Transcript Local Anaesthetic Agents In Clinical Use

Local Anaesthetic Agents
In Clinical Use
Dr. Omar Karadsheh
1/11/2015
Outline
• Background
• Selection Of A Local Anaesthetic agent
• Maximum doses of local anaesthetic agents
• Most common local anaesthetic agents used in dentistry
• Topical Anaesthetic agents
Background
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In 1980, five local anaesthetics were available in dental cartridge form in the United States:
lidocaine, mepivacaine, prilocaine, and the combination of procaine and propoxycaine.
Long acting agents bupivacaine (1982 Canada, 1983 United States) and etidocaine (1985).
In 1975, articaine became available in Germany, and later throughout Europe. Articaine
came to North America in 1983 (Canada) and to the United States in 2000.
The combination of procaine and propoxycaine was withdrawn from the U.S. market in
January 1996
rationale for selection of an appropriate local aenesthetic for a given patient at a given
appointment taking into account relative and absolute C/I
Selection of Local Anaesthetic agents
• The duration of pulpal (hard tissue) and soft tissue (total) anaesthesia
needed
• Need for Postoperative pain management
• Need for Haemostasis
• Absolute and relative C/I
Approximate Duration of Action of Local
Anaesthetics
Short Duration (Pulpal Anesthesia Approximately 30 Minutes)
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Mepivacaine HCl 3%
Prilocaine HCl 4% (by infiltration)
 Intermediate Duration (Pulpal Anesthesia Approximately 60 Minutes)
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Articaine HCl 4% + epinephrine 1:100,000
Articaine HCl 4% + epinephrine 1:200,000
Lidocaine HCl 2% + epinephrine 1:50,000
Lidocaine HCl 2% + epinephrine 1:100,000
Mepivacaine HCl 2% + levonordefrin 1:20,000
Prilocaine HCl 4% (via nerve block only)
Prilocaine HCl 4% + epinephrine 1:200,000
Long Duration (Pulpal Anesthesia Approximately 90+ Minutes)
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Bupivacaine HCl 0.5% + epinephrine 1:200,000 (by nerve block)
Duration and Depth of Anaesthesia
Individual response to the drug (the “bell-shaped” curve)
Accuracy in deposition of the local anaesthetic
Status of tissues at the site of drug deposition (vascularity, pH)
Anatomic variation
 Type of injection administered (supraperiosteal [“infiltration”] or nerve
block)
Normal distribution curve (bell-shaped curve):
• Variation in individual response to a drug is common and expected and is
depicted in the so-called bell or normal distribution.
Normal distribution curve (bell-shaped curve):
• Most patients will respond in a predictable manner to a drug's actions (e.g.,
40 to 60 minutes). However, some patients (with none of the other factors
that influence drug action obviously present) will have a shorter or longer
duration of anesthesia. This is to be expected and is entirely normal.
Accuracy in administration
• Although not as significant in certain techniques (e.g., supraperiosteal) or
with certain drugs (e.g., articaine),
• Accuracy in deposition is a major factor in many nerve blocks in which a
considerable thickness of soft tissue must be penetrated to access the nerve
being blocked.
• Deposition of local anaesthetic close to the nerve provides greater depth
and duration of anaesthesia compared with an anaesthetic deposited at a
greater distance from the nerve to be blocked.
The status of the tissues into which a local
anesthetic is deposited
• Inflammation, infection, or pain (acute or chronic) usually decreases depth
and anticipated duration of anaesthesia.
• Increased vascularity more rapid absorptiondecreased duration of
anesthesia.
• Buffered local anaesthetics
• The Gow-Gates mandibular nerve block
Vs.
IANB
Anatomic variation
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Mandible
 height of the mandibular foramen,
 width of the ramus,
 thickness of the cortical plate of bone
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Maxilla
 the zygomatic arch
 Palatal roots
Type of Injection Administered
• Blocks Vs. Infiltration
• Less than recommended volumes decrease the duration of action. Larger
than recommended doses do not provide increased duration.
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For example,
infiltration injection with plain prilocaine 4% 10-15 min pulpal anaesthesia
nerve block with plain Prilociaine 4% 40- to 60-minute pulpal anaesthesia
Maximum doses of L.A
• Unlikely to be reached.
• Milligrams per kilogram (mg/kg) or as milligrams per pound (mg/lb).
• Only estimated values (Bell-shaped curve):
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Normal responders
Hypo-responders
Hyper-responders
• Always minimize drug doses and use the smallest clinically effective dose
Maximum doses of L.A agents
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Two groups of patients represent potentially increased risk from overly high local anaesthetic
blood levels:
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the smaller, lighter-weight (and well-behaved) child,
the debilitated elderly individual.
Medically compromised (Blood, liver and kidney problems)
The calculated drug dose (based on body weight) should be decreased in all “at risk” individuals.
It is suggested that the doctor evaluate each patient's dental care needs and then devise a
treatment plan that takes into account that person's requirement for smaller doses of local
anaesthetic at every treatment appointment.
Overdose (OD)
• When the MRD is exceeded, there is no guarantee that an OD will occur,
only that there is a greater likelihood of its occurrence.
• An OD may be seen with dosages below the calculated MRD (hyperresponders to the drug).
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Another factor in determining whether an OD will occur is the time over
which the local anaesthetic dose was administered.
Calculation of Maximum dosage and Number
of Cartridges (single drug)
Patient: 22 years old, Healthy, Female, 50 kg
L.A: Lidocaine HCL + Epinephrine 1:100,000
MRD Lidocaine: 7 mg/kg
Lidocaine 2%  x 10 = 20 mg/ml
Cartridge contains 1.8 ml solution ,so  20 x 1.8 = 36mg/cartridge
Maximum dose for this patient is: 7 mg/kg x 50 = 350 mg
Number of cartridges= 350/36 = ~10
Local Anaesthetic Agents Used in Dental
Injections
• Ester Type
Procaine
Propoxycaine HCl
Mixture of Procaine + Propoxycaine
• Amide Type
Mepivacaine
Prilocaine
Lidocaine
Articaine
Bupivacaine
Procaine HCL
Procaine HCL
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Until 1996, procaine was found in dental cartridges in combination with a second ester
anesthetic, propoxycaine.
2% procaine (plain) provides essentially no pulpal anaesthesia and from 15 to 30 minutes of
soft tissue anaesthesia.
Procaine produces the greatest vasodilation of all clinically used local anaesthetics.
Procaine is of importance in the immediate management of inadvertent intra-arterial (IA)
injection of a drug; its vasodilating properties are used to aid in breaking arteriospasm.
Although not extremely common, Allergy to esters > amides
Procaine does not exhibit increased toxicity in patients with hepatic dysfunction.
Procaine has a slow clinical onset of anesthesia (6 to 10 minutes) (pKa of 9.1 )—a reason for
inclusion of propoxycaine in the anesthetic cartridge.
Propoxycaine
Mixture
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Propoxycaine was combined with procaine in solution to provide more rapid onset and a
more profound and longer-lasting anesthesia than could be obtained with procaine alone
. Propoxycaine was not available alone because its higher toxicity (seven to eight times that
of procaine) limited its usefulness as a sole agent.
0.4% propoxycaine/2% procaine with 1:20,000 levonordefrin (United States) or with
1:30,000 norepinephrine (Canada) provided approximately 40 minutes of pulpal anesthesia
and 2 to 3 hours of soft tissue anaesthesia.
The use of norepinephrine in local anesthetic solutions is no longer recommended,
especially in areas where prolonged ischemia can lead to tissue necrosis. In the oral cavity,
this is most likely to be seen in the palate.
Amide-Type Local Anesthetics
Lidocaine HCL
Lidocaine HCL
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Lidocaine had replaced procaine (Novocaine) as the most widely used local anaesthetic in
both medicine and dentistry.
Compared with procaine, lidocaine possesses :
 a significantly more rapid onset of action (3 to 5 minutes vs. 6 to 10 minutes),
 produces more profound anaesthesia,
 has a longer duration of action,
 and has greater potency.
Allergy to amide local anaesthetics is virtually non-existent; true, documented, and
reproducible allergic reactions are extremely rare,
Lidocaine Preparations
Lidocaine 2% + Epinephrine
• Decreased bleeding caused by the α-stimulating actions of epinephrine.
• The local anaesthetic is absorbed into the cardiovascular system more
slowly leading to an increase in both depth and duration of anaesthesia:
• approximately 60 minutes of pulpal anaesthesia and 3 to 5 hours of soft
tissue anaesthesia.
Two Percent Lidocaine With Epinephrine
1:50,000
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1:50,000 epinephrine concentration is equal to 20 µg/mL,
Cartridge has 1.8 ml  36 µg per cartridge.
For patients weighing more than 45 kg (100 lb),the maximum epinephrine dose of 200
µg for the healthy patient.
The MRD for epinephrine-sensitive individuals (e.g., certain cardiovascularly
compromised {ASA} 3], and clinically hyperthyroid patients [ASA 3]) is 40 µg per
appointment. This is equivalent to about one cartridge of 1:50,000 epinephrine
The only recommended use of 2% lidocaine with a 1:50,000 epinephrine
concentration is for haemostasis (a situation wherein only small volumes are
infiltrated directly into the surgical site).
Two Percent Lidocaine With Epinephrine
1:100,000
• Administration of 2% lidocaine with epinephrine 1:100,000 decreases blood
flow into the area of injection  less bleeding and longer duration of action
• The epinephrine dilution is 10 µg/mL, or 18 µg per cartridge.
• Epinephrine-sensitive patients should be limited to two cartridges of
1:100,000 epinephrine per appointment.
Which Lidocaine preparation?
• In terms of duration and depth of anaesthesia for most procedures in a
typical dental patient, 2% lidocaine with 1:100,000 epinephrine is preferred
to 2% lidocaine with 1:50,000 epinephrine
• 2% lidocaine with 1:200,000 or 1:300,000 epinephrine provides the same
duration of pulpal and soft tissue anaesthesia, although not the same level
of haemostasis, their use is recommended in elderly patients or hyperresponders to epinephrine
Concluding Notes
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The 1:50,000 solution provides excellent haemostatic action. The 1:100,000 dilution also
may be used for hemostasis, but it is not as effective.
Rebound vasodilation occurs with both 1:50,000 and 1:100,000 epinephrine
concentrations as the tissue concentration of epinephrine decreases.
Minimum volumes of solution should be administered to provide excellent haemostasis.
Signs and symptoms of lidocaine toxicity (overdose) may be the same (central nervous
system [CNS] stimulation followed by CNS depression) as other agents.
However, the stimulatory phase may be brief or may not develop at all. Although muscle
tremor and seizures commonly occur with overly high lidocaine blood levels, the first
signs and symptoms of lidocaine overdose may include drowsiness, leading to loss of
consciousness and respiratory arrest.
Mepivacaine HCl
Mepivacaine HCl
Three Percent Mepivacaine Without a
Vasoconstrictor
• For patients in whom a vasoconstrictor is not indicated
• For dental procedures requiring neither lengthy nor profound pulpal
anaesthesia.
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Mepivacaine plain is the most used local anaesthetic in paediatric patients
when the treating doctor is not a paediatric dentist (e.g., is a general
practitioner) and often is quite appropriate in the management of geriatric
patients.
Two Percent Mepivacaine With a
Vasoconstrictor, Levonordefrin 1:20,000
• Depth and duration of anaesthesia is similar to Lidocaine combinations.
• Mepivacaine is available in combination with levonordefrin (1:20,000).
Where hemostasis is desired, epinephrine is preferred to levonordefrin
• Signs and symptoms of mepivacaine overdose usually follow the more
typical pattern of CNS stimulation followed by depression.
Prilocain HCL
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Potency:2 (procaine = 1; lidocaine = 2).
Toxicity: 1 (procaine = 1; lidocaine = 2); 40% less toxic than lidocaine.
Vasodilating Properties: Prilocaine is a vasodilator. It produces greater vasodilation
than is produced by mepivacaine but less than lidocaine
pKa 7.9.
Onset of Action : Slightly slower than that of lidocaine (3 to 5 minutes).
Effective Dental Concentration 4%.
Anaesthetic Half-Life: 1.6 hours.
Topical Anaesthetic Action:
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Not in clinically acceptable concentrations.
Prilocaine, in its uncharged base form, is an integral part of EMLA cream
Prilocaine HCL
Metabolism:
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Is significantly different from lidocaine and mepivacaine,it undergoes more rapid and complete
biotransformation
Orthotoluidine, a by-product, can induce the formation of methemoglobin, producing
methemoglobinemia if large doses are administered reducing the blood's oxygen-carrying capacity,
at times sufficiently to cause observable cyanosis.
Limiting the total prilocaine dose to 600 mg (FDA recommendation) avoids symptomatic cyanosis.
Excretion:
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Prilocaine and its metabolites are excreted primarily via the kidneys. Renal clearance of prilocaine is
faster than for other amides, resulting in its faster removal from the circulation.
Pregnancy Classification B.
Safety During Lactation : Unknown.
Prilocaine Preparations
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Infiltration with Prilocaine 4% plain provides short durations of pulpal (10 to 15
minutes) and soft tissue ( to 2 hours) anesthesia,
whereas regional nerve block provides pulpal anesthesia for up to 60 minutes
(commonly 40 to 60 minutes) and soft tissue anesthesia for 2 to 4 hours. Thus
prilocaine plain frequently is able to provide anaesthesia that is equal in duration to
that attained with lidocaine or mepivacaine with a vasoconstrictor.
Prilocaine with epinephrine provides lengthy anaesthesia while offering a less
concentrated epinephrine dilution: 1:200,000.
In epinephrine-sensitive patients requiring prolonged pulpal anesthesia (≥60
minutes), prilocaine plain or with 1:200,000 epinephrine is strongly recommended. It
is rapidly biotransformed and, for this reason, is considered to be a safe local
anaesthetic (e.g., lower toxicity)
C/I of Prilocaine
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Prilocaine is relatively contraindicated in patients with idiopathic or congenital
methemoglobinemia, hemoglobinopathies (sickle cell anemia), anemia, or cardiac or
respiratory failure evidenced by hypoxia, because methemoglobin levels are increased,
decreasing oxygen-carrying capacity.
Prilocaine administration is also relatively contraindicated in patients receiving
acetaminophen or phenacetin, both of which produce elevations in methemoglobin levels.
Neurotoxicity and paresthesia ?
Articaine HCl
• Classification : Hybrid molecule. Classified as an amide; however, it possesses
both amide and ester characteristics.
• Potency 1.5 times that of lidocaine; 1.9 times that of procaine.
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Toxicity Similar to lidocaine and procaine.
Articaine HCL
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Metabolism : Articaine is the only amide-type local anesthetic that contains a
thiophene group. Because articaine HCl is the only widely used amide-type local
anesthetic that contains an ester group, biotransformation of articaine HCl occurs in
both plasma (hydrolysis by plasma esterase) and liver (hepatic microsomal enzymes).
Excretion: Via the kidneys; approximately 5% to 10% unchanged, approximately
90% metabolites.
Vasodilating Properties: Articaine has a vasodilating effect equal to that of lidocaine.
Procaine is slightly more vasoactive.
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Onset of Action:
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Articaine 1:200,000, infiltration 1 to 2 minutes, mandibular block 2 to 3 minutes;
Articaine 1:100,000, infiltration 1 to 2 minutes, mandibular block 2 to 3 minutes.
Effective Dental Concentration: 4% with 1:100,000 or 1:200,000 epinephrine.
Anaesthetic Half-Life: 0.5 hours [27 minutes].
Topical Anaesthetic Action: Not in clinically acceptable concentrations.
Pregnancy Classification: C.
Safety During Lactation: Unknown (use with caution in females who are breastfeeding because it is not known whether articaine is excreted in milk).
Maximum Recommended Dose: The FDA maximum recommended dose is 7.0 mg/kg
or 3.2 mg/lb of body weight for the adult patient
Articaine HCL
• Articaine, as the newest local anaesthetic drug marketed
• It has been claimed that articaine is able to diffuse through soft and hard
tissues more reliably than other local anesthetics
• Clinically, it is claimed that following maxillary buccal infiltration, articaine on
occasion may provide palatal soft tissue anesthesia, obviating the need for
palatal injection
• The significant success of articaine administered by buccal infiltration in the
mandible of adult patients.
• Reports of paraesthesia following local anaesthetic administration. An
overwhelming majority of reported cases occurred following inferior alveolar
nerve block and primarily involved the lingual nerve
Articaine HCL relative C/I
• Articaine HCl should be used with caution in persons with hepatic disease
and significant impairment in cardiovascular function
• Class C drug during pregnancy.
• Use with caution in females who are breast-feeding
• Administration to children younger than 4 years is not recommended
because insufficient data are available to support such usage.
Bupivacaine HCl
Bupivacaine HCL
Bupivacaine HCL
• MRD bupivacaine is 90 mg.
• Bupivacaine is available as a 0.5% solution with 1:200,000 epinephrine
• Two primary indications for its utilization in dentistry:
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Lengthy dental procedures for which pulpal (deep) anesthesia in excess of 90
minutes is necessary (e.g., full mouth reconstruction, implant surgery, extensive
periodontal procedures)
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Management of postoperative pain (e.g., endodontic, periodontal, postimplant,
surgical) The patient's requirement for postoperative opioid analgesics is
considerably lessened.
Relative C/I
• Bupivacaine is not recommended in younger patients or in those for whom
the risk of postoperative soft tissue injury produced by self-mutilation is
increased, such as physically and mentally disabled persons.
• Bupivacaine is rarely indicated in children because pediatric dental
procedures are usually of short duration.
Anesthetics For Topical Application
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Conventional topical anesthetics are unable to penetrate intact skin but do diffuse through
abraded skin (e.g., sunburn) and any mucous membranes.
The concentration of a local anaesthetic applied topically is typically greater than that of the
same local anaesthetic administered by injection.
The higher concentration facilitates diffusion of the drug through the mucous membrane.
Higher concentration also increases the risk of toxicity, both locally to tissues and systemically
if the drug is efficiently absorbed.
Do not contain vasoconstrictors and local anesthetics have vasodilatory properties.
• Many local anesthetics used effectively via injection prove ineffective when
applied topically (e.g., articaine HCl, mepivacaine HCl, prilocaine HCl,
procaine HCl) because the concentrations necessary to produce anesthesia
via topical application are high, with significantly increased overdose and
local tissue toxicity potential .
• As a general rule, topical anesthetics are effective only on surface tissues (2
to 3 mm). Tissues deep to the area of application are poorly anesthetized, if
at all. However, surface anesthesia does allow for atraumatic needle
penetration of the mucous membrane
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The topical anesthetics benzocaine and lidocaine base (not the HCl form used by injection)
are insoluble in water. However, they are soluble in alcohol, propylene glycol, polyethylene
glycol, and other vehicles suitable for surface application. The base forms of benzocaine
and lidocaine are slowly absorbed into the cardiovascular system and therefore are less
likely to produce an overdose reaction following typical dental application.
Some topical anesthetics are marketed in pressurized spray containers. Although they are
no more effective than other forms, it is difficult to control the amount of anaesthetic
expelled and to confine it to the desired site of application. Spray devices that do not
deliver measured doses should not be used intraorally.
Topical Anaesthesia
Benzocaine
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Benzocaine (ethyl p-aminobenzoate) is an ester
Poor solubility in water
Poor absorption into the cardiovascular system
Systemic toxic (overdose) reactions virtually
unknown
Remains at the site of application longer,
providing a prolonged duration of action
Not suitable for injection
Inhibits the antibacterial action of sulfonamides
Availability (Benzocaine is available in the
following formulations in numerous dosages:
aerosol, gel, gel patch, ointment, and solution.)
Topical Agents
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Cocaine hydrochloride is an ester that occurs naturally as a white crystalline solid
that is highly soluble in water:
Used exclusively via topical application.
Injection of cocaine is contraindicated because its highly toxic
Onset of topical anesthetic action is quite rapid, usually occurring within 1 minute.
Duration of anesthetic action may be as long as 2 hours.
It is absorbed rapidly but eliminated slowly (elimination half-life = 42 minutes). .
Cocaine
• Cocaine is the only local anaesthetic consistently demonstrated to produce
vasoconstriction
• Potentiate the actions of endogenous epinephrine and norepinephrine.
• Addition of vasoconstrictors to cocaine therefore is unnecessary and is
potentially dangerous, increasing the likelihood of dysrhythmias, including
ventricular fibrillation
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Classified as a Schedule II drug under the Controlled Substances Act. Repeated use
results in psychological dependence and tolerance.
Overdose of cocaine is not uncommon following illicit use, primarily because the drug
is readily absorbed from the nasal mucosa and its dosage is not carefully monitored.
Clinical manifestations of mild overdose include euphoria, excitement, restlessness,
tremor, hypertension, tachycardia, and tachypnea.
Clinical manifestations of acute cocaine overdose include excitement, restlessness,
confusion, tremor, hypertension, tachycardia, tachypnea, nausea and vomiting,
abdominal pain, exophthalmos, and mydriasis; these are followed by depression (CNS,
cardiovascular, respiratory) and death from respiratory arrest.
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It is recommended that the concentration of cocaine not exceed 4% for topical
application to oral mucous membranes.
Solutions of cocaine are unstable and deteriorate on standing.
Because of the extreme abuse potential of cocaine, its use as a topical anesthetic in
dentistry is not recommended.
Topically applied cocaine is used occasionally before nasal-endotracheal intubation
is performed in the operating theater to minimize bleeding from this highly
vascular region and pain as the endotracheal tube is passed.
Dyclonine Hydrochloride
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Dyclonine hydrochloride) is a ketone derivative without an ester or amide linkage that may be used in patients who are allergic to
the common anesthetics.
Dyclonine offers advantages over other topical anesthetic agents
it to be effective and safe.
Cross-sensitization with other local anesthetics does not occur
Slightly soluble in water
Potency equal to that of cocaine
Onset of anesthesia slow, requiring up to 10 minutes
Duration of anesthesia may be as long as 1 hour.
Systemic toxicity is extremely low, primarily because of the agent's poor water solubility.
Not indicated for use by injection; irritating to tissues at the site of application 8 A 0.5% solution is used in dentistry. Maximum
recommended dose is 200 mg (40 mL of a 0.5% solution). 9 Dyclonine was available as Dyclone in a 0.5% solution: each 100 mL of
solution contained 500 mg of dyclonine HCl, 300 mg of chlorobutanol as a preservative, sodium chloride for isotonicity, and
hydrochloric acid, as needed, to adjust pH. The Dyclone brand was withdrawn from the North American market in 2001.
EMLA (Eutectic Mixture of Local Anesthetics)
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EMLA cream (composed of lidocaine 2.5% and prilocaine 2.5%) is an emulsion in which the oil
phase is a eutectic mixture of lidocaine and prilocaine in a ratio of 1:1 by weight.
provide surface anesthesia for intact skin (other topical anesthetics do not produce anesthesia
on intact skin, only abraded skin
Used primarily before painful procedures such as venipuncture and other needle insertions
EMLA has gained popularity among needle-phobic adults and persons having other superficial,
but painful, procedures performed (e.g., hair removal
Because intact skin is a barrier to drug diffusion, EMLA must be applied 1 hour before the
procedure. Satisfactory numbing of the skin occurs 1 hour after application, reaches a maximum
at 2 to 3 hours, and lasts for 1 to 2 hours after removal.
EMLA is supplied in a 5-g or 30-g tube or as an EMLA anesthetic disc
EMLA
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EMLA is contraindicated for use in patients with congenital or idiopathic methemoglobinemia,
infants younger than 12 months who are receiving treatment with methemoglobin-inducing
agents, and patients with known sensitivity to amide-type local anesthetics or any other
component of the product.
“EMLA is not recommended for use on mucous membranes,” subsequent clinical trials have
demonstrated satisfactory results.
Bernardi and associates demonstrated statistically significant analgesia in 52 dental patients
requiring removal of metal maxillary or mandibular splints used to contain fractures. A study
showed that use of EMLA could eliminate to some extent use of the needle in procedures
performed in pediatric dentistry.
Lidocaine
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Lidocaine is available in two forms for topical application:
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lidocaine base, which is poorly soluble in water, is used as a 5% concentration, and is indicated for use on
ulcerated, abraded, or lacerated tissue;
 and lidocaine hydrochloride, its water-soluble preparation, which is used as a 2% concentration. The water-
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soluble form of lidocaine penetrates tissue more efficiently than the base form. However, systemic
absorption is also greater, providing greater risk of toxicity than the base form.
Maximum recommended dose following topical application is 200 mg.
Availability: Lidocaine base is available as an aerosol spray, ointment, patch, and solution in
various dosage forms
Lidocaine HCl is available as an oral topical solution in 20 mg/mL (viscous) and 40 mg/mL
(solution).
Tetracaine Hydrochloride
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Tetracaine hydrochloride) is a long-duration ester local anaesthetic that can be injected or applied
topically, Highly soluble in water , Applied topically,
five to eight times more potent than cocaine
Onset of action after topical application is slow.
Duration of action is approximately 45 minutes after topical application.
Metabolized in plasma and the liver by plasma pseudocholinesterase at a slower rate than procaine
Rapidly absorbed through mucous membranes. Use should be limited to small areas to avoid rapid
absorption. Other, more slowly or poorly absorbed agents should be used in lieu of tetracaine when
larger areas of topical anesthesia are necessary
Maximum recommended dose of 20 mg when used for topical application. This represents 1 mL of a
2% solution.
Caution is urged because of great potential for systemic toxicity.
• Availability (Canada): a Aerosol: 0.7 mg/metered spray 1 Supracaine
• Tetracaine in a 3% concentration, with the vasoconstrictor oxymetazocine,
has been shown to provide pulpal anesthesia of maxillary teeth when
administered by aerosol spray into a patient's nares.
Summary
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Amides are preferred to esters whenever possible:
A minimum of two drugs is recommended for most offices:
1 Short-duration pulpal anaesthetic (≈30 minutes)
2 Intermediate-duration pulpal anaesthetic (≈60 minutes)
3 Long-duration pulpal anaesthetic (90 or more minutes)
4 Topical anaesthetic for tissue preparation before injection of local anaesthetic
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