Morphine itself, however, is not affected by grapefruit juice, as it is not metabolized by the cytochrome P450 system.
* Cyclosporine (Neoral).
Blood levels
of cyclosporine are increased if taken with grapefruit juice. A plausible mechanism involves the combined inhibition of enteric CYP3A4 and P-glycoprotein, which potentially leads to serious adverse events (e.g., nephrotoxicity).Blood levels of tacrolimus (Prograf) can also be equally affected for the same reason as with cyclosporine.