Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
LOCAL ANESTHESIA 
- Dr. Ibrahim Shaikh 
1st Year MDS Periodontology 
Seminar No. 1 
1 
Guide – Dr. Varsha Rathod.
Local anesthetics are effective means of pain 
control, provided necessary precautions are 
taken along with thorough know...
CONTENTS : 
 Introduction 
 History 
 Neurophysiology 
 Pharmacology of local anesthetics. 
 Pharmacology of vasocons...
4 INTRODUCTION
PAIN : 
 Unpleasant emotional experience usually 
initiated by a noxious stimulus and transmitted 
over a specialized neu...
Methods Of Pain Control : 
1. Removing the cause 
2. Blocking the pathway of painful impulses 
3. Raising the pain thresho...
What Is Anesthesia ? 
 Anesthesia – It is a temporary state consisting 
of unconsciousness, amnesia, analgesia, 
muscle r...
OF LOCAL ANESTHESIA 
8 HISTORY
History : 
 Dentists, not doctors, were responsible for the 
discovery of anesthesia. 
 Dr. Horace Wells (1815-1848) wit...
Controversy : 
10 
 Crawford Long (1815 - 1878) : physician from 
Jefferson, Georgia. 
 Horace Wells (1815-1848) : Denti...
Dr. Horace Wells : 
11 
History of periodontology
Gardner Q. Colton 
12
History of Periodontology 
13 
 December 11, 1844 John Riggs extracted a molar from 
Dr. Wells – The First painless extra...
14 
 John Collins Warren, Professor of surgery, 
Massachusetts General Hospital, Boston. 
 January 20, 1845 – Wells nerv...
Dr. William Morton : 
History of periodontology. 
15 
Helped wells in his failed demonstration and in 1846 consulted 
with...
History of periodontology 
16 
 On September 30, 1846 – 
extracted a patients tooth in 
a painless procedure. 
 On Octob...
$1,00,000 
17 
Horace Wells 
William Morton 
Charles Jackson 
Crawford Long 
History of periodontology
The COCA Leaf : 
 Coca leaves – genus Erythroxylum. 
(Erythroxylaceae family) 
 Erythroxylum coca – highest concentratio...
Cocaine : 
 In 1860 German chemist Albert Niemann 
managed to isolate the active principle, which 
he named cocaine. 
 S...
Sigmund Freud : 
20 
 Sigmund Freud (1856- 
1939) – German military 
experiment, providing 
cocaine to soldiers 
during m...
Carl Koller : 
21 
Sep 11, 1884 - Carl Koller an ophthalmologist 
performed the first operation using local 
anesthetic on...
 Dec 6, 1884 Dr. William Stewart Halsted 
published a report on the first successful nerve 
block, in context of dentistr...
23 
After Cocaine : 
 1905 – Novocaine appeared for the first time and was found 
to be safe and quickly became the stand...
Local Anesthesia : 
 Local Anesthesia has been defined as a loss of 
sensation in a circumscribed area of the body 
cause...
Properties : 
 Should not be irritating to tissues. 
 Should not cause any permanent alteration of nerve 
structure. 
 ...
Bennett’s additional requirements 
: 
 Potency sufficient to give complete anesthesia without the 
use of harmful concent...
27 NEUROPHYSIOLOGY
The Neuron : 
 Structural unit of the nervous system. 
 Transmits messages between the CNS & all parts of 
body. 
 Type...
The Sensory Neuron : 
29 
Handbook of Local Anesthesia, Stanley F. Malamed
The Motor Neuron : 
Handbook of Local Anesthesia, Stanley F. Malamed 
30
The Axon : 
 Long cylinder of neural cytoplasm encased in a thin 
sheath, the nerve membrane, or axolemma. 
 Axoplasm is...
The Nerve Membrane : 
 The nerve membrane is 70 – 80 A° thick. 
 Flexible non stretchable layer consists of two layers o...
 Proteins are primary organizational elements of the 
Handbook of Local Anesthesia, Stanley F. Malamed 
membranes. 
 Pro...
34
Nerve Conduction : 
Handbook of Local Anesthesia, Stanley F. Malamed 
35
Action Of Local Anesthetics : 
 Local Anesthetics interfere with the excitation process in 
nerve membrane by one of the ...
Theories Of Local Anesthetics : 
Handbook of Local Anesthesia, Stanley F. Malamed 
 Acetylcholine theory 
 Ach involved ...
Theories Of Local Anesthetics : 
Handbook of Local Anesthesia, Stanley F. Malamed 
Membrane 
Expansion 
Theory : 
Drug mo...
Theories Of Local Anesthetics : 
 Specific Receptor Theory : 
 Local Anesthetics act by binding to specific 
receptors o...
Classification of Local Anesthetic substances 
according to biological site & mode of action 
Handbook of Local Anesthesia...
Mode Of Action Of LAs : 
 Displacement of Ca ions from the Na channel receptor 
Handbook of Local Anesthesia, Stanley F. ...
OOOO N 
 All Local Anesthetics are amphipathic. 
 The hydrophilic part is an amino derivative of 
ethyl alcohol or aceti...
Dissociation of Local 
Anesthetics : 
 Local anesthetics are basic compounds, 
poorly soluble in water and unstable on 
e...
 Both base and cation exist simultaneously 
RNH+ RN + H+ 
 As the pH decreases, equilibrium shifts to the 
left 
RNH+ > ...
pKa and Anesthesia : 
 pKa (dissociation constant) is the measure of a molecule’s 
Handbook of Local Anesthesia, Stanley ...
 1000 molecules of LA (pKa-7.9) – injected in tissue (pH 7.4) 
 By Henderson-Hasselbalch equation- 75% RNH+ form & 
Hand...
Barriers : 
Handbook of Local Anesthesia, Stanley F. Malamed 
 Peripheral nerve 
composed of hundreds 
to thousands of ti...
FACTOR 
ACTION 
AFFECTED 
DESCRIPTION 
pKa Onset 
Lower pKa = more rapid onset of action, 
more RN molecules present to di...
49 PHARMACOLOGY 
OF LOCAL ANESTHETICS
Classification : 
Based on Chemical structure 
Handbook of Local Anesthesia, Stanley F. Malamed 
 ESTER GROUP 
 Benzoic ...
Procaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
51 
 Vasodilation- clean surgical field difficult to mainta...
Lidocaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
52 
 Compared with procaine, lidocaine possesses 
a signif...
Mepivacaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
53 
 Provide longer duration of anesthesia than most oth...
Prilocaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
54 
 Integral part of EMLA(eutectic mixture of local 
ane...
Articaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
55 
 Clinically, it is claimed that maxillary buccal 
infi...
Bupivacaine & Etidocaine : 
Handbook of Local Anesthesia, Stanley F. Malamed 
56 
 Lengthy dental procedures for which pu...
Topical Anesthetics : 
57 
 Topical anesthetics diffuse through the mucous 
membranes and injured skin to reach the free ...
Pharmacokinetics of Local Anesthetics : 
Handbook of Local Anesthesia, Stanley F. Malamed 
 Uptake 
 Distribution 
 Met...
Uptake 
 All local anesthetics possess some degree of 
vasoactivity; most producing some level of 
vasodilation 
 Ester ...
 Vasodilation leads to an increased rate of absorption of the 
local anesthetic into the blood, thus decreasing the durat...
Distribution of Local Anesthetics : 
 Once in the blood, local anesthetics are distributed to all 
Handbook of Local Anes...
Factors influencing the blood levels 
: 
1) Rate at which the drug is absorbed into the 
Handbook of Local Anesthesia, Sta...
All local anesthetics cross the 
Handbook of Local Anesthesia, Stanley F. Malamed 
blood brain barrier 
All local anesthet...
Metabolism : 
64 
Ester Local Anesthetics: 
 Hydrolyzed in the plasma by the enzyme 
pseudocholinesterase 
 The rate of ...
65 
Esters - Procaine- 
Para amino benzoic acid Diethyl amino alcohol 
Excreted unchanged urine further transformed-urine ...
66 
Amide Local Anesthetics: 
 Primary site of metabolism of amide local anesthetics is 
the liver. 
 Virtually the enti...
67 
Biotransformation : 
Mono ethyl xylidide 
Glycine xylidide 
Xylidide 
Hydroxy xylidide. 
Excreted by kidney . 
Handboo...
68 
 Liver function and hepatic perfusion greatly affect the 
rate of metabolism (biotransformation) of amide local 
anes...
69 
 Metabolism byproducts of amide local anesthetics can 
possess clinical activity if allowed to accumulate in the 
blo...
70 
U.S. Air Force and U.S. Navy pilots are 
grounded for 24 hours following 
administration of Lidocaine due to its mild ...
71 
If the local anesthetic has two “i”s in its name; it’s 
an amide 
Lidocaine 
Prilocaine 
Bupivacaine 
Articaine 
Mepiv...
Composition : 
72 
 Local anesthetic drug –e.g. lignocaine . 
 Vasopressor drug - e.g. adrenaline. 
 Anti-oxidant - egg...
How much LA can be injected : 
73 
 Without adrenaline is : 300mg or 4.4mg/kg 
 With adrenaline : 500mg or 7mg/kg 
 Saf...
Effects of LA on CNS : 
74 
 The pharmacological action of local anesthetics on the 
CNS is depression. 
 At high levels...
Preconvulsive Signs and Symptoms : 
75 
 Numbness of tongue & circumoral regions. 
 Shivering, Slurred speech, Muscular ...
Cardiovascular Effects of LA’s : 
76 
 Local anesthetics have a direct action on the 
myocardium and peripheral vasculatu...
77 
 Local anesthetics decrease myocardial excitation, 
decrease conduction rate and decrease the force of 
contraction 
...
Lung Toxicity : 
78 
 Local anesthetics have a direct relaxant action on bronchial 
smooth muscle. 
 Generally, respirat...
Of Vasoconstrictors. 
79 Pharmacology
Vasoconstrictor’s : 
80 
 All clinically effective injectable L.A have some degree of 
vasodialating activity 
 ↑ absorp...
Classification : 
81 
 Catecholamines : 
 Epinephrine 
 Norepinephrine 
 Levonordefrin 
 Isoproterenol 
 Dopamine 
...
Selection Of Vasoconstrictors : 
82 
 The length of surgical procedure 
Duration of pulpal and soft tissue anesthesia wit...
83 
 Requirement for post operative pain control. 
plain LA produce pulpal anesthesia for short duration 
 Medical Statu...
Contraindications : 
84 
Patients with more significant cardiovascular disease 
(ASA Ш and IV) 
Patients with certain no...
85 Applied Aspects 
Of Local Anesthesia
Which type of LA should be given 
in inflammation? 
86 
• Mepivacaine is suitable for infected areas 
which have 
acidic m...
Allergic to both groups : 
87 
If a pt is sensitive to both groups . 
Antihistamines like diphenhydramine can be 
given fo...
What happens in case of alcoholics & 
smokers? 
88 
• In case of acute alcoholics there is vasodilatation 
present at the ...
Complications : 
89 
 LOCAL 
 Needle breakage 
 Persistent 
anesthesia 
 Facial nerve 
paralysis 
 Trismus 
 Soft-ti...
Overdose : 
90 
• A drug over dose reaction has been defined as those 
clinical signs & symptoms that result from an overl...
91 
 Elevated blood levels of LA may result from one or 
more of the following: 
1. Biotransformation of the drug is usua...
92 
Symptoms: 
Restlessness, Visual disturbances 
Nervous & Auditory disturbances 
Numbness & Metallic taste 
Light-headed...
Allergy : 
93 
• Allergy is a hypersensitive state, acquired through 
exposure to a particular allergen, re-exposure to 
w...
In Local Anesthetics 
94 Future Trends
Centbucridine : 
95 
Quinoline derivative 
 Five to eight times the potency of lidocaine 
Rapid onset and an equivalent...
Ropivacaine : 
96 
 Long acting amide anesthetic 
 Structurally similar to mepivacaine and bupivacaine. 
 Unique in tha...
Carbonated Local Anesthetics : 
97 
 Carbon dioxide enhances diffusion of local anesthetic 
through nerve membranes, prov...
98 
 The problem = if the carbonated LA agent is not 
injected almost immediately after opening of the 
vial the CO2 will...
Electronic Dental Anesthesia : 
99 
 A hand held electrode is placed at 
the needle penetration site, 
providing a very l...
Reference : 
100 
 Handbook of Local Anesthesia ; Stanley F. 
Malamed. 
 Monheim’s Handbook of Local Anesthesia. 
 Hist...
…for the patience. 
101 THANK YOU
Upcoming SlideShare
Loading in …5
×
Upcoming SlideShare
Monheims local anesthesia and pain control in dental practice pdf
Next
Download to read offline and view in fullscreen.

106

Share

Download to read offline

Local anesthesia

Download to read offline

Complete presentation on local anesthesia, including history, pharmacokinetics, vasoconstrictors, etc

Related Books

Free with a 30 day trial from Scribd

See all

Related Audiobooks

Free with a 30 day trial from Scribd

See all

Local anesthesia

  1. 1. LOCAL ANESTHESIA - Dr. Ibrahim Shaikh 1st Year MDS Periodontology Seminar No. 1 1 Guide – Dr. Varsha Rathod.
  2. 2. Local anesthetics are effective means of pain control, provided necessary precautions are taken along with thorough knowledge of the drugs. 2
  3. 3. CONTENTS :  Introduction  History  Neurophysiology  Pharmacology of local anesthetics.  Pharmacology of vasoconstrictors.  Clinical aspects of local anesthetics.  Future trends. 3
  4. 4. 4 INTRODUCTION
  5. 5. PAIN :  Unpleasant emotional experience usually initiated by a noxious stimulus and transmitted over a specialized neural network to the central nervous system where it is interpreted as such. Monheim’s Handbook of Local Anesthesia 5
  6. 6. Methods Of Pain Control : 1. Removing the cause 2. Blocking the pathway of painful impulses 3. Raising the pain threshold 4. Preventing pain reaction by cortical depression 5. Using psychosomatic methods 6 Monheim’s Handbook of Local Anesthesia
  7. 7. What Is Anesthesia ?  Anesthesia – It is a temporary state consisting of unconsciousness, amnesia, analgesia, muscle relaxation and loss of autonomic reflexes.  Proposed by Oliver Wendell Holmes in 1846. 7
  8. 8. OF LOCAL ANESTHESIA 8 HISTORY
  9. 9. History :  Dentists, not doctors, were responsible for the discovery of anesthesia.  Dr. Horace Wells (1815-1848) with nitrous oxide in 1844  Dr. William Thomas Green Morton (1819- 1868) with ether in 1846. 9 History of periodontology
  10. 10. Controversy : 10  Crawford Long (1815 - 1878) : physician from Jefferson, Georgia.  Horace Wells (1815-1848) : Dentist from Hartford , Connecticut.  William Morton (1819-1868) : Dentist from Boston, Massachusetts. History of periodontology
  11. 11. Dr. Horace Wells : 11 History of periodontology
  12. 12. Gardner Q. Colton 12
  13. 13. History of Periodontology 13  December 11, 1844 John Riggs extracted a molar from Dr. Wells – The First painless extraction of the modern era of medicine.
  14. 14. 14  John Collins Warren, Professor of surgery, Massachusetts General Hospital, Boston.  January 20, 1845 – Wells nervously attempted to extract a student’s tooth in front of an audience of incredulous staff and students. History of periodontology
  15. 15. Dr. William Morton : History of periodontology. 15 Helped wells in his failed demonstration and in 1846 consulted with Charles Jackson, professor of chemistry about other drugs that could have a similar effect. Jackson suggested ether.
  16. 16. History of periodontology 16  On September 30, 1846 – extracted a patients tooth in a painless procedure.  On October 16, performed a successful demonstration at Massachusetts General Hospital in which he removed a tumor from the neck of a patient.
  17. 17. $1,00,000 17 Horace Wells William Morton Charles Jackson Crawford Long History of periodontology
  18. 18. The COCA Leaf :  Coca leaves – genus Erythroxylum. (Erythroxylaceae family)  Erythroxylum coca – highest concentration of alkaloid known as cocaine in its leaves (up to 0.7 – 1.8% by weight)  Arhuaco, a tribe from the Negro river region, were the first to discover the properties of this drug.  In 1653, Bernabé Cobo, a Spanish Jesuit mentioned in one of his manuscripts that toothaches can be alleviated by chewing coca leaves 18 History of the development & evolution of local anesthesia since the coca leaf. Calatayud, Jesus Journal of Anesthesiology, June 2003:98 – 6:1503-1508
  19. 19. Cocaine :  In 1860 German chemist Albert Niemann managed to isolate the active principle, which he named cocaine.  Steps were then taken to apply it as the first local anesthetic by several people. Lossen(1865),Thomas Moreno(1868),Basil Von Anrep (1880) 19 History of the development & evolution of local anesthesia since the coca leaf. Calatayud, Jesus Journal of Anesthesiology, June 2003:98 – 6:1503-1508
  20. 20. Sigmund Freud : 20  Sigmund Freud (1856- 1939) – German military experiment, providing cocaine to soldiers during maneuvers to help them overcome the hardships of military campaigns.  Drug induced a euphoric stage that lifted him out of his periods of depression. History of periodontology
  21. 21. Carl Koller : 21 Sep 11, 1884 - Carl Koller an ophthalmologist performed the first operation using local anesthetic on a patient with glaucoma. History of the development & evolution of local anesthesia since the coca leaf. Calatayud, Jesus Journal of Anesthesiology, June 2003:98 – 6:1503-1508
  22. 22.  Dec 6, 1884 Dr. William Stewart Halsted published a report on the first successful nerve block, in context of dentistry.  Dr. Nash of New York was able to block the infraorbital plexus with approx. 0.5ml of 4% cocaine hydrochloride to obturate an upper incisor.  Dr. Halsted on the other hand blocked the inferior dental nerve in a medical student using the same solution. History of the development & evolution of local anesthesia since the coca leaf. Calatayud, Jesus Journal of Anesthesiology, June 2003:98 – 6:1503-1508 22
  23. 23. 23 After Cocaine :  1905 – Novocaine appeared for the first time and was found to be safe and quickly became the standard local anesthesia. (rechristened procaine in United states)  1943-1946 – Nils Löfgren & Bengt Lundquist developed a xylidine derivative they called lidocaine.  1957 – Bo af Ekenstam et al. synthesized mepivacaine and History of the development & evolution of local anesthesia since the coca leaf. Calatayud, Jesus Journal of Anesthesiology, June 2003:98 – 6:1503-1508 bupivacaine.  1969 – prilocaine : Nils Löfgren & cläes Tegner
  24. 24. Local Anesthesia :  Local Anesthesia has been defined as a loss of sensation in a circumscribed area of the body caused by a depression of excitation in nerve endings or an inhibition of the conduction process in peripheral nerves.  It produces this loss of sensation without inducing a loss of consciousness. Handbook of Local Anesthesia, Stanley F. Malamed 24
  25. 25. Properties :  Should not be irritating to tissues.  Should not cause any permanent alteration of nerve structure.  Should have very low systemic toxicity.  Effective regardless of mode of administration.  Short time of onset of anesthesia.  Long duration of action of anesthetic effect. Handbook of Local Anesthesia, Stanley F. Malamed 25
  26. 26. Bennett’s additional requirements :  Potency sufficient to give complete anesthesia without the use of harmful concentrated solutions.  Relatively free from producing allergic reactions.  Should be stable in solution and should readily undergo biotransformation in the body.  Should either be sterile or should be capable of being sterilized by heat without deterioration. Handbook of Local Anesthesia, Stanley F. Malamed 26
  27. 27. 27 NEUROPHYSIOLOGY
  28. 28. The Neuron :  Structural unit of the nervous system.  Transmits messages between the CNS & all parts of body.  Types – a) Sensory b) Motor 28 Handbook of Local Anesthesia, Stanley F. Malamed
  29. 29. The Sensory Neuron : 29 Handbook of Local Anesthesia, Stanley F. Malamed
  30. 30. The Motor Neuron : Handbook of Local Anesthesia, Stanley F. Malamed 30
  31. 31. The Axon :  Long cylinder of neural cytoplasm encased in a thin sheath, the nerve membrane, or axolemma.  Axoplasm is separated from extracellular fluids by a Handbook of Local Anesthesia, Stanley F. Malamed continuous nerve membrane.  Sensory nerve excitability and conduction are both attributed to changes developed within the nerve membrane. 31
  32. 32. The Nerve Membrane :  The nerve membrane is 70 – 80 A° thick.  Flexible non stretchable layer consists of two layers of Handbook of Local Anesthesia, Stanley F. Malamed lipid molecules 32
  33. 33.  Proteins are primary organizational elements of the Handbook of Local Anesthesia, Stanley F. Malamed membranes.  Proteins are classified as transport proteins and receptor sites.  Channel proteins are continous pores through the membrane allowing some ions (Na+, K+, Ca++) to pass passively.  Other channels are gated, permitting ion flow only when the gates are open. 33
  34. 34. 34
  35. 35. Nerve Conduction : Handbook of Local Anesthesia, Stanley F. Malamed 35
  36. 36. Action Of Local Anesthetics :  Local Anesthetics interfere with the excitation process in nerve membrane by one of the following mechanism: 1. Altering the basic resting potential of the nerve Handbook of Local Anesthesia, Stanley F. Malamed membrane. 2. Altering the threshold potential 3. Decreasing the rate of depolarization 4. Prolonging the rate of repolarization  It has been established that the primary effects of local anesthetics occur during the depolarization phase of the action potential.¹ 36
  37. 37. Theories Of Local Anesthetics : Handbook of Local Anesthesia, Stanley F. Malamed  Acetylcholine theory  Ach involved in nerve conduction  Calcium displacement theory  Ca2+ displaced from membrane site, alters Na2+ permeability  Surface charge (repulsion) theory  Cationic drug molecules bind to nerve membrane making it more positive, thus increasing the threshold potential causing decreased excitability 37
  38. 38. Theories Of Local Anesthetics : Handbook of Local Anesthesia, Stanley F. Malamed Membrane Expansion Theory : Drug molecule penetrates the lipid portion of membrane & brings about a change in the configuration of lipoprotein matrix, preventing Na ions permeability thereby inhibiting neural excitation. 38
  39. 39. Theories Of Local Anesthetics :  Specific Receptor Theory :  Local Anesthetics act by binding to specific receptors on the sodium channel.  Action of the drug is direct & not mediated by some change in the general properties of the cell membrane.  Specific receptor site for local anesthetic agents exist in the sodium channel either on its external surface or on the internal axoplasmic surface.  Once the local anesthetic has gained access to the receptors, permeability to sodium ions is decreased or eliminated & nerve conduction is eliminated. Handbook of Local Anesthesia, Stanley F. Malamed 39
  40. 40. Classification of Local Anesthetic substances according to biological site & mode of action Handbook of Local Anesthesia, Stanley F. Malamed 40 CLASS A CLASS B CLASS C CLASS D
  41. 41. Mode Of Action Of LAs :  Displacement of Ca ions from the Na channel receptor Handbook of Local Anesthesia, Stanley F. Malamed site,  Binding of the local anesthetic molecule to this receptor site  Blockade of the sodium channel  Decrease in sodium conductance  Decrease of the rate of electrical depolarization  Failure to achieve the threshold potential level  Lack of development of propagated action potentials  Conduction blockade. 41
  42. 42. OOOO N  All Local Anesthetics are amphipathic.  The hydrophilic part is an amino derivative of ethyl alcohol or acetic acid.  The lipophilic part is the largest. Aromatic in structure, it is derived from benzoic acid, aniline, or thiophene.  The structure is completed by an intermediate hydrocarbon chain containing either an ester or an amide linkage. Handbook of Local Anesthesia, Stanley F. Malamed 42
  43. 43. Dissociation of Local Anesthetics :  Local anesthetics are basic compounds, poorly soluble in water and unstable on exposure to air.  They combine with acids to form local anesthetic salts, which are water-soluble and stable.  Local anesthetic are dissolved in either sterile water or saline  In this solution, it exists as uncharged molecules (RN) called base and positively charged molecules (RNH+) called the cation. Handbook of Local Anesthesia, Stanley F. Malamed 43
  44. 44.  Both base and cation exist simultaneously RNH+ RN + H+  As the pH decreases, equilibrium shifts to the left RNH+ > RN + H+  As the pH increases, equilibrium shifts to the right RNH+ < RN + H+ Handbook of Local Anesthesia, Stanley F. Malamed 44
  45. 45. pKa and Anesthesia :  pKa (dissociation constant) is the measure of a molecule’s Handbook of Local Anesthesia, Stanley F. Malamed affinity for hydrogen ions.  When pH = pKa, the drug exists in exactly 50% RNH+ and 50% RN form  The two factors involved in the action of a local anesthetic are diffusion of the drug through the nerve sheath and binding at the receptor site in the ion channel  The uncharged free base form RN is responsible for the diffusion through the nerve sheath. 45
  46. 46.  1000 molecules of LA (pKa-7.9) – injected in tissue (pH 7.4)  By Henderson-Hasselbalch equation- 75% RNH+ form & Handbook of Local Anesthesia, Stanley F. Malamed 25% RN form  Diffusibility & binding are responsible for LA effectiveness, but the diffusibility is much more important in actual practice. 46
  47. 47. Barriers : Handbook of Local Anesthesia, Stanley F. Malamed  Peripheral nerve composed of hundreds to thousands of tightly packed axons.  Endoneurium  Perineurium – Fascicle  Perilemma – innermost layer of perineurium  Epineurium  Epineural sheath or nerve sheath 47
  48. 48. FACTOR ACTION AFFECTED DESCRIPTION pKa Onset Lower pKa = more rapid onset of action, more RN molecules present to diffuse through nerve sheath, thus onset time is decreased Lipid solubility Anesthetic potency Increased lipid solubility = increased potency Protein binding Duration Increased protein binding allows anesthetic cations (RNH+) to be more firmly attached to protein located at receptor sites, thus duration of action is increased Tissue diffusibility Onset Increased diffusibility = decreased time of onset Vasodilator activity Anesthetic potency and duration Greater vasodilator activity = increased blood flow to region = rapid removal of anesthetic molecules from injection site, thus decreased anesthetic potency and Handbdooekc oref Laosceadl A dneusrtahetisoian, Stanley F. Malamed 48
  49. 49. 49 PHARMACOLOGY OF LOCAL ANESTHETICS
  50. 50. Classification : Based on Chemical structure Handbook of Local Anesthesia, Stanley F. Malamed  ESTER GROUP  Benzoic acid esters  Benzocaine, Cocaine, Butacaine, Tetracaine, Hexylcaine, Piperocaine  Para amino benzoic acid esters  Procaine, Chloroprocaine, Propoxycaine  AMIDE GROUP  Lignocaine, Bupivacaine, Mepivacaine, Prilocaine, Articaine, Dibucaine, Etidocaine, Ropivacaine  QUINOLONE  Centbucridine 50
  51. 51. Procaine : Handbook of Local Anesthesia, Stanley F. Malamed 51  Vasodilation- clean surgical field difficult to maintain because of increased bleeding.  Procaine is used in cases of inadvertent intra-arterial(IA) injection of a drug; vasodilating properties are used to aid in breaking arteriospasm.
  52. 52. Lidocaine : Handbook of Local Anesthesia, Stanley F. Malamed 52  Compared with procaine, lidocaine possesses a significantly more rapid onset of action, produces more profound anesthesia, has a longer duration of action, and has a greater potency.
  53. 53. Mepivacaine : Handbook of Local Anesthesia, Stanley F. Malamed 53  Provide longer duration of anesthesia than most other local anesthetics when the drug is administered without a vasoconstrictor.  Mepivacaine plain is the most used local anesthetic in pediatric patients & is often quite appropriate in the management of geriatric patients.
  54. 54. Prilocaine : Handbook of Local Anesthesia, Stanley F. Malamed 54  Integral part of EMLA(eutectic mixture of local anesthetics) cream, which permits the anesthetics to penetrate the imposing anatomic barrier of intact skin.  Prilocaine plain frequently is able to provide anesthesia that is equal in duration to that obtained from lidocaine or mepivacaine with a vasoconstrictor.
  55. 55. Articaine : Handbook of Local Anesthesia, Stanley F. Malamed 55  Clinically, it is claimed that maxillary buccal infiltration of Articaine, provides palatal soft-tissue anesthesia, obliterating the need for the more traumatic palatal anesthesia.  Also claimed that it can provide pulpal and lingual anesthesia when administered by infiltration in adult mandible.
  56. 56. Bupivacaine & Etidocaine : Handbook of Local Anesthesia, Stanley F. Malamed 56  Lengthy dental procedures for which pulpal anesthesia in excess of 90 minutes is necessary.  Difference between the two is that Etidocaine has an onset of action of about 3 minutes, whereas Bupivacaine has an onset of 6 to 10 minutes.
  57. 57. Topical Anesthetics : 57  Topical anesthetics diffuse through the mucous membranes and injured skin to reach the free nerve endings.  But the diffusion is limited and they are rapidly absorbed in the circulation, thus effective block is not obtained.  Thus, to increase their efficacy, their concentration is increased.  5% or 10% lidocaine,1% or 2% tetracaine-most common Handbook of Local Anesthesia, Stanley F. Malamed
  58. 58. Pharmacokinetics of Local Anesthetics : Handbook of Local Anesthesia, Stanley F. Malamed  Uptake  Distribution  Metabolism (Biotransformation)  Excretion 58
  59. 59. Uptake  All local anesthetics possess some degree of vasoactivity; most producing some level of vasodilation  Ester local anesthetics are potent vasodilating drugs  Cocaine is the only local anesthetic that consistently produces vasoconstriction  initial vasodilation  intense vasoconstriction Handbook of Local Anesthesia, Stanley F. Malamed 59
  60. 60.  Vasodilation leads to an increased rate of absorption of the local anesthetic into the blood, thus decreasing the duration and depth of pain control while increasing the anesthetic blood concentration and potential for overdose (toxic reaction) Handbook of Local Anesthesia, Stanley F. Malamed 60
  61. 61. Distribution of Local Anesthetics :  Once in the blood, local anesthetics are distributed to all Handbook of Local Anesthesia, Stanley F. Malamed tissues  Brain, head, liver, lungs, kidneys and spleen have high levels of local anesthetics due to their high level of perfusion  Skeletal muscle has the highest level because it has the largest mass of tissue in the body 61
  62. 62. Factors influencing the blood levels : 1) Rate at which the drug is absorbed into the Handbook of Local Anesthesia, Stanley F. Malamed cardiovascular system. 2) Rate of distribution from the vascular compartment to the tissues. 3) Elimination of the drug through metabolic or excretory pathways. 62
  63. 63. All local anesthetics cross the Handbook of Local Anesthesia, Stanley F. Malamed blood brain barrier All local anesthetics cross the placenta and enter the blood stream of the developing fetus 63
  64. 64. Metabolism : 64 Ester Local Anesthetics:  Hydrolyzed in the plasma by the enzyme pseudocholinesterase  The rate of hydrolysis is related to the degree of toxicity  Tetracaine is hydrolyzed the slowest which makes it 16 times more toxic than Chloroprocaine which is hydrolyzed the fastest Slower Hydrolyzation = Toxicity
  65. 65. 65 Esters - Procaine- Para amino benzoic acid Diethyl amino alcohol Excreted unchanged urine further transformed-urine Handbook of Local Anesthesia, Stanley F. Malamed
  66. 66. 66 Amide Local Anesthetics:  Primary site of metabolism of amide local anesthetics is the liver.  Virtually the entire metabolic process occurs in the liver for Lidocaine, Mepivicaine, Articaine, Bupivacaine and Etidocaine.  Prilocaine is metabolized in the liver and lung. Handbook of Local Anesthesia, Stanley F. Malamed
  67. 67. 67 Biotransformation : Mono ethyl xylidide Glycine xylidide Xylidide Hydroxy xylidide. Excreted by kidney . Handbook of Local Anesthesia, Stanley F. Malamed
  68. 68. 68  Liver function and hepatic perfusion greatly affect the rate of metabolism (biotransformation) of amide local anesthetics  Significant liver dysfunction or heart failure represents a relative contraindication to the use of amide local anesthetics  Articaine has a shorter half-life than other amides because a portion of its metabolism occurs in the blood by plasma cholinesterase Handbook of Local Anesthesia, Stanley F. Malamed
  69. 69. 69  Metabolism byproducts of amide local anesthetics can possess clinical activity if allowed to accumulate in the blood  All local anesthetics have the ability to cause sedation. Handbook of Local Anesthesia, Stanley F. Malamed
  70. 70. 70 U.S. Air Force and U.S. Navy pilots are grounded for 24 hours following administration of Lidocaine due to its mild effects of sedation and/or drowsiness Handbook of Local Anesthesia, Stanley F. Malamed
  71. 71. 71 If the local anesthetic has two “i”s in its name; it’s an amide Lidocaine Prilocaine Bupivacaine Articaine Mepivacaine Handbook of Local Anesthesia, Stanley F. Malamed
  72. 72. Composition : 72  Local anesthetic drug –e.g. lignocaine .  Vasopressor drug - e.g. adrenaline.  Anti-oxidant - egg Sodium meta bi sulfite.  Germicide, Preservative – e.g. methyl paraben.  For isotonicity – Normal Saline .  Distilled water to equal the desired amount . Handbook of Local Anesthesia, Stanley F. Malamed
  73. 73. How much LA can be injected : 73  Without adrenaline is : 300mg or 4.4mg/kg  With adrenaline : 500mg or 7mg/kg  Safe dose adrenaline : 0.2mg/visit 2% Lignocaine - 2g in 100 ml 2000mg - 100 ml 20 mg - 1ml 1 mg - 1/20ml 500mg = 1/20  500 = 25ml can be given safely for a normal pt Handbook of Local Anesthesia, Stanley F. Malamed
  74. 74. Effects of LA on CNS : 74  The pharmacological action of local anesthetics on the CNS is depression.  At high levels, local anesthetics will produce tonic-clonic convulsions.  Procaine, Lidocaine, Mepivacaine, Prilocaine and Cocaine generally produce anti-convulsant properties; this occurs at a blood level considerably below that at which the same drugs cause seizures. Handbook of Local Anesthesia, Stanley F. Malamed
  75. 75. Preconvulsive Signs and Symptoms : 75  Numbness of tongue & circumoral regions.  Shivering, Slurred speech, Muscular twitching.  Visual/auditory disturbances.  Dizziness, Drowsiness, Disorientation & Tremors.  If excitation or sedation occurs in the first 5 to 10 minutes after local anesthetic delivery, it should serve as a warning that convulsive activity could be possible Handbook of Local Anesthesia, Stanley F. Malamed
  76. 76. Cardiovascular Effects of LA’s : 76  Local anesthetics have a direct action on the myocardium and peripheral vasculature  CVS is more resistant to the effects local anesthetics than the CNS  Increased local anesthetic blood levels result in decreased myocardial depolarization, however, no change in resting membrane potential and no prolongation of the stages of repolarization Handbook of Local Anesthesia, Stanley F. Malamed
  77. 77. 77  Local anesthetics decrease myocardial excitation, decrease conduction rate and decrease the force of contraction  Lidocaine is used therapeutically for pre-ventricular contractions (PVCs) and ventricular tachycardia  Local anesthetics cause hypotension from the direct relaxant action on vascular smooth muscle Handbook of Local Anesthesia, Stanley F. Malamed
  78. 78. Lung Toxicity : 78  Local anesthetics have a direct relaxant action on bronchial smooth muscle.  Generally, respiratory function is unaffected by local anesthetics until near overdose levels are achieved.  Skeletal muscle will heal within two weeks of being injected with local anesthetic.  Longer acting local anesthetics (Bupivacaine) produce more damage to skeletal muscle than do shorter acting agents. Handbook of Local Anesthesia, Stanley F. Malamed
  79. 79. Of Vasoconstrictors. 79 Pharmacology
  80. 80. Vasoconstrictor’s : 80  All clinically effective injectable L.A have some degree of vasodialating activity  ↑ absorption of L.A into CVS → removal from injection site  Rapid diffusion of L.A from injection site → ↓ duration of action & depth of anesthesia.  Higher plasma level of L.A → ↑ risk of toxicity  ↑ bleeding at injection site.  Addition of vasoconstrictor to L.A..  Constriction of blood vessels → ↓ tissue perfusion  Slow absorption into CVS → low anesthetic blood level → ↓ risk of toxicity.  Higher volume of L.A around nerve → ↑ duration of action  ↓ bleeding at injection site Handbook of Local Anesthesia, Stanley F. Malamed
  81. 81. Classification : 81  Catecholamines :  Epinephrine  Norepinephrine  Levonordefrin  Isoproterenol  Dopamine  Noncatecholamines :  Amphetamine  Methamphetamine  Ephedrine  Mephentermine  Hydroxyamphetamine  Metaraminol  Methoxamine Handbook of Local Anesthesia, Stanley F. Malamed
  82. 82. Selection Of Vasoconstrictors : 82  The length of surgical procedure Duration of pulpal and soft tissue anesthesia with 2% lidocaine lasts for only 10 min; the addition of 1:50,000, 1:80,000,1:100,000,increases this to app 60 min  Requirement for haemostasis during surgical procedure. Epinephrine is effective in preventing blood loss during surgical procedures, however it also produces rebound vasodilatory effect. Handbook of Local Anesthesia, Stanley F. Malamed
  83. 83. 83  Requirement for post operative pain control. plain LA produce pulpal anesthesia for short duration  Medical Status of the Patient. Benefits and risk of using LA with vasoconstrictor should be weighed against benefits and risks of using plain LA in medically compromised patients Handbook of Local Anesthesia, Stanley F. Malamed
  84. 84. Contraindications : 84 Patients with more significant cardiovascular disease (ASA Ш and IV) Patients with certain non-cardiovascular diseases (e.g., thyroid dysfunction , and sulfite sensitivity) Patients receiving Monoamine oxidases inhibitors, Tricyclic antidepressant , and phenothiazines Handbook of Local Anesthesia, Stanley F. Malamed
  85. 85. 85 Applied Aspects Of Local Anesthesia
  86. 86. Which type of LA should be given in inflammation? 86 • Mepivacaine is suitable for infected areas which have acidic medium , because it has less pKa (7.6)
  87. 87. Allergic to both groups : 87 If a pt is sensitive to both groups . Antihistamines like diphenhydramine can be given for Local anesthetic action
  88. 88. What happens in case of alcoholics & smokers? 88 • In case of acute alcoholics there is vasodilatation present at the site so rapid absorption of LA into circulation resulting in decreased depth and decreased duration of anesthesia • In cases of chronic alcoholics the pain threshold is raised also resulting in decreased depth of anesthesia & need for larger doses which may lead to increased chances of overdose reactions • In smokers , there is peripheral vasoconstriction present = increased duration of action and increased intensity of LA
  89. 89. Complications : 89  LOCAL  Needle breakage  Persistent anesthesia  Facial nerve paralysis  Trismus  Soft-tissue injury  Hematoma  Pain on injection  Burning on injection  Infection, edema  Sloughing of tissues  SYSTEMIC  Overdose  Allergy  Syncope Handbook of Local Anesthesia, Stanley F. Malamed
  90. 90. Overdose : 90 • A drug over dose reaction has been defined as those clinical signs & symptoms that result from an overly high blood level of drug in various target organs and tissues. • Under normal condition there is a constant absorption of local anesthetic from the site of deposition into the CVS & a constant removal of drug from the blood by the liver. Handbook of Local Anesthesia, Stanley F. Malamed
  91. 91. 91  Elevated blood levels of LA may result from one or more of the following: 1. Biotransformation of the drug is usually slow 2. The unbiotransformed drug is too slowly eliminated from the body through the kidneys. 3. Too large a total dose is administered 4. Absorption from the injection site is unusually rapid 5. Inadvertent intravascular administration occurs Handbook of Local Anesthesia, Stanley F. Malamed
  92. 92. 92 Symptoms: Restlessness, Visual disturbances Nervous & Auditory disturbances Numbness & Metallic taste Light-headedness and dizziness Drowsiness and disorientation Losing consciousness Sensation of twitching (before actual twitching is observed) Handbook of Local Anesthesia, Stanley F. Malamed
  93. 93. Allergy : 93 • Allergy is a hypersensitive state, acquired through exposure to a particular allergen, re-exposure to which produces a heightened capacity to react .  Allergens in LOCAL ANESTHETICS : 1. Esters - usually to the Para-amino-benzoic-acid product 2. Na bisulfite or metabisulfite - found in anesthetics as preservatives for vasoconstrictors, antioxidants 3. Methylparaben - no longer used as preservative. Handbook of Local Anesthesia, Stanley F. Malamed
  94. 94. In Local Anesthetics 94 Future Trends
  95. 95. Centbucridine : 95 Quinoline derivative  Five to eight times the potency of lidocaine Rapid onset and an equivalent duration of action Does not affect the central nervous system or cardiovascular system Handbook of Local Anesthesia, Stanley F. Malamed
  96. 96. Ropivacaine : 96  Long acting amide anesthetic  Structurally similar to mepivacaine and bupivacaine.  Unique in that it is prepared as an isomer rather than as a racemic mixture.  Has demonstrated decreased cardiotoxicity.  Potential for use in dentistry appears great, but awaits clinical evaluation. Handbook of Local Anesthesia, Stanley F. Malamed
  97. 97. Carbonated Local Anesthetics : 97  Carbon dioxide enhances diffusion of local anesthetic through nerve membranes, providing a more rapid onset of nerve block .  As CO2 diffuses through the nerve membrane, intracellular pH is decreased, raising the intracellular concentration of charged cations (RNH+) Since the cationic form of the drug does not readily diffuse out of the nerve, the anesthetic becomes concentrated within the nerve trunk (termed “ion trapping”), providing a longer duration of anesthesia. Handbook of Local Anesthesia, Stanley F. Malamed
  98. 98. 98  The problem = if the carbonated LA agent is not injected almost immediately after opening of the vial the CO2 will diffuse out of solution, significantly diminishing the solution’s effectiveness. Handbook of Local Anesthesia, Stanley F. Malamed
  99. 99. Electronic Dental Anesthesia : 99  A hand held electrode is placed at the needle penetration site, providing a very localized area of intense anesthesia, permitting both the painless penetration of intraoral soft tissues with dental needles and administration of local anesthetics Handbook of Local Anesthesia, Stanley F. Malamed
  100. 100. Reference : 100  Handbook of Local Anesthesia ; Stanley F. Malamed.  Monheim’s Handbook of Local Anesthesia.  History of Periodontology ; Fermin carranza, Vincenzo Guerini  History of the development & evolution of local anesthesia since the coca leaf; Calatayud, Jesus, Journal of Anesthesiology, June 2003:98-6: 1503-1508
  101. 101. …for the patience. 101 THANK YOU
  • arnab1989

    Jul. 13, 2021
  • LnPHimamBathusha

    Jul. 13, 2021
  • RaniaHabib6

    Jul. 8, 2021
  • SusiSusitha

    Jul. 1, 2021
  • DishithaReddy

    Apr. 16, 2021
  • ZebaNaaz9

    Feb. 17, 2021
  • RishithaChitithti

    Dec. 2, 2020
  • VarshithaReddy8

    Oct. 12, 2020
  • Sairarosepaul

    Jul. 16, 2020
  • SumanKathungal1

    Jul. 8, 2020
  • YatinPatel74

    May. 13, 2020
  • KavyaVasanthakumar

    May. 1, 2020
  • KritiPatel3

    Apr. 7, 2020
  • Pratikhya25

    Jan. 16, 2020
  • LubnaAlward

    Dec. 3, 2019
  • ashraftashtoush

    Nov. 10, 2019
  • AliALkhaiya

    Oct. 23, 2019
  • AlishaBhamani

    Oct. 13, 2019
  • KanikaMali1

    Aug. 22, 2019
  • MeharFatima8

    Aug. 21, 2019

Complete presentation on local anesthesia, including history, pharmacokinetics, vasoconstrictors, etc

Views

Total views

13,919

On Slideshare

0

From embeds

0

Number of embeds

5

Actions

Downloads

659

Shares

0

Comments

0

Likes

106

×