In general terms, it is recommended to use several in silico tools and to agree on the properties of ADMET with the available methodologies to minimize the statistical variations of the model used. PAINS can be either synthetic, semi-synthetic, or natural compounds that have triggered biological alterations: oxidation by redox mechanisms, covalent interaction with proteins, metal chelation, and alteration of the lipid layer of cell membranes. These disturbances affect biological assays by interference with fluorescence and structural decomposition of the tested compounds [131], making the identification of these interfering compounds in chemical libraries a difficult problem .