Grapefruit, orange and apple juices can harm the body's ability to absorb certain medications and make the drugs less effective, said a Canadian study released last week in the United States.

The research showed that these juices can decrease the effectiveness of certain drugs used to treat heart disease, cancer, organ-transplant rejection and infection, "potentially wiping out their beneficial effects," it said.

David Bailey, a professor of clinical pharmacology with the University of Western Ontario and leader of the study, was the first researcher to identify grapefruit juice's potential to increase the absorption of certain drugs two decades ago, possibly turning some doses toxic.

The new findings came as part of his continuing research on the subject, and were presented at the 236th annual meeting of the American Chemical Society on Philadelphia, Pennsylvania.

"Recently, we discovered that grapefruit and these other fruit juices substantially decrease the oral absorption of certain drugs undergoing intestinal uptake transport," AFP quoted Bailey as saying.

"The concern is loss of benefit of medications essential for the treatment of serious medical conditions."

Healthy volunteers took fexofenadine, an antihistamine used to fight allergies, along with either a glass of grapefruit juice, a glass of water with naringin (which gives the bitter taste to grapefruit juice), or plain water.

Those who drank the grapefruit juice absorbed only half the amount of fexofenadine, compared to those who drank plain water.

Researchers said the water with naringin served to block "a key drug uptake transporter, called OATP1A2, involved in shuttling drugs from the small intestine to the bloodstream."

Among the drugs affected by consumption of grapefruit, orange and apple juices are: etoposide, an anticancer agent; beta blockers (atenolol, celiprolol, talinolol) used to treat high blood pressure and prevent heart attacks; and certain antibiotics (ciprofloxacin, levofloxacin, itraconazole).

The drug-lowering interaction also affected cyclosporine, a drug taken to prevent rejection of transplanted organs, and more drugs were expected to be added to the list as the research continued.

Bailey said patients should consult with a doctor about taking medications with juice, and stick to plain water when taking most medications.

8月25日——柚子汁、橙汁、苹果汁会损害身体吸收某些药物的功能，从而降低药物的功效。上周在美国发表的一篇加拿大的研究如此写道。

此研究表明，这些果汁会降低某些用来治疗心脏病、癌症、以及器官移植排斥和传染的药物的效力,

潜在着消除药物有益作用的可能。

西安大略大学的临床药理学专家David Bailey，这次研究的负责人，是两年前第一个证明柚子汁可能增加某种药物吸收的人，可能会改变一些引起中毒的药剂量。

这个新的发现作为他在这个专题持续研究的一个部分，并且在宾夕法尼亚州费城的美国化学协会第236届的年会上发表。

“最近，我们发现柚子汁和其他果汁大大地减少某些口服药物在肠道内摄入转移的量。”支持Bailey的AFP如是说。

“真正的担忧是药物失去了其对于治疗某些严重的病情的本质优势。”

健康的志愿者服用fexofenadine，一种用于治疗过敏症的抗组织胺药，分别用一杯柚子汁、泡柚皮甙的水和纯水送服。

研究者说，喝了泡有柚皮甙的水会阻碍了OATP1A2，这种物质有重要的药物转移功能，帮助药物从小肠转移入血液中。

那些用柚子汁送服的对fexofenadine的吸收量仅为那些用纯水送服的人的一半。

受柚子，橙子，和苹果果汁的消费量影响的药物中有：依托泊苷，一种抗癌作用剂；β-受体阻滞药（阿替洛尔，塞替洛尔，他林洛尔），一种用来治疗高血压和防止心脏病发作的；还有一些抗生素（环丙沙星，氧氟沙星，伊曲康唑）

这种“柚子汁效应”也影响降低了用来预防器官移植排斥的环孢霉素的功效。随着研究的进行将会有更多的药物加入到这个列表中。

Bailey说病人用果汁送服药物时应咨询医生的意见，并且服用大多数药物时应坚持用白开水送服。