毛地黃素

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在2008年3月24日 (一) 10:56所做的修訂版本 (編輯)
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* 能藉抑制心臟細胞膜上Na<sup>+</sup><sup></sup>、K<sup>+</sup><sup></sup>-ATPase 的活性增強心房及心室的收縮力,有強心的功能。<br> * 能藉抑制心臟細胞膜上Na<sup>+</sup><sup></sup>、K<sup>+</sup><sup></sup>-ATPase 的活性增強心房及心室的收縮力,有強心的功能。<br>
* 減少通過房室結的神經衝動傳導,抗心律不整,在心室顫動或心房撲動時協助控制心跳速率。<br> * 減少通過房室結的神經衝動傳導,抗心律不整,在心室顫動或心房撲動時協助控制心跳速率。<br>
 +
 +== 作用機制 ==
 +
 +抑制 Na-K ATPase 活性,增加 Na-Ca 交換,增加細胞內 Ca<sup><sup>2</sup><sup></sup>+</sup><sup></sup> 濃度而發揮其正性肌力作用,除此之外,還通過降低神經內分泌系統的活性引發對心衰的治療作用。Digoxin binds to a site on the extracellular aspect of the α-subunit of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes). This causes an increase in the level of sodium ions in the myocytes, which then leads to a rise in the level of calcium ions. The proposed mechanism is the following: inhibition of the Na+/K+ pump leads to increased intracellular Na+ levels, which in turn slows down the extrusion of Ca2+ by the Na+/Ca2+ exchange pump that relies on the high Na+ gradient. This effect causes an increase in the length of Phase 4 and Phase 0 of the cardiac action potential, which when combined with the effects of Digoxin on the parasympathetic nervous system, lead to a decrease in heart rate. Increased amounts of Ca2+ are then stored in the sarcoplasmic reticulum and released by each action potential, which is unchanged by digoxin. This leads to increased contractility of the heart. This is a different mechanism from that of catecholamines.
 +
 +Digoxin also increases vagal activity via its action on the central nervous system, thus decreasing the conduction of electrical impulses through the AV node. This is important for its clinical use in different arrhythmias (see below)
 +
 +<br>
== 注意事項 == == 注意事項 ==
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[http://www.cgu.edu.tw/GE/nature_plan/94/present_ppt_c/c2_heart.pdf]曲線上的人心 [http://www.cgu.edu.tw/GE/nature_plan/94/present_ppt_c/c2_heart.pdf]曲線上的人心
 +
 +[http://www.adoop.cn/medical-insurance/show-1535-1.html] Adoop

在2008年3月24日 (一) 11:05所做的修訂版本

 

目錄

毛地黃素

  
毛地黃素(Digoxin),又名Digitalis。是由紫花毛地黃(Digitalis purpurea) 或柔毛洋地黃(Digitalis lanata)的植物體中萃取純化的心臟用毛地黃配醣(digitalis glycosides,又名醣啟)。與毛地黃素相對應的配醣體是洋地黃毒(digoxigenin)。毛地黃素廣泛地應用在許多心臟治療上,如無法由其他治療方式治療的心室顫動(atrial fibrillation)、心房撲動(atrial flutter)或心臟衰竭(heart failure)。市面上有許多藥的成分是毛地黃素,一些商品命名如隆我心(Lanoxin),Digitek以及Lanoxicaps。可利用來做成 0.05 mg/mL 的口服液以及0.25 mg/mL 或 0.5 mg/mL 的注射液。

作用

毛地黃素藥理學上的主作用是作用在心臟,但具有許多有害的副作用。主要的心臟作用是:

  • 能藉抑制心臟細胞膜上Na+、K+-ATPase 的活性增強心房及心室的收縮力,有強心的功能。
  • 減少通過房室結的神經衝動傳導,抗心律不整,在心室顫動或心房撲動時協助控制心跳速率。

作用機制

抑制 Na-K ATPase 活性,增加 Na-Ca 交換,增加細胞內 Ca2+ 濃度而發揮其正性肌力作用,除此之外,還通過降低神經內分泌系統的活性引發對心衰的治療作用。Digoxin binds to a site on the extracellular aspect of the α-subunit of the Na+/K+ ATPase pump in the membranes of heart cells (myocytes). This causes an increase in the level of sodium ions in the myocytes, which then leads to a rise in the level of calcium ions. The proposed mechanism is the following: inhibition of the Na+/K+ pump leads to increased intracellular Na+ levels, which in turn slows down the extrusion of Ca2+ by the Na+/Ca2+ exchange pump that relies on the high Na+ gradient. This effect causes an increase in the length of Phase 4 and Phase 0 of the cardiac action potential, which when combined with the effects of Digoxin on the parasympathetic nervous system, lead to a decrease in heart rate. Increased amounts of Ca2+ are then stored in the sarcoplasmic reticulum and released by each action potential, which is unchanged by digoxin. This leads to increased contractility of the heart. This is a different mechanism from that of catecholamines.

Digoxin also increases vagal activity via its action on the central nervous system, thus decreasing the conduction of electrical impulses through the AV node. This is important for its clinical use in different arrhythmias (see below)


注意事項

1. 毛地黃 (Digoxin) 乃心臟病病童常用之藥物,其作用在於增強心肌收縮的力量,以改善心臟衰竭的症狀。此外,毛地黃也會影響心臟內部的神經傳導,因此,有時也用它來治療某些心律不整疾病。

2. 任何藥物都有其效用和副作用,適量為良藥,過量則為毒藥,毛地黃亦然。故應絕對遵守醫師的囑咐,千萬不可自行增減藥量。[毛地黃過量或中毒的症狀]包括:噁心、嘔吐;頭痛、嗜睡;畏光、視力模糊;脈搏降低或不規律。

3. 為防範毛地黃過量或中毒,每次給藥前需先測量脈搏一分鐘。若嬰兒 (一歲以下) 脈搏每分鐘低於 100 次,較大兒童低於80 次,則當天不要給藥,並到醫院請教醫師調節藥量。

4. 本院兒科門診所處方的"毛地黃"為每瓶30毫升之淡粉紅色藥水,以褐色玻璃瓶包裝。服用方法為一天一次,定時服用,劑量要以吸管準確測量,吸管不要沾到寶寶的口水;同時藥瓶應避光保存 (但不需存放冰箱),以免變質。藥物需小心置放,以避免其他孩童誤食中毒。

5. 服藥的時間不限定在早上或晚上、飯前或飯後,但必須在每天固定的時間給藥。除非醫師指示,勿和其它藥物或食品混合服用。若是忘了給藥,未超過6 時之內可以補給,若已超過 6 小時,則暫停給藥一次。

6. 餵食毛地黃後若 5 到 10 分鐘內吐出來,可以再給藥一次。若隔 10 分鐘後才嘔吐,則不要再餵藥。又,若血中鉀離子過低,易引起毛地黃中毒,所以平時應多餵食病童含鉀較高 (如香蕉和柑橘類) 之水果。


參考資料

[1]馬偕紀念醫院全球網

[2]Digoxin

[3]幾種小分子藥物對類固醇激素合成與分泌的影響

[4]曲線上的人心

[5] Adoop