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Chapter 7 Cholinoceptor-Blocking Drugs ( Ⅱ ) -N - Cholinoceptor blockers. Zhang bin Institute of Pharmacology School of Medicine Shandong University. Nicotinic cholinoceptor- blocking drugs. N N -R antagonists (ganglionic blocking drugs) N M -R antagonists
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Chapter 7 Cholinoceptor-Blocking Drugs (Ⅱ) -N -Cholinoceptor blockers Zhang bin Institute of Pharmacology School of Medicine Shandong University
Nicotinic cholinoceptor- blocking drugs NN-R antagonists (ganglionic blocking drugs) NM-R antagonists (neuromuscular blocking drugs ) (Skeletal muscle relaxants)
Section1 NN-R antagonists (ganglionic blocking drugs) Mecamylamine(美卡拉明,美加明) Trimethaphan(樟磺咪酚,曲美芬)
NN-R antagonists [Characteristics] Co-innervation and dominant theory • Blood vessel: vasodilation, peripheral resistance decrease, blood pressure decrease. • Glands, eye, GI, bladder: dry mouth, mydriasis, constipation, urinary retention [Clinical use]HBP
Section2NM-R antagonists (Skeletal muscle relaxants) (neuromuscular blocking drugs ) • Depolarizing skeletal muscle relaxants ——succinylcholine • Nondepolarizing skeletal muscle relaxants ——D-tubocurarine
Mechanism: Two-phase blockPhase 1: durable depolarizing blockPhase 2: NM receptor desensitization
Depolarizing skeletal muscle relaxants [Characteristics of Action] (1)Muscle fasciculation (肌束震颤) (2)Tachyphylaxis (快速耐受性) (3)Can’t be antagonized by AChEI (4)have no ganglionic blocking actions at therapeutic dose (5) rapid onset and short duration
succinylcholine (琥珀胆碱,scoline,司可林) (1)Onset rapid(1’), Emax 2’, short duration(5’) (2) Neck and limbs (3)pseudocholinesterase [Uses] 1.assistant agents of anesthetics 2.bronchial cannulation,bronchoscopy oesophagoscop(食道镜)
Adverse reactions (1) asphyxy(窒息): respiratory muscle paralysis: • genetic pseudo-ChE low patients • anti-AChE agents • local anesthetics and aminoglycosides (2) Muscle fasciculation (3) Elevation of extracellular K+ (4) CVS: complex (5) Malignant hyperpyrexia(恶性高热): idiosyncrasy (特异质反应) (6) increase histamine release
Malignant hyperpyrexia • 在并用琥珀胆碱和强挥发性全麻药(氟烷、异氟烷)时引起的高代谢反应,体温极度升高。是一种常染色体显性遗传。(钙释放通道基因变异,骨骼肌对钙呈高反应性,引起剧烈的肌肉收缩、代谢提高) • 丹曲林钠(肌松剂):其主要作用部位是骨骼肌的肌浆网,通过抑制肌浆网释放钙离子而减弱肌肉收缩。
Nondepolarizing muscular relaxants(competitive neuromuscular blockers)
Mechanisms: NM-Rcompetitive antagonist
Characteristics of Action • (1) no fasciculation • (2) Antagonized by AChEI • (3) slow onset and long duration • (4) NN blockade at therapeutic dose
d-tubocurarine(筒箭毒碱) [[Actions] • muscle relaxant • block ganglionic • release histamine [Uses] assistant agents of anesthetics
Other drugs benzylisoquinolines (苄基异喹啉类) Atracurium (阿曲库铵) Doxacurium (多库铵) Mivacurium (米库铵) ammoniosteroids(类固醇胺类) Pancuronium (泮库铵) Pipecuronium (哌库铵) Rocuronium (罗库铵) Vecuronium (维库铵)