LOCAL ANESTHESIA presented by deepti awasthi

2. LOCAL ANESTHESIA presented by deeptiawasthi

3. 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 • References

4. INTRODUCTION

5. 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

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

7. 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

8. IDEAL PROPERTIES OF LA

9. Desirable properties by Bennett

10. MECHANISM OF ACTION

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

14. AMIDES • Articaine • Bupivacaine • Dibucaine • Etidocaine • Lidocaine • Mepivacaine • Prilocaine • Ropivacaine QUINOLINE • Centbucridine

15. Based on duration of action : • 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

16. CONSTITUENTS • Local anesthetic agents • 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

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

18. PHARMACOKINETICS

19. 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.

20. 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

21. 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)

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

23. 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.

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

25. VASOCONSTRICTORS • DIRECT ACTING : • Epinephrine • Norepinephrine • Levonordefrin • Isoproteronol • Dopamine • Methoxamine • phenylephrine

26. INDIRECT ACTING : • Tyramine • Amphetamine • Methamphetamine • Hydroxyamphetamine • MIXED : • Metaraminol • ephedrine

27. Pyrocatechin derivative – epinephrine & norepinephrine • Benzol derivative – levonordefrine • Phenol derivative – phenylephrine

28. Conc. of clinically used VC Malamed

29. LOCAL ANESTHETIC AGENTS

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

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

33. 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

34. 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

35. 2 primary indication- • Lengthy procedures -90 mins (eg : full mouth reconstruction, implant surgery) • Management of surgery pain. • Rarely indicated in children.

36. 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.

37. 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%

38. 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

39. TOPICAL ANESTHETICS

40. 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

41. 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

42. 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%

43. CONTRAINDICATIONS

44. 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

45. SYSTEMIC • Overdose • Allergy : fever anaphylaxis angioedemaurticaria photosensitivity dermatitis • idiosyncrasy

46. 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

47. Contraindicated <6mths possibility of prilocaine inducing methemoglobinemia.

48. ROPIVACAINE– Long acting amide, has greater safety margin , less toxicity than bupivicaine. • pH ALTERATION- sodium bicarbonate is being added immediate to injection , which makes solution alkaline and thus increases its absorption into nerve. • Provides more rapid onset

49. CENTBUCRIDINE- • Quinoline derivative • 5-8 times more potent • Significantly it does not affect the CNS, CVS adversely • Subarachnoid & extradural anesthesia(SuriYv et al : double blind study on centbucridine, indian J mer res 76:875-881 , 1982) • Intravenous regional anesthesia & intaocular surgery.

50. HYALURONIDASE- Breaks down intercellular cement. Permits injected soln. to spread & penetrate tissues