LOCAL ANESTHESIA presented by deepti awasthi CONTENTS Introduction Definitions History Ideal Properties of LA Mechanism Of Action Classification Constituents.

LOCAL ANESTHESIA presented by deepti awasthi

CONTENTS Introduction Definitions History Ideal Properties of LA Mechanism Of Action Classification Constituents Pharmacokinetics- Uptake, distribution, Metabolism, excretion Vasoconstrictors Local anesthetic agents Topical anesthetics Complication Recent advances. In pediatric dentistry Refere nces 3

INTRODUCTION

DEFINITIONS Acc to Malamed 1980 : Loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings and inhibition of the conduction process in peripheral nerves

Reversible loss of sensation in a body part without the loss of consciousness or the impairment of central control of vital functions. Damle

HISTORY 1860 Albert Nieman was first to isolate cocaine & discovered its anesthetic properties 1884 Karl Koller used cocaine as a topical anesthetic for opthalmological surgical procedures. 1905 Alfred Einhorm developed procaine, 1943 Lidocaine by Lofgren Damle

IDEAL PROPERTIES OF LA 8 Nonirritating to the tissues. Not cause any permanent alteration of nerve. Low systemic toxicity. It must be effective. Time of onset should be short. The duration of action must be enough.

Desirable properties by Bennett Sufficient potency to give complete anesthesia without the use of harmful conc. solutions. No allergic reactions. Stable in solution & undergo biotransformation in the body. Sterile or capable of being sterilized by heat without deterioration.

MECHANISM OF ACTION Acetyl choline theory Calcium displacement theory Surface repulsion theory Membrane expansion theory Specific receptor theory

CLASSIFICATION ESTERS CLASSIFICATION ESTERS Of benzoic acid Cocaine Butacaine Piperocaine Tetracaine Ethyl amino benzoate (benzocaine) hexylcaine Of p-aminobenzoic acid Procaine Chlorprocaine propoxycaine

AMIDES Articaine Bupivacaine Dibucaine Etidocaine Lidocaine Mepivacaine Prilocaine Ropivacaine QUINOLINE Centbucridine

Based on duration of action : 1. Long acting ( 90 + mins ) Bupivacaine + epinephrine Etidocaine Intermediate acting ( 60 mins ) Articaine + epinephrine Lidocaine + epinephrine Mepivacaine + epinephrine Short acting (30 mins) Lidocaine Mepivacaine Prilocaine Malamed

CONSTITUENTS CONSTITUENTS 1. Local anesthetic agents 2. Vasoconstrictors purpose served : Decreased blood flow to the site Absorption of LA into the CVS is slowed. Decreases the risk of LA toxicity. Increased duration of action

3. Reducing agents : To minimize oxidation of vasoconstrictor - sodium metabisulphite 4. Preservative : methyl paraben if allergic- caprylhydrocuprinotoxin. 5. Fungicide : thymol 6. Vehicle : modified ringers soln isotonic vehicle minimizes discomfort during injection. S.Tandon

PHARMACOKINETICS 18 UptakeDistributionBiotransformationExcretion

UPTAKE : All LA produces vasodilation, cocaine only LA producing vasoconstriction. Oral : absorbed poorly from GIT(except cocaine) Topical : absorbed at diff rates I.V. : primary management of ventricular dysrythmia.

DISTRIBUTION Highly perfused organs have higher level. skeletal muscle greatest % of LA The blood level is influenced by factors : Rate of absorption into CVS. Rate of distribution to the tissues. Elimination of the drug. Crosses BBB

METABOLISM Overall toxicity depends upon balance b/w rate of absorption & removal from blood. ESTER : hydrolysed in the plasma by pseudocholinesterase ( Kalow W : hydrolysis of LA by human serum cholinesterase, J Pharmacol exp ther 104: 122-134, 1952)

Chlorprocaine, most rapidly hydrolysed Tetracaine, 16 times slowly hydrolysed Procaine undergoes hydrolysis to PABA,

AMIDE : primary site of biotransformation is Liver. Prilocaine some also in the lung. 70% of a dose of injected lidocaine undergoes biotransformation in patient with normal liver function.

EXCRETION : Kidneys primary excretory organ Esters : appear in very small conc as parent compound in urine Amides : higher % Malamed

VASOCONSTRICTORS DIRECT ACTING : Epinephrine Norepinephrine Levonordefrin Isoproteronol Dopamine Methoxamine phenylephrine

INDIRECT ACTING : Tyramine Amphetamine Methamphetamine Hydroxyamphetamine MIXED : Metaraminol ephedrine

Pyrocatechin derivative epinephrine & norepinephrine Benzol derivative levonordefrine Phenol derivative phenylephrine

Conc. of clinically used VC CONCENTRATION mg/mlTherapeutic use 1:10001.0Emergency- anaphylaxis (IM/SC) 1:10,0000.1Emergency cardiac arrest (IV) 1:100,0000.01LA 1:200,0000.005LA Malamed

LOCAL ANESTHETIC AGENTS

PROCAINE First synthetic injectable LA. Ester type Onset : 6 - 10 mins Produces the most vasodilation, used to aid in breaking arteriospasm.

LIDOCAINE Most commonly used. 1 st amide LA in dentistry By Lofgren, 1943 Onset rapid (2-3 mins) Effective dental conc. -2% Half life 90 mins Topical action 5%

MRD 4 mg/kg or 7mg/kg with epinephrine In dental procedures 2% lidocaine with1:100,000 epinephrine For hemostasis 2% lidocaine with1:50,000 epinephrine

BUPIVACAINE Amide-type local anesthetic Onset of action is slower than lidocaine and anesthesia is long acting. Normally provides 2-4 hours of anesthesia Can be extended in some cases by using solution with epinephrine to 7 hours

2 primary indication- Lengthy procedures -90 mins (eg : full mouth reconstruction, implant surgery) Management of surgery pain. Rarely indicated in children.

MEPIVACAINE AMIDE Introduced into dentistry as 2% soln. containing levonordefrin & 3%without vc Slight vasodilation Onset rapid Mepivacaine plain most used LA in pediatric patients & in geriatric patients.

PRILOCAINE Amide 40% less toxic Orthotoluidine, induces the formation of methemoglobin Cyanosis T/t reversed within 15 mins with administration of 1-2 mg/kg body wt. of 1% methylene blue i.v. over a 5 min period Effective conc. 4%

ARTICAINE Amide type containing a thiophene group. Synthesized in 1969 in Germany, Effective conc. - 4 percent with 1:100,000 epinephrine. Able to diffuse through hard & soft tissues more reliably than other LA. The effect of numbness of soft tissues was longer lasting. IJPD

TOPICAL ANESTHETICS

Topical anesthetic is effective on surface tissues (2-3 mm in depth) to reduce painful needle penetration of the oral mucosa. A variety of agents are available in Gel Liquid Ointment Patch Aerosol forms

Higher conc. Facilitates diffusion of the drug through the mucous membrane. BENZOCAINE :widely used since1903 Odourless, white crystalline powder soluble in alcohol, fatty oils & dilute acids. Absorbed very slowly from oral tssues & wounds. 140 mg/ml

COCAINE HYDROCHLORIDE Highly soluble in water. Onset rapid ( 1 min ) 2 to 10 % Extreme abuse potential _ topical use in dentistry is not recommended. DYCLONINE HYDROCHLORIDE 0.5% Onset 10 mins Duration 1 hr. EMLA LIDOCAINE 2 forms : base- 5% HCl- 2%

CONTRAINDICATIONS PROBLEMDRUGS TO AVOIDALTERNATIVE LA allergyAll LA in same class (eg. ester) Amide Bisulfite allergyVC containing LAWithout VC Atypical plasma cholinesterase estersamides methemoglobinemiaprilocaineOther amide Significant liver prblmAmidesAmides or ester Significant renal prblmAmides or esters Significant CVS diseaseHigh conc. of VC1:200,000 Clinical hyperthyroidismHigh conc. of VC1;200,000

COMPLICATIONS LOCAL Needle breakage Paraesthesia Facial nerve paralysis Trismus Soft tissue injury Hematoma infection Pain on injection Burning on injection Edema Sloughing of tissues Post anesthetic intra oral lesions

SYSTEMIC Overdose Allergy : fever anaphylaxis angioedema urticaria photosensitivity dermatitis idiosyncrasy

RECENT ADVANCES EMLA Lidocaine 2.5 % & prilocaine 2.5 % Intact skin anesthesia, & is used primarily before painful procedures as venipuncture. Routine use circumcision,leg ulcer debridement & in gynaecological procedures 1 hr before

Contraindicated

LOCAL ANESTHESIA presented by deepti awasthi CONTENTS Introduction Definitions History Ideal Properties of LA Mechanism Of Action Classification Constituents.

Documents

introduction slide

tandon slide

lofgren damle slide

deepti awasthi slide

anesthetic properties

gitexcept cocaine topical

constituents constituents

site absorption of la