PPIG and kidney disorder: Of note, drug efficacy is a highly complex process which depends on several factors, including the xenobiotic’s physicochemical properties, the route of administration, the characteristics of the formulation and characteristics of the recipient, affecting the absorption, distribution, metabolism and excretion, e.g., cytochrome P450 enzymes (CYP) activity, liver or kidney diseases and underlying physiological properties of the gastrointestinal tract.