MDO means Multi-Dimensional Optimization. This describes not a single technology but an approach to using multiple screening platforms in parallel to guide optimization of bioactive compounds on many different parameters at the same time. Activity in the targeted biological system is only one of many virtues that a future drug candidate must possess. To qualify as a potential therapeutic agent, a molecule has to have ideal molecular properties (solubility, permeability through cellular membranes, molecular weight, etc.), good resistance to the breakdown processes active in the body and get a clean bill on initial safety screening. A number of different in vitro assays look at all these aspects, allowing chemists and biologists to work on multiple parameters at once in their quest for the most promising clinical candidate.