As discussed in Section 2.2.2.3, most porphyrogenic drugs cause AIP attacks through impacting CYP450 metabolism, particularly through induction of, or irreversible inactivation of, CYP3A4 and CYP2C9 (Brodie, 1980; Moore and Hift, 1997; Thunell, 2000; Thunell et al., 2007). Here, CYP2C9 is linked to autoimmune pancreatitis.