"A third of the clinical trial results that federal regulators reviewed to approve drugs made by large pharmaceutical companies in 2012 were never publicly reported, according to a new study that grades companies on their transparency."


https://www.washingtonpost.com/news/wonk/wp/2015/11/12/how-pharma-keeps-a-trove-of-drug-trials-out-of-public-view/?utm_source=hs_email&utm_medium=email&utm_content=23715073&_hsenc=p2ANqtz-_kW-VQ9NWOh99IPB1-c7-QSmrO-Nlrv5ylQ8UdEjMTlvtk4ylwUWxGFhWRTLleDkwtJZddCpSY5h0lGqWbhYbDgSrm1w&_hsmi=23715073

Clinical trials showing how drugs worked aren't always publicly available