indications (DeBusk et al. 2004). It is advantageous to the patients as medications for

diseases, which were earlier not treatable, can be easily accessed, as knowledge

about possible side effects, pharmacokinetics and interactions with other drugs

already exists in various online resources. Further, rare diseases wherein no drugs

have been developed or discovered can also be targeted with known drugs. To this

effect, the US Food and Drug Administration (FDA) launched a database of

approved drugs, which are promising to be repositioned to orphan/rare diseases

(Schenone et al. 2013). Also, a “high-throughput” in vivo pharmacology platform

theraTRACE1 has been developed for drug repurposing (Boran and Iyengar 2010).

Repurposing of chemicals and natural products that differ from drugs, such as herbal

remedies or compounds used in traditional Chinese medicine (TCM), has led to the

advent of TCM database (Baron 2012). Therefore, the availability of a large number

of online resources is opening up newer avenues to search for targets of active

components using computational approaches.

2.5

Concluding Remarks

Polypharmacology aims to identify all the possible targets of a given compound.

However, it is highly impractical to experimentally test the binding affinities

between each drug-target pair for all the possible compounds, genes and proteins.

Therefore, drug target prediction using computational technologies plays a signifi-

cant role to sift through the big data by development of accurate, fast and robust

algorithms. These in silico tools based upon integration of knowledge and

technologies from varied disciplines, such as cheminformatics, network-systems

biology and data mining, have been successfully used to predict possible off-target

of drugs that account for their reported side effects and can be used for drug

repurposing and design of combination therapies. The fact that several drugs exert

their effect through the interaction with multiple targets is shifting the drug discovery

paradigm from the one target-one drug model to a multiple-target approach. This has

also been necessitated by the multi-faceted nature of various complex diseases, such

as neurodegenerative disorders and cancer. In spite of tremendous challenges that lie

ahead, in the years to come polypharmacology would have a major role in

transforming next-generation drug discovery and development.

References

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Ashburn TT, Thor KB (2004) Drug repositioning: identifying and developing new uses for existing

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