Teva Pharmaceuticals is pulling its generic version of Wellbutrin XL. After extended testing, the FDA has determined that Teva's generic isn't equivalent to the branded drug. And now, the FDA is requiring other generics companies to test whether their own versions of Wellbutrin XL are acceptable (read Bloomberg story).
For years, questions have swirled around Teva's version of the drug, sold under its own brand name, Budeprion XL. In 2007, patients raised a red flag at FDA about their generic versions of the extended-release antidepressant, saying the generic version wasn't working like the branded version did. In fact, several pharmacists teamed up with Consumer Labs to compare the extended-release brand with Teva's generic, and found that the generic released active ingredient much faster.
At the time, Teva's lawyers contended that its own testing showed that its version did meet FDA's bio-equivalence standards. The agency ended up concurring; at least, FDA said that Teva's product--which actually was made by Impax Laboratories and marketed by Teva--was sufficiently equivalent to the branded version. And so many scripts for that version had been dispensed that the patients' problems probably weren't caused by the drug. Their depression just got worse naturally, the agency concluded.
But the agency acknowledged the possibility that the generic might be faulty. It ordered Teva to conduct a bioequivalence test in patients who'd reported problems with the copycat form. Late last year, Teva stopped that study, saying it couldn't find enough patients. Meanwhile, though, FDA had recruited its own patients for its own study comparing Budeprion XL with Wellbutrin XL--and last month, it got the results.
The study found that the generic really didn't release the active ingredient at the same rate and extent. So, FDA now says (read here), Teva's generic isn't therapeutically equivalent to the brand after all. And at FDA's behest, Teva is pulling its version off the U.S. market.
FDA also ordered other generic makers who make their own versions of Wellbutrin XL--Anchen, Activis, Watson Pharmaceuticals and Mylan to conduct their own bioequivalence studies, with data available by March 2013.
So, what does this turnabout by FDA mean? For one thing, it could give branded Wellbutrin XL, now sold by Valeant Pharmaceuticals, a sales boost, particularly if the other generics show bioequivalence problems. It might also lend credence to complaints about other generics; the People's Pharmacy, which publicized the Wellbutrin XL complaints, has also raised questions about generic versions of Toprol XL, the blood pressure medicine, and Keppra, the seizure drug.
It could also prompt a re-examination of FDA's generic approval standards. Some specialists have already suggested that the agency's bioequivalence range is too wide, especially for patients with certain conditions, such as epilepsy and heart arrhythmias