This is written by a former editor of one of my favorite periodicals, the New England Journal of Medicine:
The Truth About the Drug Companies: How They Deceive Us and What to Do About It
The next title is only partly about drug companies, but I also liked it a lot, and it is along the muckraking lines you suggest in your OP:
The Truth in Small Doses: Why We're Losing the War on Cancer-and How to Win It
I'm trying to think of a pro-pharmaceutical industry book to give some balance here, but I can't think of one I have finished.