Grapefruit Juice (GFJ)- I had toyed with the idea of utilizing grapefruit juice for some time but have read through combined reviews. Just lately I go through that it would not inhibit CYP2D6 but rahter 3A4 that's chargeable for conversion of codeine into norcodeine. In idea by inhibiting 3A4 you allow extra codeine for 2D6 to become morphine. Righ