This is a valid point. While I won't dive into the qualms that stem from pharma companies funding and subsequently selectively choosing their trials, the case with BiDil is particularly curious [1].

When BiDil was patented, studies were carried out using _only_ African-American subjects, such that the race-specific efficacy was never actually tested. As such, the basis for the entire patent, which hinged on race specificity, has been challenged by some in the field. In my post above there's a link to a paper that came out one of the trials.

[1] - If you're interested, Ben Goldacre has a really interesting talk on the subject.

http://www.ted.com/talks/ben_goldacre_what_doctors_don_t_kno...