Drug development and pre-clinical trials focus on non-human subjects and work on animals such as rats. This is the most inexpensive phase of testing.
The Food and Drug Administration mandates a 3 phase clinical trial testing that tests for side effects and the effectiveness of the drug with a single phase clinical trial costing upwards of $100 million.
After a drug has passed through all three phases, the pharmaceutical company can move forward with a New Drug Application from the FDA.  In 2014, the FDA charged between $1 million to $2 million for an NDA.