Drug Repositioning: A Review
Drug repositioning (also referred to as drug repurposing) the process of finding new uses of existing drugs, has been gaining popularity in recent years. The availability of several established clinical drug libraries and rapid advances in disease biology, genomics and bioinformatics has accelerated the pace of both activity-based and in silico drug repositioning. Human diseases can be caused by complex mechanisms involving aberrations in numerous proteins and pathways. With recent advances in genomics, elucidating the molecular basis of disease on a personalized level has become an attainable goal. In many cases, relevant molecular targets will be identified for which approved drugs already exist, and the potential repositioning of these drugs to a new indication can be investigated. Repositioning is an accelerated route for drug discovery because existing drugs have established clinical and pharmacokinetic data. In the more conservative approach, termed “on-target repurposing,” the drug’s known pharmacological mechanism is applied to a new therapeutic indication, which in clinical terms might be quite far removed from the original one but is known to have the same pharmacological underpinning. About 80% of drug repurposing efforts that are currently ongoing (or have already resulted in a successful relaunch) have followed this route, which must not be confused with simple line extensions, e.g., a cancer drug obtaining additional approvals for other types of cancer.