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1st yr Class for Local Anesthesia - 1- NKC.ppt

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Pharmacology of local anesthetic agents

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Pharmacology of Local anaesthetic Pharmacology of Local anaesthetic agents agents
05/31/25 05/31/25 2 2 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents • A Local Anaesthetic Agent reversibly blocks A Local Anaesthetic Agent reversibly blocks nerve conduction beyond the point of application, nerve conduction beyond the point of application, when applied locally in the appropriate concentration. when applied locally in the appropriate concentration. • Drugs that produce transient and reversible loss of sensation or feeling in a circumscribed area of the body without loss of consciousness. • Safer than General Anesthesia Safer than General Anesthesia • Widely used Widely used
05/31/25 05/31/25 3 3 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents History History • Cocaine Cocaine-Mid 19 -Mid 19th th century in Europe and America receive century in Europe and America receive attention, Around 1860 Albert Niemann isolated and 20 yrs later attention, Around 1860 Albert Niemann isolated and 20 yrs later Von Anrep wrote an paper about it. Von Anrep wrote an paper about it. • Sigmund Freud and Karl Koller in 1884 used as Local Sigmund Freud and Karl Koller in 1884 used as Local Anaesthetic for the eye at an opthalmological congress Anaesthetic for the eye at an opthalmological congress • Leonard Corning –Text Book on Local Anesthesia Published in Leonard Corning –Text Book on Local Anesthesia Published in 1886 1886 • August Bier in 1898- Spinal Anesthesia(3ml of 0.5% Cocaine) August Bier in 1898- Spinal Anesthesia(3ml of 0.5% Cocaine) • Biers block in 1908 Biers block in 1908 • Caudal epidural Anesthesia in 1901 – Ferdinand Cathelin and Caudal epidural Anesthesia in 1901 – Ferdinand Cathelin and Jean Sicard Jean Sicard • Lumber epidural in 1921 – Fidel pages and again in 1931 by Lumber epidural in 1921 – Fidel pages and again in 1931 by Achillle Dogliotti Achillle Dogliotti
05/31/25 05/31/25 4 4 Pharmacology of local anesthetics Pharmacology of local anesthetics CHEMISTRY: CHEMISTRY: • The typical local anesthetic molecule is a tertiary The typical local anesthetic molecule is a tertiary amine attached to an aromatic system by an amine attached to an aromatic system by an intermediate chain. intermediate chain. • The tertiary amine is a Base ( Proton acceptor) The tertiary amine is a Base ( Proton acceptor) • The chain always contains either an ester or amide The chain always contains either an ester or amide linkage. linkage. • Thus classified ; Thus classified ; a) Amino esters a) Amino esters b) Amino amide b) Amino amide
05/31/25 05/31/25 5 5 Classification Classification 􀂾 Aminoamids: 􀂃 Lidocaine 􀂃 Prilocaine 􀂃 Mepivacaine 􀂃 Etidocaine 􀂃 Bupivacaine 􀂃 Ropivacaine 􀂃 Levobupivacaine 􀂾 Aminoesters: 􀂃 Cocaine 􀂃 Procaine 􀂃 Chloroprocaine 􀂃 Tetracaine 􀂾 Aromatic portion Intermediate chain Amine portion
05/31/25 05/31/25 6 6 Structure-Activity Relationships 1. Aromatic portion– Responsible for lipophilicity of compounds, i.e., lipid/water distribution and protein binding characteristics. 2. Amine portion– usually a secondary or tertiary amine and is associated with water solubility of the compounds, but is not necessary for anesthetic activity. Compounds lacking the amine portion are insoluble in water and useful only topically. 3. Intermediate linkage– connected to aromatic residue via an ester or amide linkage. Type of linkage important in determining the route of metabolism and the allergic potential of the compounds. 4. Other classes of compounds– not usually classified as local anesthetics, but share this same general structure and thus exhibit local anesthetic properties: • beta-blocking agents • antihistamines (e.g. diphenhydramine
05/31/25 05/31/25 7 7 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Classification Classification Esters Esters Cocaine Cocaine - - 1884 1884 Procaine Procaine - - 1905 1905 Tetracaine - 1932 Tetracaine - 1932 chloroprocaine - chloroprocaine - 1955 1955
05/31/25 05/31/25 8 8 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Classification Classification Amides Amides Lignocaine Lignocaine - - 1944 1944 Mepivacaine Mepivacaine - - 1957 1957 Prilocaine Prilocaine - - 1960 1960 Bupivacaine Bupivacaine - - 1963 1963 Etidocaine Etidocaine - - 1972 1972 Ropivacaine Ropivacaine - - 1990 1990
05/31/25 05/31/25 9 9 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Properties of an ideal Local anaesthetic agent Properties of an ideal Local anaesthetic agent 1. 1. Reversible action Reversible action 2. 2. Nonirritating to the tissues and produce no secondary local reaction Nonirritating to the tissues and produce no secondary local reaction 3. 3. Low degree of systematic toxicity Low degree of systematic toxicity 4. 4. Rapid onset and sufficient duration of action Rapid onset and sufficient duration of action 5. 5. Potency sufficient to give complete anaesthesia Potency sufficient to give complete anaesthesia 6. 6. Sufficient penetrating properties to be effective as a topical anaesthesia Sufficient penetrating properties to be effective as a topical anaesthesia 7. 7. Free from producing allergic reactions Free from producing allergic reactions 8. 8. Stable in solution and undergo biotransformation readily within the Stable in solution and undergo biotransformation readily within the body body 9. 9. Either sterile or capable of being sterilized by heat without Either sterile or capable of being sterilized by heat without deterioration deterioration No local anaesthetic agent in use today fulfills to perfection all No local anaesthetic agent in use today fulfills to perfection all these requirements these requirements. .
05/31/25 05/31/25 10 10 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Properties of commonly used local Properties of commonly used local anaesthetic agents anaesthetic agents 1. 1. Synthetic Synthetic 2. 2. Contain amino groups Contain amino groups 3. 3. Form salts with strong acids Form salts with strong acids 4. 4. The salts are water soluble The salts are water soluble 5. 5. Alkalies increases the concentration of the ionized Alkalies increases the concentration of the ionized free base free base 6. 6. The unionized free base is soluble in lipids The unionized free base is soluble in lipids 7. 7. The anaesthetic salts are acid in reaction and The anaesthetic salts are acid in reaction and relatively stable relatively stable
05/31/25 05/31/25 11 11 Properties of commonly used local Properties of commonly used local anaestheticagents (Contd.) anaestheticagents (Contd.) 8 8 Either hydrolyzed by plasma cholinesterase or Either hydrolyzed by plasma cholinesterase or undergo biotransformation in the liver undergo biotransformation in the liver 9 9 Action of all drugs are reversible Action of all drugs are reversible 10 10 Compatible with epinephrine Compatible with epinephrine 11 11 Incompatible with metal salts of mercury, silver, and Incompatible with metal salts of mercury, silver, and so forth so forth 12 12 Affect nerve conduction in a similar manner Affect nerve conduction in a similar manner 13 13 Produce toxic systemic effects when a sufficiently Produce toxic systemic effects when a sufficiently high plasma concentration is reached high plasma concentration is reached 14 14 They all have little or no irritating effect on tissues They all have little or no irritating effect on tissues in anaesthetic concentration in anaesthetic concentration
05/31/25 05/31/25 12 12 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Mechanism of Action: Mechanism of Action: Local anaesthetics prevent depolarization of the Local anaesthetics prevent depolarization of the nerve membrane by blocking sodium channels nerve membrane by blocking sodium channels and prevent conduction of impulses and prevent conduction of impulses Site of action Site of action *At the surface membrane of cells of *At the surface membrane of cells of excitable tissues excitable tissues *In a myelinated nerve - the node of *In a myelinated nerve - the node of Ranvier. Two or three adjacent nodes must be Ranvier. Two or three adjacent nodes must be affected to prevent conduction affected to prevent conduction *At least 6 - 10 mm of nerve fibre must be *At least 6 - 10 mm of nerve fibre must be exposed to the local anaesthetic agent or else a exposed to the local anaesthetic agent or else a blocked segment may be jumped. blocked segment may be jumped.
05/31/25 05/31/25 13 13 Effect of local anesthetics on nerve conduction: 􀂾 Local anesthetic and Na-channels: Reduced/blocked sodium entry Slower depolarisation Threshold level not reached Action potential not propagated
05/31/25 05/31/25 14 14 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Differential block Differential block *The minimum cocentration of local anaesthetic *The minimum cocentration of local anaesthetic necessary to cause block of a nerve fibre of given necessary to cause block of a nerve fibre of given diameter is known as the diameter is known as the Cm. Cm. *The thicker the diameter of a nerve the greater the Cm *The thicker the diameter of a nerve the greater the Cm required. required. *The A delta fibres have a Cm about half that of A alpha *The A delta fibres have a Cm about half that of A alpha fibres fibres *It is therefore possible to block pain sensation *It is therefore possible to block pain sensation while leaving sensation of pressure or position intact while leaving sensation of pressure or position intact *Sequence of block is autonomic – sensory – finally *Sequence of block is autonomic – sensory – finally motor according to fibre diameter motor according to fibre diameter
05/31/25 05/31/25 15 15 Sequence of clinical Anesthesia Sequence of clinical Anesthesia • Sympethetic block with peripheral vasodilation Sympethetic block with peripheral vasodilation and skin temp. elevation and skin temp. elevation • Loss of pain and temp sensation Loss of pain and temp sensation • Loss of proprioception Loss of proprioception • Loss of touch and pressure sensation Loss of touch and pressure sensation • Motor paralysis Motor paralysis pain > temperature > touch > pressure > skeletal muscle
05/31/25 05/31/25 16 16 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Local anaesthetics affect not only on nerve Local anaesthetics affect not only on nerve fibres but all types of excitable tisue, fibres but all types of excitable tisue, including smooth and striated muscle, e.g. in including smooth and striated muscle, e.g. in the myocardium ,vessels, probably by the myocardium ,vessels, probably by interfering with the cation fluxes across the interfering with the cation fluxes across the muscle-cell membranes muscle-cell membranes In moderate doses there is inhibition of In moderate doses there is inhibition of activity of ventricular ectopic foci in the heart. activity of ventricular ectopic foci in the heart.
05/31/25 05/31/25 17 17 B. Metabolism 1. Ester-type Local Anesthetics a. Hydrolyzed in plasma by pseudocholinesterases to their respective aromatic acid and alcohol. b. Patients with atypical forms of pseudocholinesterase may experience prolonged effects and exaggerated toxicity. c. Type of metabolites formed also of clinical importance, i.e. allergic phenomena associated with ester-type anesthetics attributable to formation of p-aminobenzoic acid. 2. Amide-type Local Anesthetics: Metabolized primarily in the liver byCYP P450 C. Excretion: Kidney is the major excretory route for excretion of unchanged drug and metabolites.
05/31/25 05/31/25 18 18 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity Toxicity Influenced by Influenced by 1. 1. Quantity of solution Quantity of solution 2. 2. Concentration of drug Concentration of drug 3. 3. Presence or absence of adrenaline Presence or absence of adrenaline 4. 4. Vascularity of site of injection Vascularity of site of injection 5. 5. Rate of absorption of drug Rate of absorption of drug 6. 6. Rate of destruction of drug Rate of destruction of drug 7. 7. Hypersensetivity of patient Hypersensetivity of patient 8. 8. Age, physical status and weight of patient Age, physical status and weight of patient Systemic Toxicity Systemic Toxicity usually results from either Intravascular usually results from either Intravascular injection or Over doses injection or Over doses
05/31/25 05/31/25 19 19 Relationship Between Local Anesthetic Plasma Level and Route of Administration
05/31/25 05/31/25 20 20 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system
05/31/25 05/31/25 21 21 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system Light headedness Light headedness Anxiety Anxiety Nausea Visual – Difficulty in foccussing Nausea Visual – Difficulty in foccussing Auditory – Tinnitus Shivering Auditory – Tinnitus Shivering Muscular Twitching Depression Muscular Twitching Depression Drowsiness Central stimulation followed by Drowsiness Central stimulation followed by Disorientation Restlessness Disorientation Restlessness Hysterical behaviour Vertigo Hysterical behaviour Vertigo Tremmor Convulsions Tremmor Convulsions Respiratory depression leading to arrest Respiratory depression leading to arrest
05/31/25 05/31/25 22 22 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system Treatment Treatment 1. 1. Oxygen, Artificial Ventilation if needed. Oxygen, Artificial Ventilation if needed. 2. 2. IV thiopentone/Phenytoin just IV thiopentone/Phenytoin just sufficient to control convulsions sufficient to control convulsions 3. 3. IV Diazepam may be useful IV Diazepam may be useful
05/31/25 05/31/25 23 23 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system
05/31/25 05/31/25 24 24 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system 1. 1. Hypotension Hypotension 2. 2. Acute collapse – Primary cardiac failure Acute collapse – Primary cardiac failure 3. 3. Feeble pulse Feeble pulse 4. 4. Bradycardia Bradycardia 5. 5. Pallor Pallor 6. 6. Sweating Sweating
05/31/25 05/31/25 25 25 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system Treatment Treatment 1. 1. Elevate legs Elevate legs 2. 2. Oxygen Oxygen 3. 3. Rapid IV infusion Rapid IV infusion 4. 4. Raise BP with ionotropes Raise BP with ionotropes 5. 5. Cardiac massage (CPR) Cardiac massage (CPR) 6. 6. Defibrillation Defibrillation 7. 7. Ventricular Arrythmias- Bretyllium 7mg/kg Ventricular Arrythmias- Bretyllium 7mg/kg
05/31/25 05/31/25 26 26 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Respiratory system Respiratory system
05/31/25 05/31/25 27 27 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Respiratory system Respiratory system Respiratory depression, may progress Respiratory depression, may progress to apnea from medullary depression or to apnea from medullary depression or respiratory muscle paralysis. It may respiratory muscle paralysis. It may have delayed onset have delayed onset
05/31/25 05/31/25 28 28 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Allergic phenomena Allergic phenomena Easter Easter linked agents:- Metabolites- PABA linked agents:- Metabolites- PABA 1. 1. Bronchospasm Bronchospasm 2. 2. Urticaria Urticaria 3. 3. Angioneurotic oedema Angioneurotic oedema 4. 4. Contact dermatitis Contact dermatitis Amide Amide-linked agents -linked agents Extremely rare but has been reported Extremely rare but has been reported
05/31/25 05/31/25 29 29 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Allergic phenomena Allergic phenomena Management Management 1. 1. Adrenaline Adrenaline 2. 2. Hydrocortisone Hydrocortisone 3. 3. Oxygen – IPPV Oxygen – IPPV 4. 4. Colloid, I/V Fluids Colloid, I/V Fluids
05/31/25 05/31/25 30 30 Pharmacology of Local Anesthetis agents Pharmacology of Local Anesthetis agents Toxicity can be minimized by : Toxicity can be minimized by : • Aspiration before injection Aspiration before injection • Use of epinephrine-containing solution for test dose Use of epinephrine-containing solution for test dose • Use of small incremental volumes in establishing the Use of small incremental volumes in establishing the blocks. blocks. • Use of proper technique during IV regional Use of proper technique during IV regional anesthesia anesthesia
05/31/25 05/31/25 31 31 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Improving duration and quality of local analgesia with addition of ADJUVENTS: Improving duration and quality of local analgesia with addition of ADJUVENTS: Adrenaline: Adrenaline: - 1 in 200 000 ( 0.1 ml of 1:1000 epinephrine to 20 ml) - 1 in 200 000 ( 0.1 ml of 1:1000 epinephrine to 20 ml) - Maximum dose 10 micro gm/kg in paed or 200-250 micro gm in Adult - Maximum dose 10 micro gm/kg in paed or 200-250 micro gm in Adult - The most common clinical manifestation is transient tachycardia. - The most common clinical manifestation is transient tachycardia. - At higher doses and with an inadvertent intravascular injection, palpitations, - At higher doses and with an inadvertent intravascular injection, palpitations, diaphoresis, angina, tremors, nervousness, and hypertension can occur diaphoresis, angina, tremors, nervousness, and hypertension can occur - Epinephrine must be used with caution in patients taking propranolol - Epinephrine must be used with caution in patients taking propranolol because life-threatening reactions have been reported; these include because life-threatening reactions have been reported; these include hypertension, myocardial infarction, and stroke hypertension, myocardial infarction, and stroke
05/31/25 05/31/25 32 32 Adrenaline…… Adrenaline…… - Adrenaline is contraindicated in patients with - Adrenaline is contraindicated in patients with pheochromocytoma, hyperthyroidism, severe pheochromocytoma, hyperthyroidism, severe hypertension, or severe peripheral vascular hypertension, or severe peripheral vascular occlusive disease, unstable angina pectoris, occlusive disease, unstable angina pectoris, Cardiac dysarrythmia. Cardiac dysarrythmia. - Relative contraindications include - Relative contraindications include pregnancy and psychological instability; pregnancy and psychological instability; epinephrine can induce an acute psychotic epinephrine can induce an acute psychotic episode in predisposed patients episode in predisposed patients
05/31/25 05/31/25 33 33 Pharmacology of Local Anesthetics Pharmacology of Local Anesthetics • Phenylephrine: Phenylephrine: Have similar effect like adrenaline without any Have similar effect like adrenaline without any particular advantage. particular advantage.
05/31/25 05/31/25 34 34 Pharmacolgy of Local Anesthetics agents Pharmacolgy of Local Anesthetics agents • Sodium Bicarbonate Sodium Bicarbonate - Raises the PH and increases the - Raises the PH and increases the concentration of non ionized free base , thus concentration of non ionized free base , thus increases the rate of diffusion, and speeds the increases the rate of diffusion, and speeds the onset of neural blockade. onset of neural blockade. - 1 mL of sodium bicarbonate 8.4% is added to - 1 mL of sodium bicarbonate 8.4% is added to 10 mL of the anesthetic solution to neutralize 10 mL of the anesthetic solution to neutralize the solution the solution
05/31/25 05/31/25 35 35 Pharmacolgy of Local Anesthetic agents Pharmacolgy of Local Anesthetic agents • Hyluronidase: Hyluronidase: - - Hyaluronidase is a bovine-derived enzyme that Hyaluronidase is a bovine-derived enzyme that hydrolyzes hyaluronic acid in the connective tissue and hydrolyzes hyaluronic acid in the connective tissue and facilitates the diffusion of the anesthetic facilitates the diffusion of the anesthetic. . - Increase the spread of anesthesia, - Increase the spread of anesthesia, - Decreases the duration of action of the anesthetics - Decreases the duration of action of the anesthetics because it increases absorption. because it increases absorption. - The usual dilution is 150 U in 30 mL of anesthetic. - The usual dilution is 150 U in 30 mL of anesthetic. - A patient can have an allergy to hyaluronidase as it is a - A patient can have an allergy to hyaluronidase as it is a foreign protein, and its use is contraindicated in patients foreign protein, and its use is contraindicated in patients with a known allergy to bee stings. with a known allergy to bee stings. - In addition, hyaluronidase contains the preservative - In addition, hyaluronidase contains the preservative thimerosal, which is also known allergen thimerosal, which is also known allergen
05/31/25 05/31/25 36 36 Pharmacology of Local Anestheic agents Pharmacology of Local Anestheic agents • Carbonation of Anesthetic Solution Carbonation of Anesthetic Solution - Addition of CO2 to the solution - Addition of CO2 to the solution - CO2 passes into the nerve and decreases the Ph - CO2 passes into the nerve and decreases the Ph inside due to formation of carbonic acid inside due to formation of carbonic acid - - Increasing the amount of Ionized LA inside, blocking Increasing the amount of Ionized LA inside, blocking more channels. more channels.
05/31/25 05/31/25 37 37 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents • Methods of local anaesthesia Methods of local anaesthesia
05/31/25 05/31/25 38 38 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Pre anaesthetic Check-up: Pre anaesthetic Check-up: Premedication: Premedication: Adequate premedication is Adequate premedication is essential for successful local essential for successful local anaesthesia in major cases anaesthesia in major cases mainly in regional blocks. mainly in regional blocks.
05/31/25 05/31/25 39 39 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Techniques of local anaesthesia Techniques of local anaesthesia 1. 1. Topical application-Surface anesthesia: Topical application-Surface anesthesia: 2. 2. Infiltration Infiltration 3. 3. Field blocks Field blocks 4. 4. Nerve block Nerve block 5. 5. Intravenous local analgesia Intravenous local analgesia 6. 6. Central neural blockade Central neural blockade
05/31/25 05/31/25 40 40 Techniques of local Techniques of local anaesthesia anaesthesia • Topical application-Surface anesthesia Topical application-Surface anesthesia - As a spray, Ointment, Paint - As a spray, Ointment, Paint - Cocaine 1-4 % - Cocaine 1-4 % - Lignocaine 4% spray - Lignocaine 4% spray - Lignocaine jelly 2% ( Xylocaine) - Lignocaine jelly 2% ( Xylocaine) - EMLA cream - EMLA cream - Used as Blind nasal intubation, - Used as Blind nasal intubation, Laryngoscopy, Bronchoscopy, I/V line open in Laryngoscopy, Bronchoscopy, I/V line open in small childe, Catheterization, cystoscopy etc small childe, Catheterization, cystoscopy etc
05/31/25 05/31/25 41 41 Techniques of local Techniques of local anaesthesia anaesthesia • Infiltration: Infiltration: - Very simple, effective, require no extra - Very simple, effective, require no extra skill skill - Used in minor surgery, surface - Used in minor surgery, surface operation operation - very common outdoor practice - very common outdoor practice
05/31/25 05/31/25 42 42 Techniques of local Techniques of local anaesthesia anaesthesia • Field blocks: Field blocks: - Injecting the LA solution across the - Injecting the LA solution across the nerve pathway supplying the nerve nerve pathway supplying the nerve pathway. pathway. - Opn of Inguinal hernia, Hydrocoel - Opn of Inguinal hernia, Hydrocoel
05/31/25 05/31/25 43 43 Techniques of local Techniques of local anaesthesia anaesthesia • Nerve block: Nerve block: - Conduction Block - Conduction Block - Particular nerve or group of nerve are - Particular nerve or group of nerve are blocked blocked - Requires adequate skill and anatomical - Requires adequate skill and anatomical knowledge knowledge - Brachial plexus block, ankle block, - Brachial plexus block, ankle block, intercostal nerve block intercostal nerve block
05/31/25 05/31/25 44 44 Techniques of local Techniques of local anaesthesia anaesthesia • Intravenous local analgesia Intravenous local analgesia - Bier’s Block - Bier’s Block - Particular limb is made ischaemic by - Particular limb is made ischaemic by applying tourniquate, Large volume of applying tourniquate, Large volume of LA solution injected intravenously LA solution injected intravenously - up to 40 ml for upper limb and 80 ml - up to 40 ml for upper limb and 80 ml for lower limb for lower limb - Tourniquate failure leads sever toxicity - Tourniquate failure leads sever toxicity
05/31/25 05/31/25 45 45 Techniques of local Techniques of local anaesthesia anaesthesia 1. 1. Central neural blockade Central neural blockade - Sub arachnoid block - Sub arachnoid block - Epidural Block - Epidural Block - Caudal block - Caudal block
05/31/25 05/31/25 46 46 Advantage of Local Anesthesia Advantage of Local Anesthesia • Early ambulation Early ambulation • Early oral feeding Early oral feeding • Patient is conscious, respiratory and CVS Patient is conscious, respiratory and CVS system are mostly unaffected system are mostly unaffected • Post general anesthetic complication like Post general anesthetic complication like PONV, Pain is less. PONV, Pain is less. • Operative bleeding is less Operative bleeding is less • Minimum equipment is needed Minimum equipment is needed • Cheap Cheap
05/31/25 05/31/25 47 47 Disadvantage Disadvantage • Perfect analgesia not guaranted Perfect analgesia not guaranted • General anesthesia may be needed, if General anesthesia may be needed, if LA is failed LA is failed • Patients might feel discomfort due to Patients might feel discomfort due to consciousness consciousness • unsuitable for infant, children and unsuitable for infant, children and uncooperative patients uncooperative patients • Local infection, Lengthy operation Local infection, Lengthy operation
05/31/25 05/31/25 48 48 Monitored Anesthetic Care ( MAC) Monitored Anesthetic Care ( MAC) • Anesthesiologist as an Monitor. Anesthesiologist as an Monitor. • Anesthesiologist Standby during a procedure Anesthesiologist Standby during a procedure performed with intravenous sedation or LA performed with intravenous sedation or LA administered by the surgeon. administered by the surgeon. • Complication early noticed and managed Complication early noticed and managed accordingly. accordingly. • All necessary equipment and Drugs should be All necessary equipment and Drugs should be in hand. in hand.
05/31/25 05/31/25 49 49 SAQ SAQ • Define Local Anesthesia. What determine Define Local Anesthesia. What determine the onset time of action, duration of the onset time of action, duration of action, and potency of Local Anesthetics? action, and potency of Local Anesthetics? • Briefly describe the Local Anesthetic Briefly describe the Local Anesthetic toxicity and its management. toxicity and its management. • Describe in short about monitored Describe in short about monitored anesthetic care. anesthetic care.
05/31/25 05/31/25 50 50 MCQ MCQ • Amide type of Anesthetic should be Amide type of Anesthetic should be used with great caution in Pts of used with great caution in Pts of a) a) Severe Liver Disease Severe Liver Disease b) b) Severe Kidney disease Severe Kidney disease c) c) Severe Respiratory disease Severe Respiratory disease d) d) Cardiac disease Cardiac disease
05/31/25 05/31/25 51 51 MCQ MCQ • PABA ( Para amino benzoic acid ) is an PABA ( Para amino benzoic acid ) is an allergic metabolic products of : allergic metabolic products of : a) Prilocaine a) Prilocaine b) Lidocaine b) Lidocaine c) Procaine c) Procaine d) Etidocaine d) Etidocaine
05/31/25 05/31/25 52 52 MCQ MCQ • To enhance chemical stability, To enhance chemical stability, commercial preparation of local commercial preparation of local anesthetic drugs are supplied in anesthetic drugs are supplied in a) a) Acidic PH Acidic PH b) b) Alkaline PH Alkaline PH c) c) Neutral PH Neutral PH d) d) Acidic and Alkaline PH depending upon Acidic and Alkaline PH depending upon the addition of vasoconstrictor agent the addition of vasoconstrictor agent
05/31/25 05/31/25 53 53 MCQ MCQ • Which one is the oldest first Local Which one is the oldest first Local Anesthetic agent Anesthetic agent a) a) Cocaine Cocaine b) b) Procain Procain c) c) Lidocaine Lidocaine d) d) Chloroprocaine Chloroprocaine
05/31/25 05/31/25 54 54 THANK YOU ALL THANK YOU ALL

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1st yr Class for Local Anesthesia - 1- NKC.ppt

  • 1. Pharmacology of Local anaesthetic Pharmacology of Local anaesthetic agents agents
  • 2. 05/31/25 05/31/25 2 2 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents • A Local Anaesthetic Agent reversibly blocks A Local Anaesthetic Agent reversibly blocks nerve conduction beyond the point of application, nerve conduction beyond the point of application, when applied locally in the appropriate concentration. when applied locally in the appropriate concentration. • Drugs that produce transient and reversible loss of sensation or feeling in a circumscribed area of the body without loss of consciousness. • Safer than General Anesthesia Safer than General Anesthesia • Widely used Widely used
  • 3. 05/31/25 05/31/25 3 3 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents History History • Cocaine Cocaine-Mid 19 -Mid 19th th century in Europe and America receive century in Europe and America receive attention, Around 1860 Albert Niemann isolated and 20 yrs later attention, Around 1860 Albert Niemann isolated and 20 yrs later Von Anrep wrote an paper about it. Von Anrep wrote an paper about it. • Sigmund Freud and Karl Koller in 1884 used as Local Sigmund Freud and Karl Koller in 1884 used as Local Anaesthetic for the eye at an opthalmological congress Anaesthetic for the eye at an opthalmological congress • Leonard Corning –Text Book on Local Anesthesia Published in Leonard Corning –Text Book on Local Anesthesia Published in 1886 1886 • August Bier in 1898- Spinal Anesthesia(3ml of 0.5% Cocaine) August Bier in 1898- Spinal Anesthesia(3ml of 0.5% Cocaine) • Biers block in 1908 Biers block in 1908 • Caudal epidural Anesthesia in 1901 – Ferdinand Cathelin and Caudal epidural Anesthesia in 1901 – Ferdinand Cathelin and Jean Sicard Jean Sicard • Lumber epidural in 1921 – Fidel pages and again in 1931 by Lumber epidural in 1921 – Fidel pages and again in 1931 by Achillle Dogliotti Achillle Dogliotti
  • 4. 05/31/25 05/31/25 4 4 Pharmacology of local anesthetics Pharmacology of local anesthetics CHEMISTRY: CHEMISTRY: • The typical local anesthetic molecule is a tertiary The typical local anesthetic molecule is a tertiary amine attached to an aromatic system by an amine attached to an aromatic system by an intermediate chain. intermediate chain. • The tertiary amine is a Base ( Proton acceptor) The tertiary amine is a Base ( Proton acceptor) • The chain always contains either an ester or amide The chain always contains either an ester or amide linkage. linkage. • Thus classified ; Thus classified ; a) Amino esters a) Amino esters b) Amino amide b) Amino amide
  • 5. 05/31/25 05/31/25 5 5 Classification Classification 􀂾 Aminoamids: 􀂃 Lidocaine 􀂃 Prilocaine 􀂃 Mepivacaine 􀂃 Etidocaine 􀂃 Bupivacaine 􀂃 Ropivacaine 􀂃 Levobupivacaine 􀂾 Aminoesters: 􀂃 Cocaine 􀂃 Procaine 􀂃 Chloroprocaine 􀂃 Tetracaine 􀂾 Aromatic portion Intermediate chain Amine portion
  • 6. 05/31/25 05/31/25 6 6 Structure-Activity Relationships 1. Aromatic portion– Responsible for lipophilicity of compounds, i.e., lipid/water distribution and protein binding characteristics. 2. Amine portion– usually a secondary or tertiary amine and is associated with water solubility of the compounds, but is not necessary for anesthetic activity. Compounds lacking the amine portion are insoluble in water and useful only topically. 3. Intermediate linkage– connected to aromatic residue via an ester or amide linkage. Type of linkage important in determining the route of metabolism and the allergic potential of the compounds. 4. Other classes of compounds– not usually classified as local anesthetics, but share this same general structure and thus exhibit local anesthetic properties: • beta-blocking agents • antihistamines (e.g. diphenhydramine
  • 7. 05/31/25 05/31/25 7 7 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Classification Classification Esters Esters Cocaine Cocaine - - 1884 1884 Procaine Procaine - - 1905 1905 Tetracaine - 1932 Tetracaine - 1932 chloroprocaine - chloroprocaine - 1955 1955
  • 8. 05/31/25 05/31/25 8 8 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Classification Classification Amides Amides Lignocaine Lignocaine - - 1944 1944 Mepivacaine Mepivacaine - - 1957 1957 Prilocaine Prilocaine - - 1960 1960 Bupivacaine Bupivacaine - - 1963 1963 Etidocaine Etidocaine - - 1972 1972 Ropivacaine Ropivacaine - - 1990 1990
  • 9. 05/31/25 05/31/25 9 9 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Properties of an ideal Local anaesthetic agent Properties of an ideal Local anaesthetic agent 1. 1. Reversible action Reversible action 2. 2. Nonirritating to the tissues and produce no secondary local reaction Nonirritating to the tissues and produce no secondary local reaction 3. 3. Low degree of systematic toxicity Low degree of systematic toxicity 4. 4. Rapid onset and sufficient duration of action Rapid onset and sufficient duration of action 5. 5. Potency sufficient to give complete anaesthesia Potency sufficient to give complete anaesthesia 6. 6. Sufficient penetrating properties to be effective as a topical anaesthesia Sufficient penetrating properties to be effective as a topical anaesthesia 7. 7. Free from producing allergic reactions Free from producing allergic reactions 8. 8. Stable in solution and undergo biotransformation readily within the Stable in solution and undergo biotransformation readily within the body body 9. 9. Either sterile or capable of being sterilized by heat without Either sterile or capable of being sterilized by heat without deterioration deterioration No local anaesthetic agent in use today fulfills to perfection all No local anaesthetic agent in use today fulfills to perfection all these requirements these requirements. .
  • 10. 05/31/25 05/31/25 10 10 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Properties of commonly used local Properties of commonly used local anaesthetic agents anaesthetic agents 1. 1. Synthetic Synthetic 2. 2. Contain amino groups Contain amino groups 3. 3. Form salts with strong acids Form salts with strong acids 4. 4. The salts are water soluble The salts are water soluble 5. 5. Alkalies increases the concentration of the ionized Alkalies increases the concentration of the ionized free base free base 6. 6. The unionized free base is soluble in lipids The unionized free base is soluble in lipids 7. 7. The anaesthetic salts are acid in reaction and The anaesthetic salts are acid in reaction and relatively stable relatively stable
  • 11. 05/31/25 05/31/25 11 11 Properties of commonly used local Properties of commonly used local anaestheticagents (Contd.) anaestheticagents (Contd.) 8 8 Either hydrolyzed by plasma cholinesterase or Either hydrolyzed by plasma cholinesterase or undergo biotransformation in the liver undergo biotransformation in the liver 9 9 Action of all drugs are reversible Action of all drugs are reversible 10 10 Compatible with epinephrine Compatible with epinephrine 11 11 Incompatible with metal salts of mercury, silver, and Incompatible with metal salts of mercury, silver, and so forth so forth 12 12 Affect nerve conduction in a similar manner Affect nerve conduction in a similar manner 13 13 Produce toxic systemic effects when a sufficiently Produce toxic systemic effects when a sufficiently high plasma concentration is reached high plasma concentration is reached 14 14 They all have little or no irritating effect on tissues They all have little or no irritating effect on tissues in anaesthetic concentration in anaesthetic concentration
  • 12. 05/31/25 05/31/25 12 12 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Mechanism of Action: Mechanism of Action: Local anaesthetics prevent depolarization of the Local anaesthetics prevent depolarization of the nerve membrane by blocking sodium channels nerve membrane by blocking sodium channels and prevent conduction of impulses and prevent conduction of impulses Site of action Site of action *At the surface membrane of cells of *At the surface membrane of cells of excitable tissues excitable tissues *In a myelinated nerve - the node of *In a myelinated nerve - the node of Ranvier. Two or three adjacent nodes must be Ranvier. Two or three adjacent nodes must be affected to prevent conduction affected to prevent conduction *At least 6 - 10 mm of nerve fibre must be *At least 6 - 10 mm of nerve fibre must be exposed to the local anaesthetic agent or else a exposed to the local anaesthetic agent or else a blocked segment may be jumped. blocked segment may be jumped.
  • 13. 05/31/25 05/31/25 13 13 Effect of local anesthetics on nerve conduction: 􀂾 Local anesthetic and Na-channels: Reduced/blocked sodium entry Slower depolarisation Threshold level not reached Action potential not propagated
  • 14. 05/31/25 05/31/25 14 14 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Differential block Differential block *The minimum cocentration of local anaesthetic *The minimum cocentration of local anaesthetic necessary to cause block of a nerve fibre of given necessary to cause block of a nerve fibre of given diameter is known as the diameter is known as the Cm. Cm. *The thicker the diameter of a nerve the greater the Cm *The thicker the diameter of a nerve the greater the Cm required. required. *The A delta fibres have a Cm about half that of A alpha *The A delta fibres have a Cm about half that of A alpha fibres fibres *It is therefore possible to block pain sensation *It is therefore possible to block pain sensation while leaving sensation of pressure or position intact while leaving sensation of pressure or position intact *Sequence of block is autonomic – sensory – finally *Sequence of block is autonomic – sensory – finally motor according to fibre diameter motor according to fibre diameter
  • 15. 05/31/25 05/31/25 15 15 Sequence of clinical Anesthesia Sequence of clinical Anesthesia • Sympethetic block with peripheral vasodilation Sympethetic block with peripheral vasodilation and skin temp. elevation and skin temp. elevation • Loss of pain and temp sensation Loss of pain and temp sensation • Loss of proprioception Loss of proprioception • Loss of touch and pressure sensation Loss of touch and pressure sensation • Motor paralysis Motor paralysis pain > temperature > touch > pressure > skeletal muscle
  • 16. 05/31/25 05/31/25 16 16 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Local anaesthetics affect not only on nerve Local anaesthetics affect not only on nerve fibres but all types of excitable tisue, fibres but all types of excitable tisue, including smooth and striated muscle, e.g. in including smooth and striated muscle, e.g. in the myocardium ,vessels, probably by the myocardium ,vessels, probably by interfering with the cation fluxes across the interfering with the cation fluxes across the muscle-cell membranes muscle-cell membranes In moderate doses there is inhibition of In moderate doses there is inhibition of activity of ventricular ectopic foci in the heart. activity of ventricular ectopic foci in the heart.
  • 17. 05/31/25 05/31/25 17 17 B. Metabolism 1. Ester-type Local Anesthetics a. Hydrolyzed in plasma by pseudocholinesterases to their respective aromatic acid and alcohol. b. Patients with atypical forms of pseudocholinesterase may experience prolonged effects and exaggerated toxicity. c. Type of metabolites formed also of clinical importance, i.e. allergic phenomena associated with ester-type anesthetics attributable to formation of p-aminobenzoic acid. 2. Amide-type Local Anesthetics: Metabolized primarily in the liver byCYP P450 C. Excretion: Kidney is the major excretory route for excretion of unchanged drug and metabolites.
  • 18. 05/31/25 05/31/25 18 18 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity Toxicity Influenced by Influenced by 1. 1. Quantity of solution Quantity of solution 2. 2. Concentration of drug Concentration of drug 3. 3. Presence or absence of adrenaline Presence or absence of adrenaline 4. 4. Vascularity of site of injection Vascularity of site of injection 5. 5. Rate of absorption of drug Rate of absorption of drug 6. 6. Rate of destruction of drug Rate of destruction of drug 7. 7. Hypersensetivity of patient Hypersensetivity of patient 8. 8. Age, physical status and weight of patient Age, physical status and weight of patient Systemic Toxicity Systemic Toxicity usually results from either Intravascular usually results from either Intravascular injection or Over doses injection or Over doses
  • 19. 05/31/25 05/31/25 19 19 Relationship Between Local Anesthetic Plasma Level and Route of Administration
  • 20. 05/31/25 05/31/25 20 20 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system
  • 21. 05/31/25 05/31/25 21 21 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system Light headedness Light headedness Anxiety Anxiety Nausea Visual – Difficulty in foccussing Nausea Visual – Difficulty in foccussing Auditory – Tinnitus Shivering Auditory – Tinnitus Shivering Muscular Twitching Depression Muscular Twitching Depression Drowsiness Central stimulation followed by Drowsiness Central stimulation followed by Disorientation Restlessness Disorientation Restlessness Hysterical behaviour Vertigo Hysterical behaviour Vertigo Tremmor Convulsions Tremmor Convulsions Respiratory depression leading to arrest Respiratory depression leading to arrest
  • 22. 05/31/25 05/31/25 22 22 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Central Nervous system Central Nervous system Treatment Treatment 1. 1. Oxygen, Artificial Ventilation if needed. Oxygen, Artificial Ventilation if needed. 2. 2. IV thiopentone/Phenytoin just IV thiopentone/Phenytoin just sufficient to control convulsions sufficient to control convulsions 3. 3. IV Diazepam may be useful IV Diazepam may be useful
  • 23. 05/31/25 05/31/25 23 23 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system
  • 24. 05/31/25 05/31/25 24 24 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system 1. 1. Hypotension Hypotension 2. 2. Acute collapse – Primary cardiac failure Acute collapse – Primary cardiac failure 3. 3. Feeble pulse Feeble pulse 4. 4. Bradycardia Bradycardia 5. 5. Pallor Pallor 6. 6. Sweating Sweating
  • 25. 05/31/25 05/31/25 25 25 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Cardiovascular system Cardiovascular system Treatment Treatment 1. 1. Elevate legs Elevate legs 2. 2. Oxygen Oxygen 3. 3. Rapid IV infusion Rapid IV infusion 4. 4. Raise BP with ionotropes Raise BP with ionotropes 5. 5. Cardiac massage (CPR) Cardiac massage (CPR) 6. 6. Defibrillation Defibrillation 7. 7. Ventricular Arrythmias- Bretyllium 7mg/kg Ventricular Arrythmias- Bretyllium 7mg/kg
  • 26. 05/31/25 05/31/25 26 26 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Respiratory system Respiratory system
  • 27. 05/31/25 05/31/25 27 27 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Respiratory system Respiratory system Respiratory depression, may progress Respiratory depression, may progress to apnea from medullary depression or to apnea from medullary depression or respiratory muscle paralysis. It may respiratory muscle paralysis. It may have delayed onset have delayed onset
  • 28. 05/31/25 05/31/25 28 28 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Allergic phenomena Allergic phenomena Easter Easter linked agents:- Metabolites- PABA linked agents:- Metabolites- PABA 1. 1. Bronchospasm Bronchospasm 2. 2. Urticaria Urticaria 3. 3. Angioneurotic oedema Angioneurotic oedema 4. 4. Contact dermatitis Contact dermatitis Amide Amide-linked agents -linked agents Extremely rare but has been reported Extremely rare but has been reported
  • 29. 05/31/25 05/31/25 29 29 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Toxicity contd Toxicity contd. . Allergic phenomena Allergic phenomena Management Management 1. 1. Adrenaline Adrenaline 2. 2. Hydrocortisone Hydrocortisone 3. 3. Oxygen – IPPV Oxygen – IPPV 4. 4. Colloid, I/V Fluids Colloid, I/V Fluids
  • 30. 05/31/25 05/31/25 30 30 Pharmacology of Local Anesthetis agents Pharmacology of Local Anesthetis agents Toxicity can be minimized by : Toxicity can be minimized by : • Aspiration before injection Aspiration before injection • Use of epinephrine-containing solution for test dose Use of epinephrine-containing solution for test dose • Use of small incremental volumes in establishing the Use of small incremental volumes in establishing the blocks. blocks. • Use of proper technique during IV regional Use of proper technique during IV regional anesthesia anesthesia
  • 31. 05/31/25 05/31/25 31 31 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Improving duration and quality of local analgesia with addition of ADJUVENTS: Improving duration and quality of local analgesia with addition of ADJUVENTS: Adrenaline: Adrenaline: - 1 in 200 000 ( 0.1 ml of 1:1000 epinephrine to 20 ml) - 1 in 200 000 ( 0.1 ml of 1:1000 epinephrine to 20 ml) - Maximum dose 10 micro gm/kg in paed or 200-250 micro gm in Adult - Maximum dose 10 micro gm/kg in paed or 200-250 micro gm in Adult - The most common clinical manifestation is transient tachycardia. - The most common clinical manifestation is transient tachycardia. - At higher doses and with an inadvertent intravascular injection, palpitations, - At higher doses and with an inadvertent intravascular injection, palpitations, diaphoresis, angina, tremors, nervousness, and hypertension can occur diaphoresis, angina, tremors, nervousness, and hypertension can occur - Epinephrine must be used with caution in patients taking propranolol - Epinephrine must be used with caution in patients taking propranolol because life-threatening reactions have been reported; these include because life-threatening reactions have been reported; these include hypertension, myocardial infarction, and stroke hypertension, myocardial infarction, and stroke
  • 32. 05/31/25 05/31/25 32 32 Adrenaline…… Adrenaline…… - Adrenaline is contraindicated in patients with - Adrenaline is contraindicated in patients with pheochromocytoma, hyperthyroidism, severe pheochromocytoma, hyperthyroidism, severe hypertension, or severe peripheral vascular hypertension, or severe peripheral vascular occlusive disease, unstable angina pectoris, occlusive disease, unstable angina pectoris, Cardiac dysarrythmia. Cardiac dysarrythmia. - Relative contraindications include - Relative contraindications include pregnancy and psychological instability; pregnancy and psychological instability; epinephrine can induce an acute psychotic epinephrine can induce an acute psychotic episode in predisposed patients episode in predisposed patients
  • 33. 05/31/25 05/31/25 33 33 Pharmacology of Local Anesthetics Pharmacology of Local Anesthetics • Phenylephrine: Phenylephrine: Have similar effect like adrenaline without any Have similar effect like adrenaline without any particular advantage. particular advantage.
  • 34. 05/31/25 05/31/25 34 34 Pharmacolgy of Local Anesthetics agents Pharmacolgy of Local Anesthetics agents • Sodium Bicarbonate Sodium Bicarbonate - Raises the PH and increases the - Raises the PH and increases the concentration of non ionized free base , thus concentration of non ionized free base , thus increases the rate of diffusion, and speeds the increases the rate of diffusion, and speeds the onset of neural blockade. onset of neural blockade. - 1 mL of sodium bicarbonate 8.4% is added to - 1 mL of sodium bicarbonate 8.4% is added to 10 mL of the anesthetic solution to neutralize 10 mL of the anesthetic solution to neutralize the solution the solution
  • 35. 05/31/25 05/31/25 35 35 Pharmacolgy of Local Anesthetic agents Pharmacolgy of Local Anesthetic agents • Hyluronidase: Hyluronidase: - - Hyaluronidase is a bovine-derived enzyme that Hyaluronidase is a bovine-derived enzyme that hydrolyzes hyaluronic acid in the connective tissue and hydrolyzes hyaluronic acid in the connective tissue and facilitates the diffusion of the anesthetic facilitates the diffusion of the anesthetic. . - Increase the spread of anesthesia, - Increase the spread of anesthesia, - Decreases the duration of action of the anesthetics - Decreases the duration of action of the anesthetics because it increases absorption. because it increases absorption. - The usual dilution is 150 U in 30 mL of anesthetic. - The usual dilution is 150 U in 30 mL of anesthetic. - A patient can have an allergy to hyaluronidase as it is a - A patient can have an allergy to hyaluronidase as it is a foreign protein, and its use is contraindicated in patients foreign protein, and its use is contraindicated in patients with a known allergy to bee stings. with a known allergy to bee stings. - In addition, hyaluronidase contains the preservative - In addition, hyaluronidase contains the preservative thimerosal, which is also known allergen thimerosal, which is also known allergen
  • 36. 05/31/25 05/31/25 36 36 Pharmacology of Local Anestheic agents Pharmacology of Local Anestheic agents • Carbonation of Anesthetic Solution Carbonation of Anesthetic Solution - Addition of CO2 to the solution - Addition of CO2 to the solution - CO2 passes into the nerve and decreases the Ph - CO2 passes into the nerve and decreases the Ph inside due to formation of carbonic acid inside due to formation of carbonic acid - - Increasing the amount of Ionized LA inside, blocking Increasing the amount of Ionized LA inside, blocking more channels. more channels.
  • 37. 05/31/25 05/31/25 37 37 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents • Methods of local anaesthesia Methods of local anaesthesia
  • 38. 05/31/25 05/31/25 38 38 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Pre anaesthetic Check-up: Pre anaesthetic Check-up: Premedication: Premedication: Adequate premedication is Adequate premedication is essential for successful local essential for successful local anaesthesia in major cases anaesthesia in major cases mainly in regional blocks. mainly in regional blocks.
  • 39. 05/31/25 05/31/25 39 39 Pharmacology of Local anaesthetic agents Pharmacology of Local anaesthetic agents Techniques of local anaesthesia Techniques of local anaesthesia 1. 1. Topical application-Surface anesthesia: Topical application-Surface anesthesia: 2. 2. Infiltration Infiltration 3. 3. Field blocks Field blocks 4. 4. Nerve block Nerve block 5. 5. Intravenous local analgesia Intravenous local analgesia 6. 6. Central neural blockade Central neural blockade
  • 40. 05/31/25 05/31/25 40 40 Techniques of local Techniques of local anaesthesia anaesthesia • Topical application-Surface anesthesia Topical application-Surface anesthesia - As a spray, Ointment, Paint - As a spray, Ointment, Paint - Cocaine 1-4 % - Cocaine 1-4 % - Lignocaine 4% spray - Lignocaine 4% spray - Lignocaine jelly 2% ( Xylocaine) - Lignocaine jelly 2% ( Xylocaine) - EMLA cream - EMLA cream - Used as Blind nasal intubation, - Used as Blind nasal intubation, Laryngoscopy, Bronchoscopy, I/V line open in Laryngoscopy, Bronchoscopy, I/V line open in small childe, Catheterization, cystoscopy etc small childe, Catheterization, cystoscopy etc
  • 41. 05/31/25 05/31/25 41 41 Techniques of local Techniques of local anaesthesia anaesthesia • Infiltration: Infiltration: - Very simple, effective, require no extra - Very simple, effective, require no extra skill skill - Used in minor surgery, surface - Used in minor surgery, surface operation operation - very common outdoor practice - very common outdoor practice
  • 42. 05/31/25 05/31/25 42 42 Techniques of local Techniques of local anaesthesia anaesthesia • Field blocks: Field blocks: - Injecting the LA solution across the - Injecting the LA solution across the nerve pathway supplying the nerve nerve pathway supplying the nerve pathway. pathway. - Opn of Inguinal hernia, Hydrocoel - Opn of Inguinal hernia, Hydrocoel
  • 43. 05/31/25 05/31/25 43 43 Techniques of local Techniques of local anaesthesia anaesthesia • Nerve block: Nerve block: - Conduction Block - Conduction Block - Particular nerve or group of nerve are - Particular nerve or group of nerve are blocked blocked - Requires adequate skill and anatomical - Requires adequate skill and anatomical knowledge knowledge - Brachial plexus block, ankle block, - Brachial plexus block, ankle block, intercostal nerve block intercostal nerve block
  • 44. 05/31/25 05/31/25 44 44 Techniques of local Techniques of local anaesthesia anaesthesia • Intravenous local analgesia Intravenous local analgesia - Bier’s Block - Bier’s Block - Particular limb is made ischaemic by - Particular limb is made ischaemic by applying tourniquate, Large volume of applying tourniquate, Large volume of LA solution injected intravenously LA solution injected intravenously - up to 40 ml for upper limb and 80 ml - up to 40 ml for upper limb and 80 ml for lower limb for lower limb - Tourniquate failure leads sever toxicity - Tourniquate failure leads sever toxicity
  • 45. 05/31/25 05/31/25 45 45 Techniques of local Techniques of local anaesthesia anaesthesia 1. 1. Central neural blockade Central neural blockade - Sub arachnoid block - Sub arachnoid block - Epidural Block - Epidural Block - Caudal block - Caudal block
  • 46. 05/31/25 05/31/25 46 46 Advantage of Local Anesthesia Advantage of Local Anesthesia • Early ambulation Early ambulation • Early oral feeding Early oral feeding • Patient is conscious, respiratory and CVS Patient is conscious, respiratory and CVS system are mostly unaffected system are mostly unaffected • Post general anesthetic complication like Post general anesthetic complication like PONV, Pain is less. PONV, Pain is less. • Operative bleeding is less Operative bleeding is less • Minimum equipment is needed Minimum equipment is needed • Cheap Cheap
  • 47. 05/31/25 05/31/25 47 47 Disadvantage Disadvantage • Perfect analgesia not guaranted Perfect analgesia not guaranted • General anesthesia may be needed, if General anesthesia may be needed, if LA is failed LA is failed • Patients might feel discomfort due to Patients might feel discomfort due to consciousness consciousness • unsuitable for infant, children and unsuitable for infant, children and uncooperative patients uncooperative patients • Local infection, Lengthy operation Local infection, Lengthy operation
  • 48. 05/31/25 05/31/25 48 48 Monitored Anesthetic Care ( MAC) Monitored Anesthetic Care ( MAC) • Anesthesiologist as an Monitor. Anesthesiologist as an Monitor. • Anesthesiologist Standby during a procedure Anesthesiologist Standby during a procedure performed with intravenous sedation or LA performed with intravenous sedation or LA administered by the surgeon. administered by the surgeon. • Complication early noticed and managed Complication early noticed and managed accordingly. accordingly. • All necessary equipment and Drugs should be All necessary equipment and Drugs should be in hand. in hand.
  • 49. 05/31/25 05/31/25 49 49 SAQ SAQ • Define Local Anesthesia. What determine Define Local Anesthesia. What determine the onset time of action, duration of the onset time of action, duration of action, and potency of Local Anesthetics? action, and potency of Local Anesthetics? • Briefly describe the Local Anesthetic Briefly describe the Local Anesthetic toxicity and its management. toxicity and its management. • Describe in short about monitored Describe in short about monitored anesthetic care. anesthetic care.
  • 50. 05/31/25 05/31/25 50 50 MCQ MCQ • Amide type of Anesthetic should be Amide type of Anesthetic should be used with great caution in Pts of used with great caution in Pts of a) a) Severe Liver Disease Severe Liver Disease b) b) Severe Kidney disease Severe Kidney disease c) c) Severe Respiratory disease Severe Respiratory disease d) d) Cardiac disease Cardiac disease
  • 51. 05/31/25 05/31/25 51 51 MCQ MCQ • PABA ( Para amino benzoic acid ) is an PABA ( Para amino benzoic acid ) is an allergic metabolic products of : allergic metabolic products of : a) Prilocaine a) Prilocaine b) Lidocaine b) Lidocaine c) Procaine c) Procaine d) Etidocaine d) Etidocaine
  • 52. 05/31/25 05/31/25 52 52 MCQ MCQ • To enhance chemical stability, To enhance chemical stability, commercial preparation of local commercial preparation of local anesthetic drugs are supplied in anesthetic drugs are supplied in a) a) Acidic PH Acidic PH b) b) Alkaline PH Alkaline PH c) c) Neutral PH Neutral PH d) d) Acidic and Alkaline PH depending upon Acidic and Alkaline PH depending upon the addition of vasoconstrictor agent the addition of vasoconstrictor agent
  • 53. 05/31/25 05/31/25 53 53 MCQ MCQ • Which one is the oldest first Local Which one is the oldest first Local Anesthetic agent Anesthetic agent a) a) Cocaine Cocaine b) b) Procain Procain c) c) Lidocaine Lidocaine d) d) Chloroprocaine Chloroprocaine