Grapefruit Juice (GFJ)- I'd toyed with the thought of employing grapefruit juice for a long time but have read through combined experiences. Not too long ago I read that it won't inhibit CYP2D6 but rahter 3A4 which is chargeable for conversion of codeine into norcodeine. In principle by inhibiting 3A4 you allow far more codeine for 2D6 to become mo