local anesthetic.ppt

LOCAL ANESTHETICS MEDICINES

1. LOCALANESTHESIA
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2. TERMINOLOGIES
•Analgesia-lossofpainsensationunaccompaniedbylossofotherformsof
sensibility.
•Anesthesia-lossofallformsofsensationincludingpain,touch,temperature
andpressureperceptionandmaybeaccompaniedbylossofmotorfunction.
•Generalanesthesia-reversiblelossofallsensationandconsciousness.
•Localanesthesia–Lossofsensationinacircumscribedareaofthebody
causedbyadepressionofexcitationinthenerveendingsoraninhibitionofthe
conductionprocessofperipheralnerve.
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3. ADVANTAGES
•Patientawakeandco-operative
•Littledistortionofnormalphysiology-minimalriskto thepatients
•Lowmortality
•Noadditionaltrainedpersonnel
•Techniquesnotdifficulttomaster
•Lowfailurerates
•costeffective
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4. INDICATIONS
•Extractionofteeth
•Alveolplastyandalveolectomy
•Incisionanddrainageofabscesses
•Cavitypreparationespeciallyindeeperpainfulcavities
•Pulpprocedureslikepulpotomyandpulpectomy
•Treatmentoftrismus
•Periodontalsurgeryandgingivalsurgery
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5. CONTRAINDICATIONS
•Fearandapprehension
•Localinfection
•Allergytocomponentsoflocalanaestheticsolution
•Patientbelowageofreasoning
•Unco-operativepatient(eg.mentallychallenged)
•Majororalsurgery
•Anomaliesofnervesupply
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6. CLASSIFICATION
1.Based on the potency and duration of action:
•Injectable
a)Low potency and short duration.
E.g.: procaine and chloroprocaine
b)Intermediate potency and duration E.g.: Lignocaine and
prilocaine
c)High potency and long duration
E.g.: Tetracaine, bupivicaine, Ropivicaine and dibucaine
•Surface anesthetics
a)Soluble
b)Insoluble
E.g.: Cocaine, lignocaine, tetracaine
Eg: Benzocaine, Oxathezine
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7. 2.Based on Chemical
Composition
Benzoic Acid
Esters
Butacaine,
Cocaine,
Benzocaine,
Hexylcaine,
Piperocaine,
Tetracaine
Para
aminobenzoic
acid esters
Procaine
(Novocain)
Propoxycain
e
Chloroprocai
ne
Amide
Bupivacaine ,
Etidocaine,
Lidocaine,
Mepivacaine,
Prilocaine,
Articaine
Quinoline
Centbucridine
Ester
NonEster
group
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8. 3.Basedonbiologicalsiteof
action
•Class A-Agents acting at receptor site on the external surface of the nerve
membrane.
E.g.: Tetrodotoxin
•Class B-receptor site on the internal surface of nerve membrane.
E.g.: Lidocaine
•Class C-receptor independent physiochemical mechanism.
E.g.: Benzocaine
•Class D-combination of receptor and receptor independent mechanism. E.g.:
Atricaine, Lidocaine, mepivicaine
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9. Basicstructureof localanesthetics
Local anesthetic drugs are weak organic bases and are insoluble in water.
They can be converted into soluble salts, usually the hydrochlorides
Local anesthetic molecule consist of :
•Lipophilicpart-Itconstitutesthemajorbulkofmolecule.Itisaromaticin
nature derived from benzene, aciline or thiopene.
•Hydrophilicpart-Itisanaminoderivativeofethylalcoholoraceticacid.
Localanestheticagentslackingthispartaresaidtohavegoodtopical
anestheticaction.E.g.:Benzocaine.
•Intermediatehydrocarbonchain-Itmainlyconsistsofestergrouporan
amidegroupbasedonwhichpropertiesvary.
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10. Desirablepropertiesofanideal localanesthetics
•Non-irritant, Non-AntigenicandNon-allergic
•Anesthesiashouldbecompletelyreversible
•Minimalsystemictoxicity
•EffectivethroughtopicalapplicationandInjection
•HighlyPotent,rapidaction,adequatedurationofanesthesia
•StablesolutionandSterilizable
•Administeredwithotheragents
E.g.:Vasoconstrictorswithoutlossofproperties
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11. Mechanismofaction
•DisplacementofCa ionsfromthenervereceptorsite
•Bindingoflocalanestheticmoleculetothisreceptorsite
•Blockadeofthesodiumchannel
•Decreaseinsodiumconductance
•Depressionofrateofelectricaldepolarization
•Failuretoachievethresholdpotentiallevel
•Lackofdevelopmentofpropagatedactionpotential
•Conductionblockade
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12. LOCALANESTHETICAGENT
Most important constituent.
A) Lidocaine Hydrochloride:
•Chemical Formulae: 2-Diethylamino-2
1,6
1-acetoxylidide hydrochloride
•Metabolism: In liver by microsomal fixed Function oxidases to
monoethyl glycerine & xylidide. Xylidide is a local anesthetic &
potentially toxic.
•Excretion: Excretion is via kidney.
•Onset of action: Rapid, 2 to 3 minutes.
•Ideal dental concentration: 2%
•pH of the plain solution : 6.5
•pH of vasoconstrictor containing solution : 5.5
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13. VASOCONSTRICTOR
These are drugs that constrict blood vessels and thereby control tissue perfusion.
They are added to the local anesthetics solution to counteract the agents vasodilating
actions.
Vasoconstrictors are highly important for the following reasons:
•By vasoconstricting blood vessels, the vasoconstrictors decrease the blood flow to
the
site of injection.
•Absorption of local anesthetic agent into the blood stream is slowed, thereby
producing low level in blood.
•Lower levels of anesthetic decrease the risk of overdose reaction.
•Higher concentration of Local anesthetic agent remains in and around the nerve for
longer period, thereby increasing the duration of action.
•Minimizes the bleeding at the site of administration.
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14. •Mostcommonlyused vasoconstrictor
isadrenaline
•concentrationof1:100,000to
1:200,000
•recommendeddose of adrenalineis
0.3mmg
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15. CONTRAINDICATIONSOF
VASOCONSTRICTORS
Highbloodpressure
Cardiovasculardisease
Hyperthyroidpatients
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16. Reducing
AgentVasoconstrictors in local anesthetic are unstable in the solution form and may
oxidize, especially on prolonged exposure to sun. 0.5 mg/ml of sodium bisulfite is added
as a reducing agent. It competes for the available oxygen in the vial.
Preservative
It is added to maintain the stability of the solution. Methyl paraben 1 mg/ml is
added
to the solution in order to give it an extended shelf life.
Fungicide
Small quantities of thymol is added
Salts
Sodium chloride is added to make the solution isotonic
Vehicle:
Anesthetic agent and other constituents of the vial are dissolved in distilled water
which is used as a vehicle for making the solution
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17. PROCAINEHCl
⚫ Because of its vasodilating properties it
is used in immediate intraarterial injection.
⚫Allergy is more common than amide group
⚫Maximum Recommended dose –1000mg
⚫Onset of Action –6 to 10 min
⚫Half Life –6 min
LocalAnestheticAgents–Ester
Group
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18. PROPOXYCAINE HCL
⚫Propoxycaine was combined with procain in solution to provide
⚫more rapid onset and more profound and long lasting anesthesia
⚫Onset of action = rapid ( 2 to 3 min )
⚫ This combination is recommended when amides are
contraindicated (0.4% propoxycaine/2% procaine )1:30,000
norepinephrine
⚫Provides 40 min of pulpal anesthesia and 2 to 3 hrs of soft tissue
anesthesia
⚫MRD = 6.6 mg/ kg
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19. AMIDESTYPELOCALANESTHESIA
LIDOCAINEHCL
⚫ Lignocain possesses significant more rapid onset of
action(2 to 3 min) produces more profound anesthesia (~90min) long
duration of action and has a great potency.
⚫Allergy is very rare it is its major clinical advantage.
⚫ Most widely used anesthetic represents GOLD
STANDARD drug to which all new LA are compared
⚫2% lidocain HCL with or with out vasoconstrictor
⚫MRD= 7.0mg/kg of body weight
⚫Not to exceed 500mgHalf life: ~90 mins
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20. MEPIVACAINE HCL
⚫Pulpal anesthesia= 20 to 40 min
⚫Onset of action = rapid (1 to 2 min)
⚫Effective dental concentration=3%
⚫Anesthetic half life = 1.9 hrs
⚫MRD= 6.6mg/kg of body weight
⚫ Mild vasodilatation properties provides a longer
duration of anesthesia
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21. ARTICAINEHCl
⚫Potency-1.5timesthatoflidocaine,1.9timesthatofprocaine
⚫Toxicity–similarwithlidocaineandprocaine
⚫Onsetofaction-1–3min.
⚫Anesthetichalflife–0.5hrs.
⚫MRD–7.0mg/kgbd.wt
⚫Articaineisabletodiffusethroughsoftandhardtissuesmorerapidlythan
otherlocalanesthetics.
⚫Paresthesia.
⚫Cautioninhepatic,cvsdiseases.
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22. BUPIVACAINEHCl
⚫Potency–4 timesthatoflidocaine,mepivacaine,andprilocaine..
⚫Toxicity–4timeslessthanthatoflidocaineandmepivacaine.
⚫Vasodialationismorethanthatoflidocaine,mepicaine,andprilocaine.
⚫Onsetofaction–6–10min.
⚫Anesthetichalflife–2.7hrs.
⚫Effectivedentalconc.–0.5%
⚫MRD=1.3mg/kgbody.wt
⚫Nottoexceed90mg
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23. ETHIDOCAINEHCL
⚫Potency–4timesthatoflidocaine.
⚫Toxicity–2timesastoxicaslidocaineaftersubcutaneousadministration.
⚫4 timesastoxicaslidocaineafteri.v.administration.
⚫Onsetofaction–1.5–3min.
⚫Anaesthetichalflife–2.6hrs.
⚫MRD =8.0mg/kgbd.wt
⚫Upto400mg
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24. TOPICALANESTHETICS
⚫
⚫
⚫
⚫
⚫
⚫
Benzocaine –eg : Hurricaine, Super Dent, Topex.
Cocaine HCl-not recommended. Dyclonine
HCL –0.5%
EMLA-lidocaine 2.5% + prilocaine 2.5%.
Lidocaine –Base / HCl eg : Xylocaine, octocaine.
Tetracaine HCl –eg : Supracaine.
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25. LOCALCOMPLICATIONS
•Needlebreakage
•Painoninjection
•Burningoninjection
•Persistentanaesthesiaorparesthesia
•Trismus
•Hematoma
•Sloughingofthetissue/softtissueinjury
•Facialnerveparalysis
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26. SYSTEMIC COMPLICATIONS
•Toxicity
•Allergy
•Anaphylaxis
•Syncope
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27. OVERDOSAGE/TOXICITY
Causes :
Total dosage of LA administered is too large.
Absorption of LA from the site of injection is
rapid. Intravascular administration.
Unusually slow biotransformation. Slow
elimination though the kidney.
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28. CNS
Agitation, talkativeness, irritability. Tonic clonic seizures.
CNS depression, Respiratory arrest.
CVS
Alterations in ECG. Myocardial depression. Decreased
cardiac output. Peripheral vasodialation.
Severe bradycardia → cardiac arrest.
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29. THANKYOU
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