This week, the Food and Drug Administration announced that it may withdraw its approval for generic versions of the medication Concerta (methylphenidate). The prescription drug is an extended-release version of Ritalin, used in the treatment of “attention deficit hyperactivity disorder,” or ADHD. The two manufacturers of the generic version are Mallinckrodt and UCB/Kremers Urban (formerly Kudco Ireland). According to FDA officials, these companies have been unable to provide evidence that their products are bioequivalent to the branded version.

The FDA’s concerns were first expressed nearly two years ago. At that time, the federal regulatory agency did an in-depth analysis of adverse event reports, leading to a re-evaluation of data that had been submitted earlier. After conducting a number of laboratory tests, the FDA concluded that the generic versions of Concerta may not have the same therapeutic effects as the branded drug. The problem was in the release time.  Concerta, manufactured by Bayer subsidiary Janssen Pharmaceuticals, is designed to release its active ingredients over a period of ten to twelve hours. The generic versions release the medication into the system at a slower rate – meaning that patients do not necessarily experience the same effects.

What this means for Mallinckroft and UCB/Kremers Urban is a change in the equivalence rating for their products. When first approved, that rating was “AB,” meaning that the generic version is virtually identical to the brand name drug. This was changed to “BX.” While the generic drug can still be approved, it cannot be automatically substituted for the branded version by pharmacists. The two drug manufacturers were then asked to confirm the bioequivalence of their versions within 180 days or discontinue their manufacture and marketing. Last year, Mallinckrodt filed a lawsuit against the FDA, challenging the FDA’s reclassification of its product. In that case, the judge dismissed three of the company’s claims and ruled against it on two others.

The drug companies in question have failed to take either of these actions. Now, as a result, the FDA is considering taking direct action in pulling the generics off of pharmacy shelves. As a result, shares of the company that markets and distributes generic methylphenidate fell by nearly 13% this week.

It should be noted that Janssen offers its own generic version of Concerta, which is sold under the brand name Actavis. That version has been demonstrated to be bioequivalent to Concerta. Methylphenidate has been linked to a number of harmful, and even deadly side effects, the most serious of which are suicidal thoughts – upon which many patients have tragically acted. Other side effects include erratic behavior and insomnia. These side effects have been the cause of action in a growing number of lawsuits around the country.