ALEXANDRIA, VirginiaDrinking grapefruit juice with
certain medications, including at least one widely used in cancer
treatment, may inhibit their absorption, according to an in vitro
study in the April 1999 issue of Pharmaceutical Research, a
publication of the American Association of Pharmaceutical Scientists (AAPS).
The drugs include vinblastine, cyclosporine (Sandimmune, Neoral),
losartan (Cozaar, an antihypertension agent), digoxin, and
fexofenadine (Allegra, an antihistamine).
This inhibition occurs, the researchers said, because an unknown
substance in grapefruit juice activates one of the bodys
naturally produced drug efflux mechanisms, P-glycoprotein, located in
the intestinal tract. When grapefruit juice interacts with P-glycoprotein,
the result is an increased likelihood that certain drugs will be
stopped from entering the bloodstream.