On October 3, 2012, the FDA announced its finding that the Impax Bupropion Extended-Release Tablets, 300mg, distributed by Teva, was found to be bio-inequivalent to the reference listed drug (RLD) Welbutrin XL 300 mg Tablets. The firms withdrew their product from the market.
A little over a year later, on October 10, 2013, FDA announced the results of the bioequivalence studies required by four additional companies, Actavis, Mylan, Par Pharmaceuticals, and Watson conducted to confirm a finding of bioequivalence of their approved 300 mg Bupropion Extended-Release Tablets. The studies submitted by Actavis, Mylan, and Par Pharmaceuticals confirmed that their products are bioequivalent to Welbutrin XL 300 mg Tablets. However, the study performed by Watson failed to confirm bioequivalence to the RLD, and the firm has agreed to voluntarily withdraw its product from the distribution chain