Influence of Fruit Juices on Drug Disposition

This paper is a nice review of the in vitro and in vivo data describing the inhibition of drug metabolism by grapefruit juice and other juices.  It turns out the story isn't so simple as in vitro results are very rarely replicated in the in vivo clinical trials.  It appears as though grapefruit juice is the only real culprit we need to worry about so far.