Drug repurposing is the concept of finding a new use for an existing medicine used to treat one Condition to treat a different one. Repurposed drugs have the potential to get to Patients quicker and are often cheaper to produce because the early phases of drug design and development can often be skipped due to existing data on Safety , Efficacy and dosing from the pre-clinical and clinical testing undertaken for the original therapeutic Indication .

Most repurposed drugs still need to undergo new Clinical trials to prove that they are effective in the new indication. An example of a successfully repurposed drug is Alpelisib. Originally designed to treat some breast cancers, it has been repurposed to treat PIK3CA overgrowth spectrum (PROS). See a more detailed case study below.

Drug repurposing consists of finding new therapeutic uses for existing medicines. Building on the knowledge previously generated on safety and effectiveness for a specific drug, researchers can explore new indications, potentially leveraging those steps already completed during the drug development process. This means that scientific knowledge and resources are used efficiently, and research can move faster to provide patients with innovative therapeutic options where no or limited treatments are available. Drug repurposing potentially stands for more efficient research with high social impact as it offers a plausible and relatively quick route to a much-needed treatment.