This study involves high-throughput virtual screening of vast libraries of small ligand molecules; acting to narrow the range from that of all possible small-molecule compounds (approx. 10^60 [1]), down to a focused library of which will be tested in-vitro.

When investigating drugs relevant to a disease, this vast space of possible drugs will generally be narrowed by focusing on a single protein or gene of interest at a time. Several factors are used to narrow this search-space:

1. Relevance of compounds to the biochemical pathways, via metabolite profiling, toxic chemical profiling, or network analysis (for example, see [2]).
2. The availability of compounds to be readily purchased or synthesized, which is often determined by consulting vast small-molecule databases, such as our own CCCID small-molecule database.
3. Known or predicted toxicity of the compound in humans. This is of great concern in human trials, and is one of the central reasons for the enormous cost of drug development. Fortunately, this concern is almost entirely removed by drug repurposing.