Grapefruit Juice (GFJ)- I'd toyed with the thought of working with grapefruit juice for years but have examine blended stories. A short while ago I examine that it isn't going to inhibit CYP2D6 but rahter 3A4 which is to blame for conversion of codeine into norcodeine. In concept by inhibiting 3A4 you leave far more codeine for 2D6 to develop into