Just as good?

By the time Jillian Bealer turned to the Internet for information early this year, she found a chorus of complaints from Wellbutrin XL users who had switched to a new generic made by Teva. Their disappointment in the generic's performance began showing up on drug- and depression-related Internet chat sites in March 2007, about two months after Teva's generic hit the market.

More than 300 of those patients had sent anguished letters and e-mails to Joe and Teresa Graedon, the founders of a respected multimedia clearinghouse that dispenses independent advice on drugs and dietary supplements. (The Graedons' syndicated column, People's Pharmacy, runs in this and other newspapers.)

These consumers reported increased anxiety and irritability, headaches, nausea and insomnia since switching to the generic. Many reported a return of their previously controlled depressive symptoms.

By summer 2007, the Graedons had collected enough letters from readers to alert the FDA and to ask an independent testing and certification lab, ConsumerLab.com, to compare the new Wellbutrin generics against their original counterparts and assess claims of equal performance.

The results, confirmed by a second test lab and released last fall by ConsumerLab.com, raised questions about at least one version of the generic copies -- a 300-milligram dose of bupropion marketed by Teva -- as well as the FDA process by which a proposed generic's equivalence to a pioneer drug is established.

"We were shocked when we got the results" comparing the 300-milligram tablet of Wellbutrin XL -- the most frequently prescribed dose of the product -- and Teva's generic, said Tod Cooperman, president of ConsumerLab.com. The rate at which the two pills dissolved when in a medium mimicking the human digestive system "was very different," he said.

Both products released the same amount of bupropion hydrochloride into the solution over 16 hours, but the generic pumped out its active ingredient much faster than did the branded product: In the first two hours, the generic released a third of its active ingredient -- four times as much as its brand counterpart. At four hours, the generic had released almost half of its medicine, the brand-name about a quarter.

The difference might well explain why consumers accustomed to taking Wellbutrin XL would feel different when taking Teva's generic, marketed as Budeprion XL, said Cooperman. With a more rapid release rate, the concentration of generic bupropion in the blood will rise quickly, but may also fall lower late in the 24-hour cycle than would be the case with the branded Wellbutrin XL.