The real problem isn't drug repurposing, but off-label promotion. If you want to take a drug through FDA approval for another set of indications, that's fine and dandy. What isn't cool is actively promoting the use of a drug without market approval - having reps drop subtle hints, funding third-party publication, paying doctors to speak at conferences about their off-label prescribing and so on.

Eli Lilly, Pfizer and AstraZeneca have collectively paid out more than $2.5bn in settlements over the off-label promotion of atypical antipsychotics. The drugs that they unlawfully promoted are now being used widely for the treatment of a variety of conditions for which there is little evidence of efficacy. Lilly were marketing Zyprexa for the treatment of dementia, in spite of having extensive unpublished research showing that it was ineffective.

Atypical antipsychotics are being used by far too many psychiatrists as a catch-all where other lines of treatment have failed - OCD, autism, PTSD, ADHD, anorexia, substance abuse, you name it. In most cases the evidence of efficacy is slim-to-none. That's not medicine, it's quackery. Frankly, I'd be happier if they were prescribing placebo; Nobody has ever died from the side effects of sugar pills.