I used to work in clinical trials, and while I cannot comment on exact figures, the drug companies pay a lot of money over a very long period to release a drug. The big problem is that they only have 3 to 5 years to make all the money back and get enough of a profit to develop more drugs. Not every clinical trial actually works out, and the courts will be a constant problem for every drug.

Do some research on the financial documents of the companies that do the clinical trials.