【基础医学】第14章 局部麻醉药.pptVIP

Chapter 14 局部麻醉药 Local anesthetics Teaching goals (教学目标) 1、简述局麻原理及局麻方式 2、比较常用局麻药特点 * Definition （定义） Local anesthetics (LAs) are drugs that block both the generation(产生) and the conduction （传导）of the nerve impulse（冲动） when applied locally to nerve tissue in appropriate （适当的）concentrations. Local anesthetics produce the reversible（可逆的）loss of sensation without the loss of consciousness. * The first local anesthetic to be discovered was cocaine (可卡因). Owing to its addiction(成瘾), its clinical use was limited. A chemical search for synthetic(合成的) substitutes(代用品) for cocaine started in 1892. This resulted in 1905 in the synthesis of procaine(普鲁卡因), which is still useful local anesthetic. * 【structure - activity relationship】(构效关系) The molecule（分子） of LA can be divided into three main portions(部分): 芳香族环：疏水性(hydrophobicity)（亲脂性） 中间链： 酯：procaine 酰胺：lidocaine 烷基胺：亲水性(hydrophilism) （与H+结合后） * 【mechanism of local anesthesia】 LAs block action potential generation by blocking voltage – gated Na+ channels. LA在细胞内侧阻断电压门控性钠通道→阻断动作电位的产生和传导。 * 4、 subarachnoid anesthesia（蛛网膜下腔麻醉） spinal anesthesia (脊髓麻醉)或腰麻：脊N根 注意药液比重及病人的姿势。 5、 epidural anesthesia（硬膜外麻醉）：N根 【techniques of local anesthesia】(局麻方式) 1、 surface anesthesia（表面麻醉）：N末梢 2、 infiltration anesthesia（浸润麻醉）：N末梢 3、 conduction anesthesia（传导麻醉）：N干 * 【individuals of LAs】(常用药物) Procaine(普鲁卡因): 穿透力差，不用于表面麻醉。 It penetrates(透过) mucous membranes too poorly, so it can not be used for surface anesthesia. Lidocaine(利多卡因): 用于：1）各种局麻方式 ; 2）抗心律失常 It has a variety of clinical uses as a local anesthetic. In addition, it is used as an antiarrhythmic(抗心律失常的) agent. * Tetracaine (丁卡因) , ( 地卡因，dicaine)： It is too toxic to be used for filtration anesthesia. 【adverse reactions】 1. Absorption（吸收作用） CNS: 先（+）后（-） （+）：restlessness(不安), tremor(震颤),