in vivo lead discovery/lead optimization is an important stage using animal models of disease to assess the target mechanism of action, efficacy, safety profiling, unpredicted toxicity and further investigation of the drug metabolism and pharmacokinetics (DMPK) properties. Compared to in vivo screening, in vivo testing is better suited for observing the overall effects of an experiment on a living subject. In addition, whole-organism in vivo screening holds several advantages to small molecule discovery for its target agonistic and holistic. The in vivo experiments of drug discovery give convincing evidence for preclinical trials at the physiological level.