Grapefruit juice and potential drug interactions.
OBJECTIVE
To review current literature pertaining to the potential interaction of several classes of drugs with grapefruit juice, and to discuss the mechanism and causative agents in such interactions.


METHODS
A MEDLINE search covering the period 1989-2002 was performed to identify review articles, studies, and case reports referencing the potential interaction of grapefruit juice with several classes of drugs. The bibliographies of the selected articles were reviewed for additional references.


METHODS
Human studies and case reports describing the mechanism and potential interaction of grapefruit juice and several classes of drugs.


METHODS
Studies were reviewed for design characteristics, as well as data relevant to the severity of a drug or drug class' interaction with grapefruit juice. Data were also extracted relevant to the possible causative agents of an interaction with grapefruit juice.


RESULTS
Grapefruit juice acts by blocking the activity of cytochrome P-450 (CYP) 3A4 isoenzyme in the intestinal wall, thereby preventing the presystemic first-pass metabolism of a wide range of drugs. Studies and case reports continue to analyze the specific active components of grapefruit juice and the medications with which it interacts.


CONCLUSIONS
Researchers continue to work to determine the constituents of grapefruit juice responsible for CYP enzyme inhibition and P-glycoprotein activation in clinical settings. Some trials have pointed researchers in the direction of compounds such as naringin, naringenin, and 6,7-dihydroxybergamottin as possible active agents. Calcium channel antagonists, neuropsychiatric medications, statins, and antihistamines are just a few of the drug classes whose actions are significantly affected by the consumption of grapefruit juice. Patients and other health care professionals need to be educated about potential drug interactions with grapefruit juice.
West Virginia University School of Pharmacy, USA.
Justin T
JT
Hare
David P
DP
Elliott