Most medicines are already "open source" in the sense that their patents have expired, the details are known, and any chemistry lab can make them. The problem is selling them legally as medicine! A generic medicine needs FDA approval confirming that it is biologically equivalent to an already-approved drug, which requires a human trial. https://en.wikipedia.org/wiki/Abbreviated_New_Drug_Applicati...

This process is apparently easier in the EU, but both systems are so complex that it's hard to tell exactly what makes it easier.