This is really scary, and yet not surprising. Apparently the FDA approved a generic version of Wellbutrine XL 5 years ago. This generic version came in both 150mg and 300mg versions. Immediately after patients started to use the generic version of this popular drug, complaints of side-effects and ineffectiveness started rolling in for the 300mg version. Turns out the FDA did not test the 300mg version and just approved it based on assumptions from the 150mg which was tested. It took them 5 years (!) to then follow up on complaints and do their own study which found the drug ineffective. It then took them another 5 months to do a press release and recall the drug.
http://www.forbes.com/sites/davidmaris/2012/10/10/fda-recall-points-to-serious-problems-at-the-fda/