LOCAL ANESTHETICS MEDICINES

1. LOCAL ANESTHESIA
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2. TERMINOLOGIES
•Analgesia - loss of pain sensation unaccompanied by loss of other forms of
sensibility.
•Anesthesia - loss of all forms of sensation including pain, touch, temperature
and pressure perception and may be accompanied by loss of motor function.
•General anesthesia - reversible loss of all sensation and consciousness.
•Local anesthesia – Loss of sensation in a circumscribed area of the body
caused by a depression of excitation in the nerve endings or an inhibition of the
conduction process of peripheral nerve.
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3. ADV
ANTAGES
• Patient awake and co-operative
• Little distortion of normal physiology- minimal risk to the patients
• Low mortality
• No additional trained personnel
• Techniques not difficult to master
• Low failure rates
• cost effective
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4. INDICATIONS
• Extraction of teeth
• Alveolplasty and alveolectomy
• Incision and drainage of abscesses
• Cavity preparation especially in deeper painful cavities
• Pulp procedures like pulpotomy and pulpectomy
• Treatment of trismus
• Periodontal surgery and gingival surgery
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5. CONTRAINDICATIONS
• Fear and apprehension
• Local infection
• Allergy to components of local anaesthetic solution
• Patient below age of reasoning
• Un co-operative patient (eg. mentally challenged)
• Major oral surgery
• Anomalies of nerve supply
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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
Non Ester
group
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8. 3.Based on biological site of
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. Basic structure of local anesthetics
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 :
•Lipophilic part- It constitutes the major bulk of molecule. It is aromatic in
nature derived from benzene, aciline or thiopene.
•Hydrophilic part-It is an amino derivative of ethyl alcohol or acetic acid.
Local anesthetic agents lacking this part are said to have good topical
anesthetic action. E.g.: Benzocaine.
•Intermediate hydrocarbon chain-It mainly consists of ester group or an
amide group based on which properties vary.
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10. Desirable properties of an ideal local anesthetics
• Non-irritant , Non-Antigenic and Non-allergic
• Anesthesia should be completely reversible
• Minimal systemic toxicity
• Effective through topical application and Injection
• Highly Potent ,rapid action, adequate duration of anesthesia
• Stable solution and Sterilizable
• Administered with other agents
E.g.: Vasoconstrictors without loss of properties
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11. Mechanism of action
• Displacement of Ca ions from the nerve receptor site
• Binding of local anesthetic molecule to this receptor site
• Blockade of the sodium channel
• Decrease in sodium conductance
• Depression of rate of electrical depolarization
• Failure to achieve threshold potential level
• Lack of development of propagated action potential
• Conduction blockade
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12. LOCAL ANESTHETIC AGENT
Most important constituent.
A) Lidocaine Hydrochloride:
•Chemical Formulae: 2-Diethylamino-21,61-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. • Most commonly used vasoconstrictor
is adrenaline
• concentration of 1:100,000 to
1:200,000
• recommended dose of adrenaline is
0.3mmg
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15. CONTRAINDICATIONS OF
VASOCONSTRICTORS
High blood pressure
Cardiovascular disease
Hyperthyroid patients
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16. Reducing
Agent
Vasoconstrictors 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. PROCAINE HCl
⚫ 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
Local AnestheticAgents – 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. AMIDES TYPE LOCALANESTHESIA
LIDOCAINE HCL
⚫ 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 500mg Half 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. ARTICAINE HCl
⚫ Potency - 1.5 times that of lidocaine,1.9 times that of procaine
⚫ Toxicity – similar with lidocaine and procaine
⚫ Onset of action - 1 – 3 min.
⚫ Anesthetic half life – 0.5 hrs.
⚫ MRD – 7.0 mg / kg bd.wt
⚫ Articaine is able to diffuse through soft and hard tissues more rapidly than
other local anesthetics.
⚫ Paresthesia.
⚫ Caution in hepatic, cvs diseases.
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22. BUPIVACAINE HCl
⚫ Potency – 4 times that of lidocaine, mepivacaine, and prilocaine..
⚫ Toxicity – 4 times less than that of lidocaine and mepivacaine.
⚫ Vasodialation is more than that of lidocaine, mepicaine, and prilocaine.
⚫ Onset of action – 6 – 10 min.
⚫ Anesthetic half life – 2.7hrs.
⚫ Effective dental conc. – 0.5%
⚫ MRD = 1.3 mg/ kg body.wt
⚫ Not to exceed 90mg
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23. ETHIDOCAINE HCL
⚫ Potency – 4 times that of lidocaine.
⚫ Toxicity – 2 times as toxic as lidocaine after subcutaneous administration.
⚫ 4 times as toxic as lidocaine after i.v. administration.
⚫ Onset of action – 1.5 – 3 min.
⚫ Anaesthetic half life – 2.6 hrs.
⚫ MRD = 8.0 mg / kg bd.wt
⚫ Up to 400mg
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24. TOPICAL ANESTHETICS
⚫
⚫
⚫
⚫
⚫
⚫
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. LOCAL COMPLICATIONS
• Needle breakage
• Pain on injection
• Burning on injection
• Persistent anaesthesia or paresthesia
• Trismus
• Hematoma
• Sloughing of the tissue / soft tissue injury
• Facial nerve paralysis
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26. SYSTEMIC COMPLICATIONS
• Toxicity
• Allergy
• Anaphylaxis
• Syncope
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27. OVER DOSAGE/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. THANK YOU
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