Ron-
I did a little looking (but not in depth). It seems that there are two or three ways for grapefruit juice to affect the apple cart-
1) It can influence the actions of certain enzymes (e.g. cytochrome P450) and affect serum levels of medications that are broken down by those enzymes. Depending on the medication, those levels can increase or decrease.
2) It can increase bioavailability of drugs that are absorbed from the small intestine by increasing the permeability of that barrier. This is the one that intrigues me for obvious reasons.
3) There are hints of a similar effect at your old friend the BBB, too.

Bottom line is a bit of trial and error, but it looks darned promising. -Rick

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