A meta-analysis last year linking aspirin to reduced death rates from certain types of cancer signalled the latest reinvention of this well established drug.1 Developed as an analgesic, greater understanding of its properties has led to it being used to treat stroke and reduce the risk of cardiovascular disease, and it has also been suggested to help prevent pre-eclampsia and dementia.

Aspirin is just one of many drugs that have found new uses, some before they even get to market (table⇓). Raloxifene, for osteoporosis, was a failed oral contraceptive found to increase bone density. The antidepressant fluoxetine flunked hypertension trials but affected mood. The erectile dysfunction treatment sildenafil was ineffective for angina. All three medicines were repurposed to great effect.

Discovering new uses for old drugs offers great promise for quickly bringing new therapeutic options to patient care; the lag between drug discovery and availability, often 10 years or longer, can be shortened by dusting off drugs already marketed and repurposing them. But the discoveries are not simply down to serendipity. New uses are increasingly being discovered not by pharmacologists but by computer scientists in university departments of computational drug discovery or biomedical informatics.