Transcript topical_anesthetics.ppt

Topical Anesthetics
Topical Anesthetics
Can not penetrate intact skin
More effective if not water soluble
Higher concentrations than injectables
Can cause toxicity
Topical Anesthetics
Concentrations are higher to facilitate
diffusion; leads to a greater potential for
toxicity
Many injectables are not used as topical
because their effective concentrations would
be toxic
Topical Anesthetics
Only penetrate 2-3 mm, on mucous
membranes or disrupted skin
Smallest effective quantities, since rapidly
absorbed into systemic circulation
Cocaine Hydrochloride
Water soluble ester, 2-4% for topical use
Vasoconstrictive, potentiates adrenalin which
may result in dysrythmias
Onset - 1min; duration - up to 2 hrs
Schedule II drug, not recommended for use in
dentistry
Benzocaine
Ester, poorly soluble in water
Available as spray, gel, ointment - 14-20%
Poor CV absorption, little risk of toxicity
Remains at site, increased duration
Possible localized allergic reactions
Can inhibit sulfonamides
Lidocaine Hydrochloride
Amide, 2% solution
Water soluble
Better penetration, greater toxicity than base
Low incidence of allergic reaction
Lidocaine Base
Poor water solubility
5% liquid, ointment, gel
Poor penetration, best on ulcerated, lacerated,
or abraded tissue
Low incidence of allergic reaction
Dyclonine Hydrochloride
Ketone, no cross-sensitization
Slight water solubility, low toxicity
Slow onset -to 10 mins; long duration -to 1 hr
0.5% solution
Butacaine Sulfate
Topical for eyes, ears, nose, throat
Substitute for Cocaine
2X as potent, 2X as toxic
4% dental ointment
Tetracaine Hydrochloride
Ester, highly soluble in water
Potency - 5-8X Cocaine, great potential for
systemic toxicity
2% liquid
Short Duration-5-40mins
Without vasoconstrictors
Lidocaine 2%
Prilocaine 4%
Mepivacaine 3%
Intermediate Duration-45-90mins
With vasoconstrictors
Lidocaine 2% with epi
Mepivacaine 2% with epi or levonordefrin
Prilocaine 4% with epi
Long Duration->90mins
With vasoconstrictors
Bupivacaine 0.5% with epi
Etidocaine 1.5% with epi
Maximum Dosage
Calculated by body weight (mg/kg or lb)
Arbitrary maximum usually approximately at
average adult weight of 70 kg
Decrease in very young, elderly, debilitated,
or medically compromised
Contraindications - Absolute
Med problem Avoid
May use
Anesthetic
same class different class
allergy
Bisulfite
vasoconstrict. non-constrict.
allergy
anesthetics
types
Sulfur
Articaine
non-sulfur
allergy
types
Contraindications - Relative
Med problem Avoid
Atypical
esters
cholinesterase
MethemoPrilocaine,
globinemia
Articaine
Liver disease amides
(severe)
May use
amides
others
esters, or amides
judiciously
Contraindications - Relative
(cont.)
Med problems
Avoid
Kidney disease amides &
(severe)
esters
CV disease
excess
(severe)
vasoconstrictor
Hyperthyroid
excess
(severe)
vasoconstrictor
May use
either
judiciously
plain or
decrease amt
plain or
decrease amt
Selection of an Anesthetic
Duration required for treatment
Posttreatment discomfort
Possibility for self-inflicted injury
Need for hemostasis
Patient’s medical status
Two or more anesthetics ?
Maximum total dose
The total allowable dose for both local
anesthetics should not exceed the lower of
the two maximum doses for the individual
agents.