Grapefruit Juice (GFJ)- I had toyed with the idea of using grapefruit juice for a long period but have read blended reviews. Recently I read through that it does not inhibit CYP2D6 but rahter 3A4 and that is liable for conversion of codeine into norcodeine. In idea by inhibiting 3A4 you permit extra codeine for 2D6 to turn into morphine. Soon after