The information in this section provides an overview of what drug repurposing is, its benefits and how it differs from other drug development techniques.

Drug repurposing, at its simplest, can be considered as a type of recycling. It involves taking an existing drug already approved for human use in one disease and investigating whether it can be used to treat another condition. This idea can then be tested through a clinical trial to confirm its efficacy (effect) in the new patient population, with the ultimate aim of achieving approval of the drug for the new condition (indication).

De novo drug development is often described as the ‘traditional’ route used to produce treatments and involves generating a completely new drug for a particular condition, from scratch. The process of de novo drug discovery begins with the identification of a target biological process, synthesis of a novel compound with desirable biological activity and compound screening. A candidate drug is identified through this process and taken to preclinical development, followed by clinical trial testing. Drug repurposing differs from de novo drug development in that the medication in question already exists, thereby removing the need for synthesis of a new compound. The advantages of this strategy are discussed in the ‘benefits of drug repurposing’ section later in the course.