Drug Discovery and ADMET process: A Review

Pharmaceutical drug discovery is an expensive and time-consuming process. In order to have one effective and safe drug, millions of molecules are screened. A successful IND application requires that the sponsor demonstrate reasonable evidence concerning safety of the candidate molecule.  This evidence is derived from a battery of in vitro assays as well as in vivo studies using animals.  Animal studies often fail to predict clinical results due to inter-species differences in enzymes, transporters and biochemical pathways.  Although many in vitro assays use human cells, they lack the interplay of body systems and biochemical pathways.  Due to these shortcomings, both in vitro and in vivo studies often fail to predict clinical outcomes. Nearly 30% of molecules entering clinical trials fail because of insufficient safety. This inadequacy opens opportunities for new technologies that can address these issues, thereby leading to a more predictive human model. In addition, due to time-consuming and expensive nature of in vivo studies, improved in vitro assays that lead to reduction in animal usage present interesting opportunities. With these ideas in mind we framed the objective to summarize the in vitro ADME/T tests in order to better predict human clinical outcomes.