Newsletter No. 383

4 No. 383, 19.9.2011 中藥與西藥： 是友是敵？ Chinese and Western Medicine : Friends or Foes? 在 香港，很多人患病時 都抱着不管中醫西 醫，有療效就是好醫的態度， 所以中西藥不拒，其實後果可以 很嚴重。以中藥丹參為例，這種多 年生草本藥用的是根部，肥厚而色 赤，味苦辛，性微寒，功能祛瘀止痛、活 血通經，對擴張血管很有效，《神農本草 經》列為上品藥材，國內有製成中成藥，用以 醫治冠心病和心絞痛等症狀。不過病患者如果正 在服用西藥裏俗稱「薄血丸」的華法林（warfarin），則 千萬不可食丹參或者含丹參成分的中藥。 生物醫學學院的 楊鶴強 教授解釋說：「華法林是抗凝血藥 類別藥物，所謂『薄血』其實是令肝臟減少生產某幾類令 血液凝固的蛋白質，通常心律不正或者裝了人工心瓣的病 者都須服用。丹參有活血作用，和人參相同。中國人的民 間智慧說臨盆的孕婦或者要接受外科手術的病人不可吃 參，因恐怕血流不止，道理便在這裏。丹參和華法林都有 減低血液凝固的效果，所以兩者不可同時服用，否則副作 用會加劇，例如身體無故青腫、流鼻血和牙血、小便帶血 等。」 楊鶴強教授的專長是藥物代謝和藥物動力學，二十多年前 加入中大藥理學系時，即應 陳金泉 教授之邀合作研究丹 參，當時就是因為出現了華法林和丹參相互影響的個案， 大家便着手研究，以找出原因。他指出，傳統中醫藥在內地 和香港以至亞洲不少地區一直都有很大的市場，很多人身 體不適時都有中西藥交替甚至並用的習慣，但儘管中西醫 藥結合的發展已有相當歷史，對中西藥相互作用的研究和 認識仍是長路漫漫，有待探索。據楊教授說，近年在歐美 國家大行其道的天然和保健產品很多都是草藥製成品，所 以草藥研究愈加得到重視，也對中藥研究起了推動作用。 「中藥和西藥是兩個截然不同的系統，」楊鶴強說。「西藥 的理想是製造出一種純淨的化合物，成分、效力以至副作 用都一清二楚。中藥不同，以複方為主，一帖藥裏可以有十 多二十種藥材，種種不同，煎煮後藥材原本的化學成分已 改變，要研究是非常困難的事。我們做的也是單一種藥材 的研究，目前集中在傳統中藥及其他自然產品與西藥的相 互作用，以及其藥物代謝和毒理上的意義。」 以丹參為例，已知的成分有四十多種，包括水溶性成分的 酚酸和脂溶性的丹參酮，兩者都各有藥理上的作用。現時 中大的研究已知丹參的水溶性成分對西藥不會引起代謝 性的相互作用，但丹參酮對某幾種重要的藥物代謝酶則會 造成間接的代謝作用。所謂藥物代謝作用，指的是藥物在 人體內的分量和有效力時間。以中西藥的相互作用來說， 如果某種中藥成分令病人所服西藥的代謝作用加快，令體 內西藥成分減少，即是該西藥無效，反之，則會出現藥性 或副作用加劇。 丹參和華法林的藥性或毒性有相互作 用，即是中醫所說的相沖，是西方醫學 界普通接受的其中一項研究結果。當然 有持不同意見者，認為沒有全面的臨床 試驗，只可以視作個別的案例。不過近 年西方亦開始接受中藥並非是單一體 的這個特點。中西醫藥如果能夠相輔 相成，對醫學可以是無可限量的發展， 但兩者要結合，首先要互相接受。但中 藥必須要經西藥式的測試才可以為西 方接受嗎？「這似乎是不能不走的一條 路，」楊鶴強說。「其實中藥的研究這 十多年來進展得很快，主要是儀器先進 了，可以更詳細地分析藥物的成分。中 藥和西藥究竟是友是敵，就像一幅有十 萬碎塊的大拼圖，我們現在拼砌的只是其中的幾塊。」 I n Hong Kong, many patients are desperate to get a hold of whatever medicine they believe would work, be it Chinese herbs or Western remedies. But the mixed use of Chinese and Western medicine can lead to serious consequences. Take the Chinese herb danshen ( Savia miltiorrhiza ), the root of a perennial plant. It looks thick and red, and tastes pungent and bitter. Danshen is known to have the effects of relieving blood stasis, alleviating pain, increasing blood circulation, facilitating smooth menstruation and widening blood vessels. It is ranked as a first-class herbal medicine in Shennong’s Herbal , a classical text on Chinese medicine. Danshen can be found in many over-the-counter Chinese herbal drugs for coronary heart disease and angina. However, patients on warfarin, which is commonly known as a blood thinner, should avoid danshen or any medicine with danshen as an ingredient. ‘Warfarin is an anticoagulant, which acts on the liver to decrease the quantity of a few key proteins in blood which allow blood to clot,’ explained Prof. Yeung Hok-keung John of the School of Biomedical Sciences. ‘It is usually prescribed to patients with arrhythmia or those who have undergone mechanical heart valve replacement. Danshen can improve blood circulation, just as ginseng does. That’s why folk wisdom advises against prescribing ginseng to pregnant women about to give birth or those who are going to have surgery for fear of haemorrhage. Both danshen and warfarin have the effect of anticoagulation. People should avoid using them together, otherwise their side effects like bruises, nosebleeding, gum bleeding, blood in urine will be exacerbated.’ Professor Yeung is an expert on drug metabolism and pharmacokinetics. When he joined the then Department of Pharmacology some 20 years ago, there were cases of interaction between danshen and warfarin. He was invited by Prof. Kelvin K.C. Chan to study danshen together, trying to unravel the mysteries of this herb-drug interaction. Chinese medicine has always been popular in mainland China, Hong Kong and many Asian regions. It is very common for people in these regions to use Chinese herbs and Western medicine alternatively or together. But he said, although people have long used Chinese herbs and Western medicine together, we still have a long way to go before we can be clear about the interactions between them. According to Professor Yeung, the studies on herbal medicine have gained considerable momentum because of the popularity of herbal health supplements in European and American countries. ‘Chinese and Western medicine are two totally different systems,’ said Professor Yeung. ‘In Western medicine, a drug must be a pure chemical, whose constituents and effects are clear. But Chinese medicine is characterized by its use of herbal compounds. A Chinese herbal 洞 明 集 In Plain View