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Maruthi Prasad PalthurMaruthi Prasad Palthur is a senior director of technical operations and regulatory affairs at Indigene Pharmaceuticals Inc.

The average length of time from target discovery to approval of a new drug currently averages 13 years, the failure rate exceeds 95 percent, and after adjusting for all the failures the cost per successful drug exceeds $1 billion. As serendipitous discoveries diminish, a transformative approach of finding innovative ways to position approved drugs or abandoned clinical candidates in new disease areas has emerged. This sort of approach, with its scope from obvious to the progressive innovation goes by a variety of terms: drug recycling, drug repurposing, drug repositioning, drug rescuing, drug rediscovery, etc.

Drug repurposing in general refers to the study of small molecules and biologics to determine if they are safe and effective for treating multiple disease states. It has been in occurrence since the early 1990s, mostly as a serendipitous process, or as conventional life-cycle management approach. Examples of drug repurposing are numerous. In recent years, however, drug repurposing has increasingly been fueled by diverse factors, including key patent expirations, advances in science and technology and emergence of proprietary discovery engines. Indeed, most pharma companies that were previously reluctant to use repurposing strategies earlier have started to adopt drug repurposing as a core research and development strategy. In addition, confidence in integrated scientific enterprise and support from government initiatives and public funding has fostered new partnerships that could facilitate drug repurposing. The European project PONTE and initiatives from the National Center for Advancing Translational Sciences (NCATS) are acknowledged as key programs in this regard.

The promise of drug repurposing is compelling, and its potential to bridge the innovation gap cannot be ruled out. Repurposing is not limited to much emphasized rare and neglected diseases; it may be applied across a broad range of therapeutic needs. In addition, the scope of repurposing is extended to the repurposing of excipients as therapeutic agents. For example, the NIH initiation of phase I clinical trial to evaluate the safety and effectiveness of cyclodextrin as a potential therapy for Niemann-Pick type C1 by repurposing cyclodextrin.

In an era where blockbuster drugs are hard to come by, drug repurposing holds much appeal and has the potential to accelerate the drug discovery and innovation in our understanding of the basic biology of disease. The nature and scope of repurposing will hopefully evolve, yielding a much needed breakthrough.