‘Drug repurposing’ - as the term suggests, deals with identifying new use of an existing drug.
In principle, it involves discovering a new mechanism of action of the drug that may influence the biological pathway(s) implicated in a disease.
A very recent repurposing effort is the use of existing anti-viral drugs/drug-candidates like Remdesivir, EIDD-2801, Lopinavir against SARS-CoV2 pandemic.
Development of a new drug is a highly time consuming process while repurposing an existing drug saves the hassle for the regulatory complications while the safety data is already available and the investments are relatively less. Besides, drug repurposing is usually the choice of approach for finding pharmacological solutions against a rare disease where the investment is scarce or not for profit. Therefore, in the past decade, drug repurposing has gained popularity as a quicker alternative to the traditional drug discovery strategies in many therapeutic areas.
Over the last decade our group has been identifying repurpose-able molecules against protein targets implicated in diseases like: TB, Malaria, Candidiasis, Cancer, Covid19 etc. We have demonstrated the use of target-centric (both from structural as well as sequence perspective) and ligand-centric approaches using our in-house pipelines. The NOD webserver is one such in silico pipeline which primarily uses the sequence information of query protein(s) to suggest suitable known drugs/drug candidates (as available in the DrugBank) which are likely to bind to the protein of interest.