However, factors such as differences in age and weights of the study participants (mostly children), food effect, intestinal diseases, and a wide spectrum of CYP450 metabolizing enzymes involved in biotransformation of praziquantel (extensive first pass effect), including CYP3A, CYP1A2, CYP2C9 and CYP2C19 have been speculated12,19. This evidence concerns the gene CYP3A4 and intestinal disorder.