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Cholinoceptor Blocking Drugs

Cholinoceptor Blocking Drugs . Classification. Base on specific receptor affinities Antimuscarinic agents Antinicotinic agents( consist of ganglion-blockers and neuromuscular junction blockers). Atropine and its alkaloids. Atropine Anisodamine Acopolamine.

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Cholinoceptor Blocking Drugs

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  1. Cholinoceptor Blocking Drugs

  2. Classification • Base on specific receptor affinities • Antimuscarinic agents • Antinicotinic agents( consist of ganglion-blockers and neuromuscular junction blockers)

  3. Atropine and its alkaloids • Atropine • Anisodamine • Acopolamine

  4. chemistry and pharmacokinetics • Tertiary amine alkaloid esters of tropic acid • Well absorbed from the gut and across the conjunctival membrane • Widely distributed • Metabolism and excretion

  5. Pharmacological Effects • Glands • Sweat, salivary gland secretion are greatly reduced • Bronchial secretion decreased • Reduction in gastric secretion and total acid content, especially at doses greater than 1 mg

  6. Pharmacological Effects • Eye • Mydriasis • ocular pressure increase • cycloplegia

  7. 动眼神经的副交感神经支配 毛果芸香碱激动 瞳孔括约肌 M受体 缩瞳 阿托品阻断 占优 瞳孔开大肌 扩瞳 激动 去甲状腺素能神经支配 虹膜(包括瞳孔括约肌和瞳孔开大肌 ) 毛果芸香碱的缩瞳作用

  8. 睫状体上皮 细胞分泌 血管渗出 狭窄时眼内压增高,闭角型青光眼(急,慢型充血性青光眼) 房水 瞳孔 毛果芸香碱收缩瞳孔括约肌 前房角间隙 前房 缩瞳虹膜拉紧 间隙扩大,房水入循环 虹膜根部变薄 降低眼内压 变性或硬化时眼内压增高 开角性青光眼(慢性单纯性青光眼) 小梁网 收缩睫状肌 扩张小血管 毛果芸香碱 巩膜静脉窦 阿托品扩瞳,虹膜退向四周,前房角 间隙变窄,房水回流受阻,眼内压升高 血流 毛果芸香碱的降低眼内压作用

  9. 正常时晶体较扁平 受睫状肌控制 环状肌 辐射状肌 (瞳孔括约肌) (瞳孔开大肌) 睫状肌起点 去甲肾上腺素能 神经支配 对眼调节无重要意义 阿托品 动眼神经兴奋或毛果芸香碱 动眼神经胆碱能神经 悬韧带 向瞳孔中心收缩悬韧带,睫状小带放松 睫状肌松弛而退向外缘,悬韧带拉紧 外界 晶状体变凸屈光度增加 晶状体变扁屈光度降低 只视近物(调节痉挛) 只视远物(调节麻痹) 毛果芸香碱的调节痉挛作用

  10. Pharmacological Effects • Smooth muscle • Gastrointestinal tract: relax • Genitourinary tract: relax, void slowly

  11. Pharmacological Effects • Cardiovascular system: • Heart rate:Lower doses: Presynaptic receptor blocked bradycardia • At moderate to high therapeutic doses: tachycardia • Atrioventricular conduction • In toxic concentrations: intraventricular conduction block

  12. Pharmacological Effects • blood vessel and pressure • Vasodilation and hypopiesis caused by cholinnergic nerve can be blocked • At toxic doses, cutaneous vasodilation

  13. Pharmacological Effects • CNS • At normal doses, minimal stimulant effect • In toxic doses, excitement, agitation, hallucinations and coma

  14. Clinical uses • Relieve hyperkinesia • Inhibit secretion • Ophthalmology: iritis, optometry • Arrhythmia • shock • Cholinergic poisoning

  15. Clinical uses • 2001年 1月11日 羊城晚报(成都消息) 37岁男性,因家庭纠纷喝乐果中毒。昏迷,每30分钟用5支阿托品,无效 每10分钟用5支,无效 每5分钟用10支,连续使用72小时,总共用了1700支,850 mg 病人清醒,生命体征趋向平稳。(阿托品的 最低致死量为成人80-130 mg ,儿童10 mg )。

  16. Adverse effects • Dry mouth, mydriasis, tachycardia, hot and flushed skin, agitation and delirium • Hyperthermic effects: dangerous when overdose in infants/children • CNS: hallucinations, coma

  17. Rescue • Catharsis • Physostigmine • CNS: diazepam

  18. Anisodamine • Pharmacodynamics: similar to atropine • Clinical uses: shock

  19. Scopolamine • CNS: inhibited • Take before anaesthesia • motion sickness • Parkinson’s disease

  20. mydriatic

  21. Quaternary antimuscarinic drug: propantheline bromide • Triple antimuscarinic drug: • Pakinson’s disease • benactyzine

  22. Pirenzepin • Block M1, M4 receptor selectively • Ulcer, chronic bronchitis

  23. NN Cholinoceptor Blocking Drugs • ganglionic blocking drugs • Mecamylamine, trimetaphan camsilate

  24. pharmacodynamics • Block N1-receptors in ganglion competitively, decrease blood pressure • Small artery Relax, decrease blood vessle resistance • Venulae relax, decrease blood volume returing to heart

  25. Clinical use Decompression in anesthesia and operation of aortic aneurysm

  26. Adverse response Much and severe adverse responses:postural hypotension, retention of urine, etc.

  27. N2 Cholinoceptor Blocking Drugs • Skeletal muscle relaxants • It combines with N2-receptor of motor end-plate on postsynaptic membrane, the transmission of nerve impulse is blocked, leading to skeletal muscle relaxation.

  28. divide into two classes on the basis of their mechanism of action • Depolarizing muscular relaxants: succinylcholine • Nondepolarizing muscular relaxants: d-tubercurarine

  29. Depolarizing muscular relaxants • Mechnism • Binds to Nm receptor • Depolarize longer than Ach • Depolarization nondepolarization

  30. Depolarizing muscular relaxants • Quiver before relaxation • Acute tolerance • Cholinesterase inhibitors can strength its effects • Can not block NN-receptors in ganglion

  31. Succinylcholine • Clinical uses: • Guttural muscle are more sensitive to succinylcholine • Bronchoscope examination, esophagoscope examination

  32. Adverse responses • Asphyxia • Fascicle quiver • blood plasma • Idiosyncratic reaction

  33. Nondepolarizing muscular relaxants • d-tubercurarine

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