Drug Repurposing: Accelerating New Therapeutic Discoveries From Old Molecules (1990–2025)

Drug repurposing involves finding new uses for existing drugs, significantly reducing the time, cost, and risk associated with traditional drug discovery. This approach has evolved from chance discoveries, like minoxidil's transition from an antihypertensive to a hair-growth agent, to a systematic, data-driven process using bioinformatics and AI. Advances in genomics and big-data analytics have made repurposing more predictive. The COVID-19 pandemic highlighted its potential, as existing drugs were rapidly tested for new therapeutic uses. The review discusses the historical development, global milestones, and future regulatory challenges of drug repurposing.