow of potassium ions repolarizes the The outward flow of potassium ions repolarizes the
membrane and closes the sodium channelsmembrane and closes the sodium channelscont’d…cont’d…
1212Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action
Haveles (p. 114)Haveles (p. 114) Action on nerve fibersAction on nerve fibers
Local anesthetics attach themselves to specific Local anesthetics attach themselves to specific receptors in the nerve membranereceptors in the nerve membrane
After combining with the receptor, local After combining with the receptor, local anesthetics block conduction of nerve impulses by anesthetics block conduction of nerve impulses by decreasing the permeability of the nerve cell decreasing the permeability of the nerve cell membrane to sodium ionsmembrane to sodium ions
cont’d…cont’d…
1313Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action
Decreasing permeability to sodium ions Decreasing permeability to sodium ions Decreases the rate of depolarization of the nerve Decreases the rate of depolarization of the nerve
membranemembrane Increases the threshold for excitabilityIncreases the threshold for excitability Prevents propagation of the action potentialPrevents propagation of the action potential
Local anesthetics may reduce permeability by Local anesthetics may reduce permeability by competing with calcium for the membrane competing with calcium for the membrane binding sites and by preventing the onset of binding sites and by preventing the onset of nerve conductionnerve conduction
cont’d…cont’d…
1414Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action
Haveles (pp. 114-115) (Fig. 9-4)Haveles (pp. 114-115) (Fig. 9-4) Ionization factorsIonization factors
Local anesthetic agents are weak bases occurring Local anesthetic agents are weak bases occurring equilibrated between equilibrated between • Fat-soluble (lipophilic) free baseFat-soluble (lipophilic) free base
• Water-soluble (hydrophilic) hydrochloride saltWater-soluble (hydrophilic) hydrochloride salt
The proportion in each form is determined byThe proportion in each form is determined by• The acid dissociation constant (pKa) of the local The acid dissociation constant (pKa) of the local
anestheticanesthetic
• The pH of the environmentThe pH of the environment
cont’d…cont’d…
1515Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action
In the acidic pH of the dental cartridge (4.5), In the acidic pH of the dental cartridge (4.5), the proportion of the drug in the ionized form the proportion of the drug in the ionized form increases, increasing solubilityincreases, increasing solubility Once injected into tissues (pH 7.4), the amount of Once injected into tissues (pH 7.4), the amount of
local anesthetic in the free-base form increaseslocal anesthetic in the free-base form increases This provides for greater tissue (lipid) penetrationThis provides for greater tissue (lipid) penetration
cont’d…cont’d…
1616Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Mechanism of ActionMechanism of Action
In an acidic environment such as infection or In an acidic environment such as infection or inflammation (pH lower), the amount of free inflammation (pH lower), the amount of free base is reduced (more in ionized form)base is reduced (more in ionized form) This is one reason dental anesthesia with a local This is one reason dental anesthesia with a local
anesthetic is more difficult when infection is presentanesthetic is more difficult when infection is present Other reasons include dilution by fluid, Other reasons include dilution by fluid,
inflammation, and vasodilation in the areainflammation, and vasodilation in the area The free base form is needed to penetrate the The free base form is needed to penetrate the
nerve membranenerve membrane The cationic form exerts blocking action by binding The cationic form exerts blocking action by binding
to the specific receptor siteto the specific receptor site
1717Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 112)Haveles (p. 112) Absorption depends on its routeAbsorption depends on its route
When injected into tissues the rate depends on the When injected into tissues the rate depends on the vascularity of the tissuesvascularity of the tissues• This is a function of the degree of inflammation present, This is a function of the degree of inflammation present,
the vasodilating properties of the local anesthetic agent, the vasodilating properties of the local anesthetic agent, the presence of heat, or use of massagethe presence of heat, or use of massage
cont’d…cont’d…
1818Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 112)Haveles (p. 112) AbsorptionAbsorption
Reducing the systemic absorption of a Reducing the systemic absorption of a local anesthetic is important when it is local anesthetic is important when it is used in dentistryused in dentistry• With reduced absorption, the chance of With reduced absorption, the chance of
systemic toxicity is reducedsystemic toxicity is reduced
cont’d…cont’d…
1919Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
A vasoconstrictor is added to the local A vasoconstrictor is added to the local anesthetic to reduce absorptionanesthetic to reduce absorption
The vasoconstrictorThe vasoconstrictor Reduces the blood supply to the areaReduces the blood supply to the area Limits systemic absorptionLimits systemic absorption Reduces systemic toxicityReduces systemic toxicity
cont’d…cont’d…
2020Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 112)Haveles (p. 112) AbsorptionAbsorption
With topical application, especially on mucous With topical application, especially on mucous membranes or if the surface is denuded, membranes or if the surface is denuded, absorption can approximate that produced by absorption can approximate that produced by intravenous injectionintravenous injection
It is also determined by the proportion of the agent It is also determined by the proportion of the agent present in the free-base form (nonionized)present in the free-base form (nonionized)
cont’d…cont’d…
2121Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 115)Haveles (p. 115) DistributionDistribution
After absorption, local anesthetics are distributed After absorption, local anesthetics are distributed throughout the bodythroughout the body• Highly vascular organs have higher concentrations of Highly vascular organs have higher concentrations of
anestheticsanesthetics
Local anesthetics cross the placenta and blood-Local anesthetics cross the placenta and blood-brain barrierbrain barrier• Lipid solubility affects the potency of the agentLipid solubility affects the potency of the agent
• Bupivacaine 0.5% is about 10 times more lipid soluble Bupivacaine 0.5% is about 10 times more lipid soluble than lidocaine used as a 2% solutionthan lidocaine used as a 2% solution
cont’d…cont’d…
2222Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 115)Haveles (p. 115) MetabolismMetabolism
Local anesthetic agents are metabolized Local anesthetic agents are metabolized differently, depending on whether they are amides differently, depending on whether they are amides or estersor esters• Esters are hydrolyzed by plasma pseudocholinesterases Esters are hydrolyzed by plasma pseudocholinesterases
and liver esterasesand liver esterases
• Procaine is hydrolyzed to para-aminobenzoic acid Procaine is hydrolyzed to para-aminobenzoic acid (PABA), a metabolite that may be responsible for its (PABA), a metabolite that may be responsible for its allergic reactionallergic reaction
cont’d…cont’d…
2323Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 115)Haveles (p. 115) MetabolismMetabolism
Amide local anesthetics are metabolized primarily by Amide local anesthetics are metabolized primarily by the liverthe liver• In severe liver disease or with alcoholism, amides may In severe liver disease or with alcoholism, amides may
accumulate and produce systemic toxicityaccumulate and produce systemic toxicity
A small amount of prilocaine is metabolized to A small amount of prilocaine is metabolized to orthotoluidine, which can produce orthotoluidine, which can produce methemoglobinemia if given in very large dosesmethemoglobinemia if given in very large doses
Cimetidine can interfere with metabolism of amides Cimetidine can interfere with metabolism of amides by reducing hepatic blood flowby reducing hepatic blood flow
cont’d…cont’d…
2424Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
PharmacokineticsPharmacokinetics
Haveles (p. 115)Haveles (p. 115) ExcretionExcretion
Metabolites and some unchanged drug of both Metabolites and some unchanged drug of both esters and amides are excreted by the kidneysesters and amides are excreted by the kidneys
Both parent drug and metabolites can accumulate Both parent drug and metabolites can accumulate with end-stage renal diseasewith end-stage renal disease
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Pharmacologic EffectsPharmacologic Effects
Haveles (pp. 115-116)Haveles (pp. 115-116) Peripheral nerve conduction (blocker)Peripheral nerve conduction (blocker)
The main clinical effect of local anesthetic is The main clinical effect of local anesthetic is reversible blockage of peripheral nerve conductionreversible blockage of peripheral nerve conduction• These agents inhibit movement of the nerve impulse along These agents inhibit movement of the nerve impulse along
the fibers, at sensory endings, at myoneural junctions, and the fibers, at sensory endings, at myoneural junctions, and at synapsesat synapses
They do not penetrate the myelin sheath, but they They do not penetrate the myelin sheath, but they affect myelinated fibers only at the nodes of Ranvieraffect myelinated fibers only at the nodes of Ranvier
Local anesthetics affect small, unmyelinated fibers Local anesthetics affect small, unmyelinated fibers first and large; heavily myelinated fibers lastfirst and large; heavily myelinated fibers last
2626Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Common Order of Nerve Common Order of Nerve Function LossFunction Loss
Haveles (p. 116) (Box 9-3)Haveles (p. 116) (Box 9-3) AutonomicAutonomic ColdCold WarmthWarmth PainPain TouchTouch PressurePressure VibrationVibration ProprioceptionProprioception MotorMotor
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Pharmacologic EffectsPharmacologic Effects
Haveles (pp. 115-116)Haveles (pp. 115-116) AntiarrhythmicAntiarrhythmic
Local anesthetics have a direct effect on cardiac Local anesthetics have a direct effect on cardiac muscle by blocking cardiac sodium channels and muscle by blocking cardiac sodium channels and depressing abnormal cardiac pacemaker activity, depressing abnormal cardiac pacemaker activity, excitability, and conductionexcitability, and conduction• They also depress strength of cardiac contraction and They also depress strength of cardiac contraction and
produce arteriolar dilation, leading to hypotensionproduce arteriolar dilation, leading to hypotension
These properties make than useful in treatment of These properties make than useful in treatment of arrhythmiasarrhythmias
2828Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (p. 116) (Table 9-2)Haveles (p. 116) (Table 9-2) ToxicityToxicity
Adverse reactions and toxicity are directly related Adverse reactions and toxicity are directly related to the plasma level of the drugto the plasma level of the drug• Their potential for danger must be minimalTheir potential for danger must be minimal
• Deaths from local anesthetics are difficult to document, Deaths from local anesthetics are difficult to document, dental-related mortality is even rarerdental-related mortality is even rarer
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
Factors influencing toxicity includeFactors influencing toxicity include Drug: inherent toxicity and amount of vasodilationDrug: inherent toxicity and amount of vasodilation Concentration Concentration Route of administrationRoute of administration Rate of injectionRate of injection VascularityVascularity Patient’s weightPatient’s weight Rate of metabolism and excretionRate of metabolism and excretion
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
Haveles (p. 116)Haveles (p. 116) ToxicityToxicity
CNS effectsCNS effects CNS stimulation may occur before CNS CNS stimulation may occur before CNS
depressiondepression• CNS stimulation caused by depression of inhibitory fibers CNS stimulation caused by depression of inhibitory fibers
results in restlessness, tremors, and convulsionsresults in restlessness, tremors, and convulsions
• CNS depression caused by depression of both inhibitory CNS depression caused by depression of both inhibitory and facilitative fibers results in respiratory and and facilitative fibers results in respiratory and cardiovascular depression, and coma followscardiovascular depression, and coma follows
cont’d…cont’d…
3131Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (pp. 116-117)Haveles (pp. 116-117) ToxicityToxicity
Cardiovascular effectsCardiovascular effects• Local anesthetic agents can produce myocardial Local anesthetic agents can produce myocardial
depression and cardiac arrest with peripheral vasodilationdepression and cardiac arrest with peripheral vasodilation
• Usual concentrations that are achieved with administration Usual concentrations that are achieved with administration of dental anesthesia would not be expected to result in of dental anesthesia would not be expected to result in any of these adverse reactionsany of these adverse reactions
• It is postulated that the effect of these agents on heart It is postulated that the effect of these agents on heart conduction may produce a fatal arrhythmiaconduction may produce a fatal arrhythmia
cont’d…cont’d…
3232Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (pp. 116-117)Haveles (pp. 116-117) Local effectsLocal effects
Most commonly the result of physical injury Most commonly the result of physical injury caused by injection technique or administration of caused by injection technique or administration of an excessive volume too quickly to be accepted by an excessive volume too quickly to be accepted by the tissuesthe tissues
Occasionally a hematoma may be producedOccasionally a hematoma may be produced
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
Haveles (p. 117)Haveles (p. 117) Malignant hyperthermiaMalignant hyperthermia
An inherited disease that is transmitted as an An inherited disease that is transmitted as an autosomal-dominant gene with reduced penetration autosomal-dominant gene with reduced penetration and variable expressionand variable expression
Symptoms include an acute rise in calcium, which Symptoms include an acute rise in calcium, which produces muscular rigidity, metabolic acidosis, and produces muscular rigidity, metabolic acidosis, and extremely high feverextremely high fever• Mortality is above 50%Mortality is above 50%
Treatment includes supportive measures and the Treatment includes supportive measures and the administration of dantroleneadministration of dantrolene
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
In the past, it was thought that amide local In the past, it was thought that amide local anesthetics might precipitate malignant anesthetics might precipitate malignant hyperthermia, but they are currently no longer hyperthermia, but they are currently no longer implicatedimplicated Patients with a family history of malignant Patients with a family history of malignant
hyperthermia can be given amide local anesthetic hyperthermia can be given amide local anesthetic agentsagents
cont’d…cont’d…
3535Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (p. 117)Haveles (p. 117) Pregnancy and nursing considerationsPregnancy and nursing considerations
Elective dental treatment should be rendered Elective dental treatment should be rendered before a patient becomes pregnantbefore a patient becomes pregnant
Most sources suggest that lidocaine may be Most sources suggest that lidocaine may be administered to a pregnant woman if dental administered to a pregnant woman if dental treatment is neededtreatment is needed
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
Pregnancy and nursing considerationsPregnancy and nursing considerations Fetal bradycardia has been reported when larger Fetal bradycardia has been reported when larger
doses are administered to the mother near termdoses are administered to the mother near term• Lidocaine and prilocaine are U.S. Food and Drug Lidocaine and prilocaine are U.S. Food and Drug
Administration (FDA) pregnancy category BAdministration (FDA) pregnancy category B
• Mepivacaine, articaine, and bupivacaine are FDA Mepivacaine, articaine, and bupivacaine are FDA pregnancy category Cpregnancy category C
cont’d…cont’d…
3737Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (p. 117)Haveles (p. 117) AllergyAllergy
Allergic reactions that result from local anesthetics Allergic reactions that result from local anesthetics have been reportedhave been reported• They range from rash to anaphylactic shockThey range from rash to anaphylactic shock
An allergy history should be elicited from each An allergy history should be elicited from each patient before a local anesthetic agent is chosenpatient before a local anesthetic agent is chosen
Esters have a much greater allergic potential; Esters have a much greater allergic potential; some question has surfaced about whether some question has surfaced about whether amides can produce allergic reactions at allamides can produce allergic reactions at all
cont’d…cont’d…
3838Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Adverse ReactionsAdverse Reactions
Haveles (p. 117)Haveles (p. 117) AllergyAllergy
Patients giving a history of allergies to all local Patients giving a history of allergies to all local anesthetic agents may be “tested” by giving them anesthetic agents may be “tested” by giving them an amide by injectionan amide by injection
Use of skin testing is unreliable; it can give both Use of skin testing is unreliable; it can give both false-positive and false-negative resultsfalse-positive and false-negative results
cont’d…cont’d…
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Adverse ReactionsAdverse Reactions
Haveles (p. 117)Haveles (p. 117) AllergyAllergy
Another approach is to use the antihistamine Another approach is to use the antihistamine diphenhydramine (Benadryl) as a local anestheticdiphenhydramine (Benadryl) as a local anesthetic
Antihistamines, because of their similarity in Antihistamines, because of their similarity in structure to local anesthetics, have some local structure to local anesthetics, have some local anesthetic actionanesthetic action
diphenhydramine (Benadryl) in a concentration of diphenhydramine (Benadryl) in a concentration of 1% plus 1:100,000 epinephrine is recommended to 1% plus 1:100,000 epinephrine is recommended to be given by injection to produce a blockbe given by injection to produce a block• No prepared product is available; this combination must be No prepared product is available; this combination must be
prepared from its constituentsprepared from its constituentscont’d…cont’d…
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Adverse ReactionsAdverse Reactions
AllergyAllergy Local anesthetics with vasoconstrictors also Local anesthetics with vasoconstrictors also
contain a sulfite that serves as an antioxidantcontain a sulfite that serves as an antioxidant• In sulfite-sensitive patients, the sulfites may produce a In sulfite-sensitive patients, the sulfites may produce a
hypersensitivity reaction that exhibits itself as an acute hypersensitivity reaction that exhibits itself as an acute asthmatic attackasthmatic attack
• The reaction is the same as the “salad bar” syndrome, a The reaction is the same as the “salad bar” syndrome, a hypersensitivity reaction to sulfiteshypersensitivity reaction to sulfites
4141Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Composition of Local Anesthetic Composition of Local Anesthetic SolutionsSolutions
Haveles (pp. 117-118)Haveles (pp. 117-118) Local anesthetic usually contains several other Local anesthetic usually contains several other
ingredients such as the followingingredients such as the following Vasoconstrictor: to retard absorption, reduce Vasoconstrictor: to retard absorption, reduce
systemic toxicity, and prolong duration of actionsystemic toxicity, and prolong duration of action Antioxidant: to retard oxidation of epinephrineAntioxidant: to retard oxidation of epinephrine Sodium hydroxide: to adjust the pH between 6 and 7Sodium hydroxide: to adjust the pH between 6 and 7 Methylparaben and propylparaben: preservatives Methylparaben and propylparaben: preservatives
added to multidose parenteral solutionsadded to multidose parenteral solutions• No dental cartridge contains methylparabenNo dental cartridge contains methylparaben
4242Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 118)Haveles (p. 118) AmidesAmides
Many local anesthetic agents are available with Many local anesthetic agents are available with similar pharmacologic and clinical effects and similar pharmacologic and clinical effects and systemic toxicitysystemic toxicity• Dental issues associated with local anesthetics are listed Dental issues associated with local anesthetics are listed
in Box 9-4in Box 9-4
• Table 9-3 lists the local anesthetics available in dental Table 9-3 lists the local anesthetics available in dental cartridgescartridges
cont’d…cont’d…
4343Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 118)Haveles (p. 118) AmidesAmides
The only class of anesthetics used parenterallyThe only class of anesthetics used parenterally• Esters are occasionally used topicallyEsters are occasionally used topically
• The relative lack of allergenicity of the amides is The relative lack of allergenicity of the amides is probably responsible for thisprobably responsible for this
cont’d…cont’d…
4444Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (pp. 118-120)Haveles (pp. 118-120) Amides: lidocaineAmides: lidocaine
Introduced in 1948, it became an anesthetic Introduced in 1948, it became an anesthetic standard to which other local anesthetics were standard to which other local anesthetics were comparedcompared
Rapid onset related to its tendency to spread well Rapid onset related to its tendency to spread well through the tissuesthrough the tissues
Lidocaine 2% with vasoconstrictor provides profound Lidocaine 2% with vasoconstrictor provides profound anesthesia of medium durationanesthesia of medium duration• The local anesthetic solution most commonly used in The local anesthetic solution most commonly used in
dental officesdental officescont’d…cont’d…
4545Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 118) (Fig. 9-5)Haveles (p. 118) (Fig. 9-5) Amides: lidocaineAmides: lidocaine
No cross-allergenicity among the amide lidocaine, No cross-allergenicity among the amide lidocaine, other available amides, or esters has been other available amides, or esters has been documenteddocumented
In toxic reactions, one is likely to observe CNS In toxic reactions, one is likely to observe CNS depression initially rather than the CNS stimulation depression initially rather than the CNS stimulation characteristic of other local anestheticscharacteristic of other local anesthetics
Adverse reactions include hypotension, positional Adverse reactions include hypotension, positional headache, and shiveringheadache, and shivering
cont’d…cont’d…
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Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: lidocaineAmides: lidocaine
In dentistry, lidocaine 2% with 1:100,000 In dentistry, lidocaine 2% with 1:100,000 epinephrine is used for infiltration and block epinephrine is used for infiltration and block anesthesiaanesthesia• Lidocaine is used for topical anesthesia as a 5% ointment, Lidocaine is used for topical anesthesia as a 5% ointment,
a 10% spray, and a 2% viscous solutiona 10% spray, and a 2% viscous solution
Lidocaine with epinephrine 1:100,000 provides a Lidocaine with epinephrine 1:100,000 provides a 1.0- to 1.5-hour duration of pulpal anesthesia1.0- to 1.5-hour duration of pulpal anesthesia• Soft-tissue anesthesia is maintained for 3 to 4 hoursSoft-tissue anesthesia is maintained for 3 to 4 hours
cont’d…cont’d…
4747Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: lidocaineAmides: lidocaine
A new dose form of lidocaine is a patch applied to A new dose form of lidocaine is a patch applied to mucosal membranes for local anesthesiamucosal membranes for local anesthesia
Its maximal effect occurs after about 10 minutes, Its maximal effect occurs after about 10 minutes, which is probably too long to waitwhich is probably too long to wait
cont’d…cont’d…
4848Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: mepivacaineAmides: mepivacaine
Introduced in 1960, its rate of onset, duration, Introduced in 1960, its rate of onset, duration, potency, and toxicity are similar to those of lidocainepotency, and toxicity are similar to those of lidocaine
Mepivacaine is not effective topically; however, it is Mepivacaine is not effective topically; however, it is used for infiltration, block, spinal, epidural, and used for infiltration, block, spinal, epidural, and caudal anesthesiacaudal anesthesia
The usual dose form in dentistry is a 2% solution The usual dose form in dentistry is a 2% solution with addition of 1:20,000 levonordephrin (Neo-with addition of 1:20,000 levonordephrin (Neo-Cobefrin) as a vasoconstrictorCobefrin) as a vasoconstrictor
cont’d…cont’d…
4949Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: mepivacaineAmides: mepivacaine
Because mepivacaine produces less vasodilation Because mepivacaine produces less vasodilation than lidocaine, it can be used as a 3% solution than lidocaine, it can be used as a 3% solution without a vasoconstrictor without a vasoconstrictor
Can be used for short procedures when a Can be used for short procedures when a vasoconstrictor is contraindicatedvasoconstrictor is contraindicated
cont’d…cont’d…
5050Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: prilocaineAmides: prilocaine
Prilocaine is related chemically and Prilocaine is related chemically and pharmacologically to both lidocaine and mepivacainepharmacologically to both lidocaine and mepivacaine
Chemically, lidocaine and mepivacaine are xylidine Chemically, lidocaine and mepivacaine are xylidine derivatives, whereas prilocaine is a toluidine derivatives, whereas prilocaine is a toluidine derivativederivative
Prilocaine appears to be less potent and less toxic Prilocaine appears to be less potent and less toxic than lidocaine and has a slightly longer duration of than lidocaine and has a slightly longer duration of actionaction
cont’d…cont’d…
5151Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: prilocaineAmides: prilocaine
Although toxicity of prilocaine is 60% that occurring Although toxicity of prilocaine is 60% that occurring with lidocaine, several cases of methemoglobinemia with lidocaine, several cases of methemoglobinemia have been reported after its usehave been reported after its use
Prilocaine is metabolized to orthotoluidine and in Prilocaine is metabolized to orthotoluidine and in large doses can induce some methemoglobinemialarge doses can induce some methemoglobinemia
Prilocaine should not be administered to patients Prilocaine should not be administered to patients with any condition in which problems of oxygenation with any condition in which problems of oxygenation may be especially criticalmay be especially critical
cont’d…cont’d…
5252Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: prilocaineAmides: prilocaine
Drugs that affect the hemoglobin, such as Drugs that affect the hemoglobin, such as acetaminophen, may exacerbate the adverse acetaminophen, may exacerbate the adverse reactionreaction
Prilocaine is used for infiltration, block, epidural, Prilocaine is used for infiltration, block, epidural, and caudal anesthesiaand caudal anesthesia
It is available in dental cartridges as a 4% It is available in dental cartridges as a 4% concentration both with and without 1:200,000 concentration both with and without 1:200,000 epinephrineepinephrine
cont’d…cont’d…
5353Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents Haveles (p. 119)Haveles (p. 119)
Amides: prilocaineAmides: prilocaine Prilocaine’s niche in dentistry involves situations in which Prilocaine’s niche in dentistry involves situations in which
the desired duration of action is somewhat longer than the desired duration of action is somewhat longer than that obtained with mepivacaine both without and with that obtained with mepivacaine both without and with vasoconstrictorvasoconstrictor
Prilocaine plain has a duration of action slightly longer Prilocaine plain has a duration of action slightly longer than mepivacaine plain, and prilocaine with epinephrine than mepivacaine plain, and prilocaine with epinephrine has a duration of action slightly longer than lidocaine has a duration of action slightly longer than lidocaine with epinephrinewith epinephrine
The other potential advantage of prilocaine is that the The other potential advantage of prilocaine is that the concentration of epinephrine (1:200,000) is lower than in concentration of epinephrine (1:200,000) is lower than in other local anesthetic amide combinationsother local anesthetic amide combinations
cont’d…cont’d…
5454Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: bupivacaineAmides: bupivacaine
Bupivacaine is related to lidocaine and mepivacaineBupivacaine is related to lidocaine and mepivacaine More potent but less toxic than the other amidesMore potent but less toxic than the other amides The major advantage is its greatly prolonged The major advantage is its greatly prolonged
duration of actionduration of action Indicated in lengthy dental procedures when pulpal Indicated in lengthy dental procedures when pulpal
anesthesia of greater than 1.5 hours is needed or anesthesia of greater than 1.5 hours is needed or when postoperative pain is expectedwhen postoperative pain is expected
cont’d…cont’d…
5555Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: bupivacaineAmides: bupivacaine
Available in dental cartridges as a 0.5% solution Available in dental cartridges as a 0.5% solution with 1:200,000 epinephrinewith 1:200,000 epinephrine
Should not be used in patients prone to self-Should not be used in patients prone to self-mutilationmutilation
Bupivacaine has been used for infiltration, block, Bupivacaine has been used for infiltration, block, and peridural anesthesiaand peridural anesthesia
cont’d…cont’d…
5656Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: articaineAmides: articaine
Articaine was approved for use in the United States in Articaine was approved for use in the United States in 20002000• Its delay in the United States was a result of the addition of Its delay in the United States was a result of the addition of
methylparaben to both multidose vials and single-dose methylparaben to both multidose vials and single-dose cartridgescartridges
Articaine is derived from thiopheneArticaine is derived from thiophene• This allows for greater lipid solubility and ability to cross lipid This allows for greater lipid solubility and ability to cross lipid
barriers such as nerve membranesbarriers such as nerve membranes
• This mechanism may account for its enhanced action This mechanism may account for its enhanced action compared with other local anestheticscompared with other local anesthetics
cont’d…cont’d…
5757Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 119)Haveles (p. 119) Amides: articaineAmides: articaine
Articaine also differs from other amide local Articaine also differs from other amide local anesthetics because it has an extra ester linkageanesthetics because it has an extra ester linkage• This extra linkage causes articaine to be hydrolyzed by This extra linkage causes articaine to be hydrolyzed by
plasma esteraseplasma esterase
• Only 5% to 10% of articaine is metabolized by the liver; Only 5% to 10% of articaine is metabolized by the liver; the other 90% to 95% is metabolized in the bloodthe other 90% to 95% is metabolized in the blood
cont’d…cont’d…
5858Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) Amides: articaineAmides: articaine
Articaine is excreted by the kidneysArticaine is excreted by the kidneys The average patient can tolerate twice as much The average patient can tolerate twice as much
lidocaine as compared with articaine before the lidocaine as compared with articaine before the maximal dose is reachedmaximal dose is reached
Articaine, similar to prilocaine, may cause Articaine, similar to prilocaine, may cause methemoglobinemia in very high dosesmethemoglobinemia in very high doses
Articaine rarely causes paresthesia after a mandibular Articaine rarely causes paresthesia after a mandibular block when the 4% solution is usedblock when the 4% solution is used
cont’d…cont’d…
5959Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) Amides: articaineAmides: articaine
Articaine is used for local, infiltrative, and Articaine is used for local, infiltrative, and conductive anesthesiaconductive anesthesia
Available as a 4% concentration with 1:100,000 Available as a 4% concentration with 1:100,000 epinephrine in a 1.7 ml cartridge unlike the more epinephrine in a 1.7 ml cartridge unlike the more common 1.8 ml dental cartridgecommon 1.8 ml dental cartridge
cont’d…cont’d…
6060Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) EstersEsters
No esters are currently available in a dental No esters are currently available in a dental cartridgecartridge
Esters, such as benzocaine, are commonly used Esters, such as benzocaine, are commonly used topicallytopically
cont’d…cont’d…
6161Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) Esters: procaineEsters: procaine
Procaine is a PABA esterProcaine is a PABA ester Procaine is used as an antiarrhythmic agent and is Procaine is used as an antiarrhythmic agent and is
combined with penicillin to form procaine penicillin Gcombined with penicillin to form procaine penicillin G Procaine is not used in dentistry today because of Procaine is not used in dentistry today because of
the high rate of allergic reactionthe high rate of allergic reaction The allergic reaction is usually a result of PABA and The allergic reaction is usually a result of PABA and
not procainenot procaine
cont’d…cont’d…
6262Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) Esters: propoxycaineEsters: propoxycaine
Propoxycaine, another ester of PABA, is not Propoxycaine, another ester of PABA, is not available in a dental cartridgeavailable in a dental cartridge
cont’d…cont’d…
6363Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Local Anesthetic AgentsLocal Anesthetic Agents
Haveles (p. 120)Haveles (p. 120) Esters: tetracaineEsters: tetracaine
Tetracaine, an ester of PABA, has a slow onset Tetracaine, an ester of PABA, has a slow onset and long duration, and is generally estimated to and long duration, and is generally estimated to have at least 10 times the potency and toxicity of have at least 10 times the potency and toxicity of procaineprocaine
Great care must be exercised if used for topical Great care must be exercised if used for topical anesthesiaanesthesia
Tetracaine is available in various sprays, Tetracaine is available in various sprays, solutions, and ointments for topical applicationsolutions, and ointments for topical application
6464Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Other Local AnestheticsOther Local Anesthetics
Haveles (p. 120)Haveles (p. 120) DyclonineDyclonine
Dyclonine is a topical local anesthetic that is Dyclonine is a topical local anesthetic that is neither an ester nor an amideneither an ester nor an amide
Its side effects involving the cardiovascular system Its side effects involving the cardiovascular system and CNS are similar to those of the other local and CNS are similar to those of the other local anestheticsanesthetics
The onset of local anesthesia is 2 to 10 minutes, The onset of local anesthesia is 2 to 10 minutes, and its duration is 30 to 60 minutesand its duration is 30 to 60 minutes
cont’d…cont’d…
6565Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Other Local AnestheticsOther Local Anesthetics
Haveles (p. 120)Haveles (p. 120) BenzonatateBenzonatate
Benzonatate is a tetracaine congener indicated in Benzonatate is a tetracaine congener indicated in the management of nonproductive coughthe management of nonproductive cough
A topical anesthetic that acts on the respiratory A topical anesthetic that acts on the respiratory stretch receptors, which produces its antitussive stretch receptors, which produces its antitussive propertiesproperties
6666Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors Haveles (p. 120) (Box 9-5)Haveles (p. 120) (Box 9-5)
OverviewOverview Vasoconstricting agents are included in local anesthetic Vasoconstricting agents are included in local anesthetic
solutions for many reasonssolutions for many reasons• Vasoconstrictors are members of the autonomic nervous system Vasoconstrictors are members of the autonomic nervous system
drugs call the adrenergic agonists or sympathomimeticsdrugs call the adrenergic agonists or sympathomimetics
• When a local anesthetic solution does not contain a When a local anesthetic solution does not contain a vasoconstrictor, the anesthetic drug is more quickly removed vasoconstrictor, the anesthetic drug is more quickly removed from the injection site and distributed into systemic circulation from the injection site and distributed into systemic circulation than if the solution contained a vasoconstrictorthan if the solution contained a vasoconstrictor
• Any anesthetic given without a vasoconstrictor is more likely to Any anesthetic given without a vasoconstrictor is more likely to be toxic than those given without a vasoconstrictorbe toxic than those given without a vasoconstrictor
cont’d…cont’d…
6767Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors Haveles (p. 121) (Figs. 9-6, 9-7)Haveles (p. 121) (Figs. 9-6, 9-7)
OverviewOverview The decision about whether epinephrine should be used The decision about whether epinephrine should be used
in a patient is made by weighing the risks and benefitsin a patient is made by weighing the risks and benefits A sufficient concentration must be used to keep the local A sufficient concentration must be used to keep the local
anesthetic localized at its site of action and provide anesthetic localized at its site of action and provide adequate depth, duration, and low systemic toxicity of the adequate depth, duration, and low systemic toxicity of the anestheticanesthetic
1:100,000 and 1:200,000 produce about the same 1:100,000 and 1:200,000 produce about the same amount of vasoconstriction and the same distribution of amount of vasoconstriction and the same distribution of the local anestheticsthe local anesthetics
cont’d…cont’d…
6868Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors Haveles (p. 121) (Fig. 9-7)Haveles (p. 121) (Fig. 9-7)
OverviewOverview Research shows that a patient can produce endogenous Research shows that a patient can produce endogenous
epinephrine far in excess of that administered in dentistry in epinephrine far in excess of that administered in dentistry in the presence of inadequate anesthesia, which sometimes the presence of inadequate anesthesia, which sometimes occurs when vasoconstrictors are avoidedoccurs when vasoconstrictors are avoided
Patients with uncontrolled high blood pressure, Patients with uncontrolled high blood pressure, hyperthyroidism, angina pectoris, and cardiac arrhythmias hyperthyroidism, angina pectoris, and cardiac arrhythmias and those who have had a myocardial infarction or and those who have had a myocardial infarction or cerebrovascular accident in the past 6 months should make cerebrovascular accident in the past 6 months should make an appointment for elective dental treatment after their an appointment for elective dental treatment after their medical condition is under controlmedical condition is under control
cont’d…cont’d…
6969Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors Haveles (p. 122) (Table 9-4)Haveles (p. 122) (Table 9-4)
OverviewOverview Patients with cardiovascular disease who are able to Patients with cardiovascular disease who are able to
withstand elective dental treatment can receive withstand elective dental treatment can receive epinephrine-containing local anesthetic agentsepinephrine-containing local anesthetic agents
Anesthetic should be administered in the lowest Anesthetic should be administered in the lowest possible dose by means of the best technique, possible dose by means of the best technique, including aspiration and a very slow injection rate to including aspiration and a very slow injection rate to minimize systemic absorptionminimize systemic absorption
The maximal safe dose of epinephrine for the healthy The maximal safe dose of epinephrine for the healthy patient is 0.2 mg and for the cardiac patient is 0.04 mgpatient is 0.2 mg and for the cardiac patient is 0.04 mg
cont’d…cont’d…
7070Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors
Haveles (p. 122)Haveles (p. 122) Drug interactionsDrug interactions
The two epinephrine drug interactions that are The two epinephrine drug interactions that are most likely to be clinically significantmost likely to be clinically significant
Tricyclic antidepressantsTricyclic antidepressants• Administration of epinephrine may produce an Administration of epinephrine may produce an
exaggerated increase in pressor responseexaggerated increase in pressor response
Nonselective Nonselective ββ-blockers-blockers• Hypertension and reflex bradycardia may be exhibitedHypertension and reflex bradycardia may be exhibited
cont’d…cont’d…
7171Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
VasoconstrictorsVasoconstrictors Haveles (p. 122)Haveles (p. 122)
Drug interactionsDrug interactions The two drug interactions commonly mentioned but not The two drug interactions commonly mentioned but not
usually clinically significant areusually clinically significant are Monoamine oxidase inhibitors (MAOIs)Monoamine oxidase inhibitors (MAOIs)
Epinephrine can be given to patients taking MAOIs, Epinephrine can be given to patients taking MAOIs, because epinephrine is eliminated primarily by reuptake because epinephrine is eliminated primarily by reuptake and secondarily by catechol-O-methyltransferase and secondarily by catechol-O-methyltransferase (COMT) rather than by monoamine oxidase (MAO)(COMT) rather than by monoamine oxidase (MAO)
Indirect acting sympathomimetic agents should be Indirect acting sympathomimetic agents should be avoided in patients taking MAOIsavoided in patients taking MAOIs
PhenothiazinesPhenothiazines Phenothiazines are Phenothiazines are αα-blockers, and when an -blockers, and when an αα- and - and ββ--
agonist is given, the beta effects predominateagonist is given, the beta effects predominate
7272Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Choice of Local AnestheticChoice of Local Anesthetic Haveles (pp. 122-124) (Figs. 9-8, 9-9; Box 9-6; Table 9-6)Haveles (pp. 122-124) (Figs. 9-8, 9-9; Box 9-6; Table 9-6)
Local anesthetic should be chosen depending on Local anesthetic should be chosen depending on the duration of local anesthesia desired and the the duration of local anesthesia desired and the side effects that must be avoidedside effects that must be avoided pKa is related to duration of actionpKa is related to duration of action
• With lower pKa, the local anesthetic is distributed more in the With lower pKa, the local anesthetic is distributed more in the base form and so is better absorbedbase form and so is better absorbed
Duration of action is primarily related to its protein-binding Duration of action is primarily related to its protein-binding capacitycapacity• Duration is unrelated to the local anesthetic’s half-lifeDuration is unrelated to the local anesthetic’s half-life
Lipid solubility determines the potency of a local Lipid solubility determines the potency of a local anesthetic agentanesthetic agent
cont’d…cont’d…
7373Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Choice of Local AnestheticChoice of Local Anesthetic
Haveles (pp. 123, 125) (Table 9-7)Haveles (pp. 123, 125) (Table 9-7) The vasodilating property can affect both the The vasodilating property can affect both the
potency and duration of actionpotency and duration of action The dental practitioner should become familiar The dental practitioner should become familiar
with a short-, an intermediate-, and a long-acting with a short-, an intermediate-, and a long-acting agentagent
The duration of the procedure and any patient-The duration of the procedure and any patient-specific information will determine the anesthetic specific information will determine the anesthetic of choiceof choice
7474Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (p. 123) (Table 9-8)Haveles (p. 123) (Table 9-8) Benzocaine, an ester, is the most commonly Benzocaine, an ester, is the most commonly
used topical anestheticused topical anesthetic Lidocaine, an amide, is the second most commonly Lidocaine, an amide, is the second most commonly
used used Comparison should take into account their onset, Comparison should take into account their onset,
duration of action, and allergenic potentialduration of action, and allergenic potential The patient should be instructed to avoid eating for 1 The patient should be instructed to avoid eating for 1
hour after application to oral mucosa so that the gag hour after application to oral mucosa so that the gag reflex can become fully functionalreflex can become fully functional
cont’d…cont’d…
7575Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (pp. 123-124)Haveles (pp. 123-124) Amides: lidocaineAmides: lidocaine
Lidocaine is available as the base or hydrochloride Lidocaine is available as the base or hydrochloride saltsalt• The base is preferred when large areas of the mucosal The base is preferred when large areas of the mucosal
surface are ulcerated, abraded, denuded, or erythematoussurface are ulcerated, abraded, denuded, or erythematous Base is available as a jelly and an oral topical solutionBase is available as a jelly and an oral topical solution
• The hydrochloride salt is water soluble and penetrates the The hydrochloride salt is water soluble and penetrates the tissue bettertissue better
Hydrochloride is available as an ointment, an oral topical, and Hydrochloride is available as an ointment, an oral topical, and an oral aerosolan oral aerosol
cont’d…cont’d…
7676Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (p. 124)Haveles (p. 124) Amides: lidocaine and prilocaine (injection-free local Amides: lidocaine and prilocaine (injection-free local
anesthesia)anesthesia) The combination of lidocaine and prilocaine gel (Oraqix) The combination of lidocaine and prilocaine gel (Oraqix)
applied into the periodontal pocket offers pain relief during applied into the periodontal pocket offers pain relief during scaling and root planing proceduresscaling and root planing procedures
Lidocaine provides rapid anesthesia, and prilocaine has a Lidocaine provides rapid anesthesia, and prilocaine has a slower onset of actionslower onset of action
The more common side effects include pain, soreness, The more common side effects include pain, soreness, irritation, edema or redness at the area of application, and irritation, edema or redness at the area of application, and taste changestaste changes
cont’d…cont’d…
7777Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (p. 124)Haveles (p. 124) Esters: benzocaineEsters: benzocaine
Benzocaine, an ester of PABA, cannot be Benzocaine, an ester of PABA, cannot be converted to a water-soluble form for injectionconverted to a water-soluble form for injection
Poorly absorbed and lacks significant systemic Poorly absorbed and lacks significant systemic toxicitytoxicity
Benzocaine is used in many dental offices, Benzocaine is used in many dental offices, although a hypersensitivity reaction is possiblealthough a hypersensitivity reaction is possible
cont’d…cont’d…
7878Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (pp. 124-125)Haveles (pp. 124-125) Esters: cocaineEsters: cocaine
Cocaine is a naturally occurring ester of benzoic Cocaine is a naturally occurring ester of benzoic acid that is potent and extremely toxicacid that is potent and extremely toxic
Although cocaine has ideal pharmacokinetics, the Although cocaine has ideal pharmacokinetics, the systemic absorption and subsequent CNS systemic absorption and subsequent CNS stimulation and its great potential for abuse make stimulation and its great potential for abuse make the use of cocaine as a local anesthetic untenablethe use of cocaine as a local anesthetic untenable
cont’d…cont’d…
7979Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Topical AnestheticsTopical Anesthetics
Haveles (p. 125) (Box 9-7)Haveles (p. 125) (Box 9-7) Precautions in topical anestheticsPrecautions in topical anesthetics
Some local anesthetics are absorbed rapidly when Some local anesthetics are absorbed rapidly when applied topically to mucous membranesapplied topically to mucous membranes
To avoid toxic reactions from surface anesthesia, To avoid toxic reactions from surface anesthesia, the dental health care provider should consider the dental health care provider should consider many factorsmany factors
8080Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Doses of Local Anesthetic and Doses of Local Anesthetic and VasoconstrictorVasoconstrictor
Haveles (pp. 125-126)Haveles (pp. 125-126) The amounts of local anesthetic and The amounts of local anesthetic and
vasoconstrictor contained in a certain volume of vasoconstrictor contained in a certain volume of solution can be calculated from the solution can be calculated from the concentration of that solutionconcentration of that solution The dental health care provider should be able to The dental health care provider should be able to
determine the number of milligrams of both local determine the number of milligrams of both local anesthetic and vasoconstrictor given in any clinical anesthetic and vasoconstrictor given in any clinical situationsituation
The maximal safe dose for each component should The maximal safe dose for each component should not be exceedednot be exceeded
cont’d…cont’d…
8181Copyright © 2011, 2007 Mosby, Inc., an affiliate of Elsevier. All rights reserved.
Doses of Local Anesthetic and Doses of Local Anesthetic and VasoconstrictorVasoconstrictor
Haveles (p. 126)Haveles (p. 126) Each dose should be recorded in the patient’s Each dose should be recorded in the patient’s
chart as soon as possible after the injectionchart as soon as possible after the injection Information recorded should include the strength Information recorded should include the strength
of both ingredients and the volume of solution of both ingredients and the volume of solution used or the number of milligrams of each givenused or the number of milligrams of each given