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LOCAL ANESHTHESIA dental, composition.pptx
- 2. Definition Methods of induce local anesthesia Basics of nerve conduction Mechanism of action of local anesthetic Ideal properties of local anesthetic agent Theories of local anesthesia Classification of local anesthetic agents Composition of clinically available local anesthetic solution Characteristics of local anesthetic agent Lignocaine Conclusion
- 3. Local anesthesia has been defined as transient reversible loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings or inhibition of the conduction process in peripheral nerves. An important feature of local anesthesia is that it produces this loss of sensation without inducing loss of consciousness.
- 4. 1. mechanical trauma (compression of tissues) 2. low temperature 3. anoxia 4. chemical irritants 5. neurolytic agents such as alcohol and phenol 6. chemical agents such as local anesthetics Only those methods or substances that induce a transient and completely reversible state of anesthesia have application in clinical practice
- 7. • 70-80 AU thick • Bilipid layer • Hydrophobic and hydrophilic ends • Has protein receptors
- 13. ALTERS RESTING POTENTIAL ALTERS THRESHOLD POTENTIAL DECREASES RATE OF DEPOLARIZATION PROLONGS RATE OF REPOLARIZATION INTERFERES WITH EXCITATION OF NERVE
- 14. Non irritating No permanent damage to nerve Low systemic toxicity Effective regardless mode of application Rapid onset of action Adequate duration of action Sufficient potency Non allergy inducing Stable in solution
- 15. ACETYLCHOLINE THEORY CALCIUM DISPLACEMENT THEORY SURFACE CHARGE (REPULSION) THEORY MEMBRANE EXPANSION THEORY SPECIFIC RECEPTOR THEORY 1 2 3 4 5
- 16. Acetylcholine is involved in nerve conduction in addition to its role as a neurotransmitter at nerve synapses No evidence exists supporting this theory
- 17. States that local anesthetic nerve block is produced by the displacement of calcium from some membrane site that controls permeability to sodium Although varying the concentration of calcium ions bathing a nerve does not affect local anesthetic potency
- 18. Cationic (RNH+) (p. 15) drug molecules aligned at the membrane- water interface make the electrical potential at the membrane surface more positive, thus decreasing the excitability of the nerve Conventional local anesthetics act within membrane channels rather than at the membrane surface. Also, the surface charge theory cannot explain the activity of uncharged anesthetic molecules in blocking nerve impulses(e.g., benzocaine).
- 19. Local anesthetic molecules diffuse to hydrophobic regions of excitable membranes, producing a general disturbance of the bulk membrane structure This results in a decreased diameter of sodium channels, which leads to inhibition of both sodium conductance and neural excitation It serves as a possible explanation for the local anesthetic activity of a drug such as benzocaine, which does not exist in cationic form yet still exhibits potent topical
- 20. Local anesthetics act by binding to specific receptors on the sodium channel. The action of the drug is direct, not mediated by some change in the general properties of the cell membrane. Once the local anesthetic has gained access to the receptors, permeability to sodium ions is decreased or eliminated, and nerve
- 21. BASED ON SOURCE OF OCCURENCE BIOLOGICAL SITE OF ACTION CHEMICAL COMPOSITION DURATION OF ACTION MODE OF APPLICATION
- 23. LIPOPHILIC PART Largest part of molecule Aromatic in structure Derived from: A : Benzoic acid B : Aniline C : Thiopene HYDROPHILIC PART Amino derivative of ethyl alcohol or acetic acid LA without hydrophilic part cannot be injected It is suitable for topical use INTERMEDIATE PART Joins the hydrophilic and hydrophobic part This hydrocarbon linkage can either be amide linkage or ester linkage
- 25. NATURAL LY OCCURIN G SYNTHETI C OTHER DRUGS WITH LOCAL ANESTHETI C ACTIONS COCAINE SAXITOXIN TETRODOXIN CLOVE OIL PHENOL CHLORPROMAZINE DIPHENHYDRAZINE NITROGEN COMPOUND S NON- NITROGEN COMPOUND S
- 26. SYNTHETIC LOCAL ANESTHETIC AGENTS NITROGENOUS DERIVATIVES OF NON NITROGENOUS COMPOUNDS PABA ACETANILID E QUINOLON E ACRIDIN E PROCAINE BENZOCAIN E LIGNOCAIN E CINCHOCAIN E NUPERCAINE BUCRICAINE CENTBUCRIDI NE CENTBLOCK BENZYL ALCOHOL PROPANEDIOL
- 27. SHORT ACTIN G ULTRA SHORT ACTIN G MEDIU M ACTING LONG ACTIN G Less than 30 mins 45-75 mins 90- 150mins 180 min/more PROCAINE CHLORPROCAIN E(without vasoconstrictor) 2% LIDOCAINE 4% PRILOCAINE (with vasoconstrictor) 2% MEPIVACAINE (with vasoconstrictor) 0.5% BUPIVACAINE 0.5-1.5% ETIDOCAINE (with
- 28. Individual response to the drug Accuracy in deposition Status of tissues at the site of drug deposition Anatomic variation Type of injection administered
- 30. LOCAL ANESTHETI C AGENT VASOCONSTRICTOR ANTIOXIDANT PRESERVATIV E FUNGICIDE SALT VEHICLE COMPOSITION 2% lignocaine Methyl paraben Thymol Distilled water NaCl solution Sodium metabisulphit Adrenalin e
- 31. ADVANTAGES: 1. Constrict blood vessels and decrease perfusion to the site of administration of drug 2. Absorption of local anesthetic agent into the CVS is slowed resulting in lower anesthetic blood levels 3. Risk of local anesthetic toxicity is decreased 4. More local anesthetic enters into the nerve thereby increasing the duration of action 5. Vasoconstrictors decrease bleeding at the site of administration and can be used in areas where more bleeding is anticipated
- 32. VASOCONSTRICTOR DIRECTLY ACTING INDIRECTLY ACTING MIXED ACTING CATECHOLAMINES • EPINEPHRINE • NOREPINEPHRINE • DOPAMINE • METHOXAMINE • PHENYLEPHRINE • ISOPROTENEROL • LEVONODEFRIN NON CATECHOLAMINES • TYRAMINE • AMPHETAMINE • METHAMPHETAMINE • HYDROXYAMPHETAMI NE • METARAMINOL • EPHEDRINE
- 33. Acid Dissociation Constant: Onset of action Lipid solubility Anesthetic potency Protein binding Duration of action Vasodilator activity Potency and vasodilating action
- 34. Lignocaine • Amide type of local anesthetic • Prepared by Nils Lofgren in 1943 • FDA approved in 1948 • Metabolised in the liver • Excreted by kidneys • pH of plain solution in 6.5 & with vasoconstrictor 3.5 • EFFECTIVE DENTAL CONCENTRATION IS 2%
- 35. DISPLACEMENT OF Ca+2 FROM SODIUM CHANNEL RECEPTOR SITE BINDING OF LA MOLECULE TO THE RECEPTOR SITE BLOCKADE OF SODIUM CHANNEL DECREASE IN SODIUM CONDUCTANCE DEPRESSION OF RATE OF DEPOLARISATION FAILURE TO ACHIEVE THRESHOLD POTENTIAL LACK OF DEVELOPMENT OF PROPOGATED ACTION CONDUCTION BLOCKADE
- 36. Handbook of local anesthesia by Stanley F. Malamed 7th edition Monhiems local anesthesia and pain control in dental practice 7th edition
- 37. THANKYOU