*2.2.1 Clinical analysis (human experiments)*

Clinical trials providing positive outcomes are quite rare as most of the drugs fail during Phase II/III trials. But many drugs which already have been marketed during post-marketing surveillance provides different outcome. Some may display different adverse events and some may treat specific kinds of disease with no labeled indication. Many drugs have been repurposed with the help of these trials. Some such examples are apomorphine was indicated for Parkinson's disease and it was repurposed for erectile dysfunction, drospirenone—oral contraceptive and repurposed for hypertension, dapoxetine—analgesia and depression and repurposed for hypertension [3]. These are very few examples of clinically repurposed drugs, there are many such drugs which have been repurposed with many new indications [1].
