Relative Contraindication for hepatic liver disease Example Lidocaine topical

Relative contraindication for hepatic liver disease

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Relative Contraindication for hepatic (liver) disease Example: Lidocaine (topical or Injectable) Mepivacaine (injectable only) Prilocaine (topical or Injectable) Articaine (injectable only) Bupivacaine (injectable only) 70
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Ester Local Anesthetics Metabolized by blood plasma enzymes (cholinesterase) Relative contraindication for Atypical Plasma Cholinesterase Example: Benzocaine (topical only) Tetracaine (topical only) Note: Injectable Ester local anesthetics are NOT MANUFACTURED due to a high incidence of systemic reactions 71
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Terminology for Systemic Effects Near (Approaching) Overdose Not toxic Overdose Toxic Greater Overdose More Toxic 72
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Summary of Effects of Local Anesthetics (Plain) on Systems Near OD OD Greater OD Central Nervous - Cardiovascular - Peripheral Vascular - Respiratory - + --- - --- - --- - --- 73
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Local Anesthetics (Plain) Both Amides and Esters are excreted by kidneys Therefore, local anesthetics (Amides and Esters) are Relative Contraindications with Renal (Kidney) Disease 74
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Vasoconstrictors The effects of vasoconstrictors can be both local and systemic Vasoconstrictors modify (alter) the effects of the local anesthetic 75
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Vasoconstrictors Act on Adrenergic Receptors Alpha-1 Receptor Agonist: Contraction of smooth muscle of blood vessels (vaso-constriction) Beta-1 Receptor Agonist: Stimulation of heart (rate and strength of contractions) Beta-2 Receptor Agonist: Relaxation of smooth muscle of bronchioles (broncho-dilation – Therefore , effective to treat bronchospasms of acute asthma 76
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Vasoconstrictors with Local Anesthetics The pH of a local anesthetic is lowered (3.0-4.5 vs 4.5-6.5) with a vasoconstrictor (acidic) The preservative Sodium bisulfite also lowers the pH – the presence of a vasoconstrictor requires the preservative sodium bisulfite (anti- oxidant) to delay oxidation and extend shelf life to 18 months (vs 36 months for plain anesthetic) Also, oxidation of a local anesthetic with time and/or heat also lowers the pH) 77
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Epinephrine Can be synthetic OR natural (animals) In acidic salt form (HCl) – therefore, lowers pH of a local anesthetic Acts directly on adrenergic receptors (A-1, B-1, B-2): mimics adrenergic activity of the sympathetic nervous system Concentrations available: 1:100,000, 1:200,000, 1:50,000 - avoid 1:50,000 if CVS is compromised (1:50,000 also causes a greater ‘rebound’ effect) 78
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Epinephrine ‘Rebound’ Effect ‘Rebound’ Effect (Vasodilation): Increased localized blood flow beginning approximately 6 hours post-operatively Greatest rebound effect when Lidocaine with 1:50,000 epinephrine has been administered Less rebound effect when Lidocaine with 1:100,000 epinephrine has been administered Least rebound effect when Lidocaine with 1:200,000 epinephrine has been administered 79
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levonordefrin (Neo-Cobefrin) Synthetic catecholamine Used with 2% Mepivacaine Causes the same effects as epinephrine Only 15% (1/6th) as potent as epinephrine, therefore requires a higher concentration for a sufficient vasoconstricting effect – a 1:20,000 concentration of levonordefrin (Neo- Cobefrin) is physiologically equivalent to epinephrine 1:100,000 80
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