 To comply with push for the development of alternative testing methods, increasingly sophisticated "in vitro" experiments are now collecting numerous, complex, and challenging data that can be integrated into mathematical models.IVIVE in pharmacology can be used to assess pharmacokinetics (PK) or pharmacodynamics (PD)..Since biological perturbation depends on concentration of the toxicant as well as exposure duration of a candidate drug (parent molecule or metabolites) at that target site, in vivo tissue and organ effects can either be completely different or similar to those observed "in vitro".