Companies that make drugs are always analyzing various compounds trying to find the ones that have the most therapeutic value. There are many steps, millions of dollars, and thousands of man hours spent on trying to get a medicine approved by the FDA. There are many steps to get your product approved before you can sell it on the open market.
Perfection and Preclinical Testing
During the first six or seven years of preclinical testing the synthesis and purification of a drug gets perfected by the manufacturer. Limited animal testing applies as well. Out of thousands of compounds that are tested, only a few will appear to have enough promise to induce a company to file an IND, or Investigational New Drug Application. If the FDA approves the IND and an Institutional Review Board approves them as well, the manufacturer can start the first part of development.