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 this 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

    本周在美國發表的一項加拿大研究聲稱，葡萄柚、桔子和蘋果的果汁會對人體吸收某些藥物的能力有害，而且會使藥物降低療效。

    研究表明這些果汁會降低某些藥物對治愈心臟病、癌癥以及器官移植排斥和感染的療效。研究說：“果汁會潛在地抹殺藥物的療效。”

    David Bailey 是西安大略大學臨床藥理學的教授，同時也是此項研究的領導者。二十年前他是第一個確認葡萄柚的果汁有增加吸收某些藥物潛在性的研究者，他認為果汁會有可能把一些藥劑變得有毒性。

    新的發現延續了這個課題的研究，并且發表在第236屆賓夕法尼亞州費城的美國醫學協會年會上。

    賓夕法尼亞州費城的美國醫學協會引用Bailey的話說：“最近我們發現葡萄柚和這些其它水果的果汁會在實質上降低某些在腸內吸收流動的口服藥物的吸收.”

    “讓人擔心的是那些對治愈嚴重的醫學疾病非常重要的藥物失去了藥用。”

    健康志愿者服用非索非那定— 一種用于抗過敏抗組胺藥物，同時喝一杯葡萄柚果汁、一杯柚皮甙水（使葡萄柚果汁帶有苦味）或者白水。

    和那些喝白水的人比較，那些喝了葡萄柚果汁的人僅吸收了一半量的非索非那定。

    研究者稱有柚皮甙的水能阻礙一種叫“OATP1A2的重要的藥物傳送者，它負責把藥物從小腸送到在體內循環的血液中。”

    這些受飲用葡萄柚汁、桔子汁和蘋果汁影響的藥物有：抗癌劑；用于治療高血壓和心臟病的阻滯劑（阿替洛爾，塞利洛爾，肽利諾羅）；和一些抗生素（環丙沙星，左氧氟沙星，伊曲康唑）。

    降低藥物相互作用還會影響到環孢菌素，一種用于防止器官移植排斥的藥物，而其更多的藥物還會隨著研究的進展而添加到這個名單中。

    Bailey 說病人應該咨詢醫生是否能用果汁服藥，而且在服用大多數藥物時應堅持喝白水。