Goomba wrote:
>
> blake murphy wrote:
>
> >> SOME drugs are potentiated by grapefruit for example. That doesn't mean
> >> all drugs are. So should anyone taking any medicine give up all
> >> grapefruit products?
> >
> > well, i drink a lot of grapefruit juice, but i don't take any drugs but
> > ibuprofen. is there a site outlining metabolic effects on regular people?
> >
> > your pal,
> > blake
>
> Here ya go. a nice little cite/site for you-
> http://edis.ifas.ufl.edu/FS088

That list is dangerously incomplete. It appears
to have been compiled strictly from studies on
interactions between specific drugs and grapefruit
juice, and even with this restriction the list is
incomplete. For example, colchicine is not listed,
even though it has this interaction. Most drugs
have not been studied for their interaction with
grapefruit juice, and it would be an enormous
mistake to assume that in the absence of data
no interaction will occur.

The mechanism by which grapefruit juice interacts
with drugs is known -- it modulates P-gp.
Therefore any drug known to be a P-gp substrate
should be considered to have an interaction
unless studies show it does not. Nearly all
cancer chemotherapy drugs are known to be
P-gp substrates. I don't know of any chemotherapy
drug which is not a P-gp substrate, but I suppose
they might exist.

Also, that web site says "Juices from oranges or
other citrus fruits do not interact with medications
in the same way." That's not true. Orange juice
also contains the compound in grapefruit juice
responsible for modulating P-gp. It contains
less of it, so it would be reasonable to say the
risk is lower, but it is not reasonable to say
this interaction doesn't occur at all.