From chance discoveries to seeking ‘magic bullets’ and now computer-aided technologies for drug discoveries. A number of drugs have been ‘rediscovered’ or ‘redeveloped’ for completely different conditions – they get ‘a second life’:

MacPherson, R. (2015). “The curious stories of drugs with two lives: a new paradigm in drug development.” Journal of the Royal Society of Medicine 108(7): 255-258. http://jrs.sagepub.com/content/108/7/255.full.pdf+html?rss=1