Leblond et al. showed that CKD in rats is associated with a decrease in intestinal CYP1A1 and CYP3A2 activities [60], whereas intestinal CYP3A function was investigated in several clinical studies by using phenotyping probes and appeared not to be substantially altered in patients with end-stage kidney disease (ESKD) [61–63]. Here, CYP3A4 is linked to chronic kidney disease.