Mathematical modeling and computer simulations are emerging technologies in drug discovery, development and drug assessment for short-and long-term biological effects. They promise to be cheap, practical, sensitive and specific, and capture real aspects of the disease phenotype that is accepted as clinically and biologically meaningful. However, existing computer-based platforms are not capable of integrating complex nonlinear interactions of molecular, cellular, tissue, organ and system activities that are required in drug discovery. Novel software, ABS Technologies©, is designed on a "reductionism-integration" principle. It offers solutions with regard to rational decision making at different stages of drug development. Examples of numerical investigations into the effects of Lotronex (GSK) and benzodiazepines provided valuable information related to the dynamics of visceral perception and motility of the gut. The results revealed the intricate role of nonlinear interplay between different signaling pathways in the pathogenesis of visceral hypersensitivity and functional gastrointestinal disorders. Advantages and limitations of the use of computer-based technologies in drug discovery are briefly reviewed.