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Local anesthetics PowerPoint Presentation

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This medical PowerPoint presentation talks about local anesthetics. Local anesthetics are drugs that produce temporary loss of sensation and pain in a specific area of the body without affecting consciousness. They work by blocking the transmission of nerve impulses from the site of application to the brain. Local anesthetics are commonly used in various medical and dental procedures, as well as in some cosmetic treatments.

There are two main types of local anesthetics: ester-type and amide-type. Ester-type local anesthetics, such as procaine and cocaine, are metabolized by plasma esterases and have a shorter duration of action. Amide-type local anesthetics, such as lidocaine and bupivacaine, are metabolized in the liver and have a longer duration of action.

Local anesthetics can be administered topically, as creams or gels applied to the skin or mucous membranes, or by injection directly into the affected area. They can also be given as a regional block, where the drug is injected near a cluster of nerves to numb a larger area of the body, such as an entire limb.

Tags : Local anesthetics, Ester-type local anesthetics, Amide-type local anesthetics, Anesthesiology

Published on : Mar 16, 2023 | Views : 633 | Downloads : 5

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Slide 1-

Local anesthetics
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Objectives Recall how an action potential is generated and propagated Classify local anesthtics Describe the machanism of action, pharmacokinetics and toxic effects of local anesthetics Describe the different techniqes of use of LA Describe the risks and benefits of using vasoconstrictors with LA
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Overview Local anesthetics produce a transient and reversible loss of sensation (analgesia) in a circumscribed region of the body without loss of consciousness. Normally, the process is completely reversible.
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ANESTHETICS
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Local anesthetics - esters or amides a lipophilic aromatic group to a hydrophilic, ionizable amine. Most are weak bases
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Classification of LA Esters Benzocaine Procaine/ Proparacaine
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Classification of LA Amide Bupivacaine Levobupivacaine Lidocaine/Lignocaine Mepivacaine
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Ionized
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Local anesthetics gain access to the inner axonal membrane by traversing sodium channels while they are more often in an open configuration passage directly through the plasma membrane
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Block inititation and propagation of action potential
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Sympathetic block (vasodilatation) Loss of pain and temperature sensation Loss of proprioception Loss of touch and pressure sensation Loss of motor function Sequence of clinical anesthesia
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Potency = lipid solubility Higher solubility = can use a lower concentration and reduce potential for toxicity Anesthetic Potency
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DURATION OF ACTION Duration = protein binding Bupivacaine 95%Lidocaine 65%
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Pharmacokinetics Effective within 5 min Duration of action – 1-1.5 h Activity is Ph dependent Increased action in acidic ph
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CLEARANCE ESTERShydrolysis via cholinesterase AMIDESmetabolism via hepatic enzymes
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LA Infiltration anesthesia Regional anesthesia Surface anesthesia
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LA Infiltration anesthesia Regional anesthesia Surface anesthesia
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Gegional anaesthesia Nerve block Intravenous Extradural Intrathecal block/ spinal anaesthesia
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Nerve block Inject a drug around the nerve Anaesthetise a region
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Intravenous 0.5-1% lidocaine without adrenaline
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Extradural/epidural Thoracic, lumbar, sacral Act on nerve roots No hypotention
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Spinal anesthesia Sympathetic nerve block hypotension
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LA Infiltration anesthesia Regional anesthesia Surface anesthesia
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On intact skin – eutectic mixture of bases of prilocaine (EMLA) Slow absorption
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Prolongation of action Add vasoconstrictor – adrenaline Can use a larger dose Not to – fingers, toes, nose, penis
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Adverse effects LA’s cause some vasodilatation at site LA toxicity related to rate of absorption via blood flow
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Systemic Toxicity Blockage of voltaged-gated Na channel affects action potential propagation throughout the body Potential is present for systemic toxicity
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Effects of local anesthetics Excitation – anxiety, agitation, restlessness Convulsions Reduced myocardial contractility Vasodilatation