Drug repurposing: new tricks for old drugs

Abstract

Drugs that have been used for indications other than their originally intended purpose date back to at least the 1950s,¹ with some authors proposing that the earliest examples date as far back as over a century ago.² Despite this, the first formal definition of drug repurposing only appeared in the literature in 2004.³ Many definitions now exist, which explain drug repurposing as a “novel way of finding new uses outside the scope of the original indication for existing drugs”.¹ Also known in the literature as “drug repositioning, drug reprofiling, drug retasking”^2,4,5 or “therapeutic switching”,⁴ this process has been popularised because of the many advantages it has over de novo drug production, in an age where time is money.