It’s been almost 20 years since Canadian David G. Bailey, PhD, reported his
surprising finding that taking certain medications, including commonly
prescribed blood pressure medications, with grapefruit juice increases the
body’s absorbency rate of these particular drugs, causing the drugs to be
absorbed in such quantities that the therapeutic effect can be heightened to the
point of threatened overdose. Earlier today, Bailey reported to the American
Chemical Society that further research has proven that grapefruit juice has just
the opposite effect on other drugs, hindering their absorption in ways that
render them useless in many cases.
Bailey, professor of clinical pharmacology at the University of Western Ontario,
presented his findings at the 236th national meeting of the chemical society,
where he reported similar absorbency-blocking effects in orange and apple
juices, too. It is Bailey’s recommendation that, unless directed otherwise,
anyone taking prescription medications of any kind do so with water only for the
safest and most beneficial outcome.
Bailey’s research team studied three groups of individuals taking fexofenadine,
an antihistamine. One group took the antihistamine with grapefruit juice;
another with water laced with naringin, the substance that makes grapefruit
juice taste bitter; and the third group took the antihistamine with just water.
Analysis revealed that the grapefruit juice hindered absorption by as much as
half over the group taking the medication with water alone. The difference is
said to be enough to generate a critical difference in the treatment of many
serious medical problems.
Calling his findings merely the “tip of the iceberg,” Bailey expressed
confidence that more research will reveal more interactions between drugs and
the liquids they are taken with. For the moment, however, some of the drugs that
are known to be not fully absorbed when taken with grapefruit, orange, and apple
juices include:
* the anticancer agent etoposide;
* beta blockers atenolol, celiprolol, and talinolol, frequently prescribed for
hypertension and to prevent heart attacks;
* cyclosporine, the drug that helps prevent organ rejection after transplants;
and
* the antibiotics ciprofloxacin, levofloxacin, and itraconazole.
Source: American Chemical Society
