linking vioxx to heart attacks. the fda denies it ignored the warning. the controversy surrounding vioxx and other drugs got us wondering, how strong is the safety net that is supposed to make sure that billion dollar blockbuster drug of today won't be the dangerous drug of tomorrow? tonight, we go undercover taking our hidden cameras as we investigate just how reliably drugs are tested before they reach our pharmacy shelves. who actually tests the drugs you take? who are they being tested on? >> translator: out of desperation i had to participate in the study. >> are there companies out there that would be willing to help us get approval to test aa drug as unsafe as vioxx? >> we can do that. >> coming up, we set up a fictitious company and got the okay to test a drug already taken off the market. >> it's petrifying. >> that's a strong word. >> we're talking about people's lives here. >> when the hansen files continues. whee! whee! wheeeeeeeee! ah heads up. wheeeeeeeeeeee! everything you love about geico, now mobile