Drug Repurposing

Abstract

Drug repurposing involves exploring new medical uses for existing drugs, including approved, discontinued, shelved and investigational therapeutics. As the new indication is built on already available safety, pharmacokinetic and manufacturing data, drug repurposing represents an expedited way to develop innovative medications, and has found especial interest in the fields of rare and neglected conditions. It is estimated that about one third of recent approvals correspond to repurposing examples, and different public initiatives have been launched to foster the exploration of repurposing opportunities. The present chapter reviews classical and recent examples of off-label use, drug rescue and drug repositioning at different stages of the drug development process, from sildenafil to aspirin, from thalidomide to adalimumab, among many others. It also discusses challenges and opportunities of drug repurposing, from commercial and legal obstacles to expansion of the drug repurposing horizons in the context of precision medicine and polypharmacology. At last, modern approximations to explore repurposing prospects in a systematic manner are summarized.