Generic Drug Found To Be Therapeutically Unequal to Brand Name Counterpart

In what many believe to be an uncharacteristic move by the U.S. Food and Drug Administration (FDA), regulatory officials have declared that generic drugs do not necessarily represent the equivalent of their name brand counterparts. Subsequently, a recent test revealed that Budeprion 300 mg XL is not therapeutically equivalent to its name brand predecessor Wellbutrin XL. In response to these findings, Teva Pharmaceuticals was prompted to stop shipping Budeprion 300 mg XL and to remove it from U.S. shelves.

As a worldwide leader in the pharmaceutical industry, GlaxoSmithKline has been responsible for the distribution of healthcare products since the beginning of the eighteenth century. Currently headquartered in the UK, the global organization is responsible for the development and distribution of Wellbutrin XL. The immensely popular antidepressant has been indicated to assist in the treatment of depression and seasonal affective disorder (SAD) since its release in 2003.

Following the expiration of their patent, GSK witnessed several generic variations of Wellbutrin XL begin to saturate the U.S. market. Of those generic variations, Budeprion XL 300 mg (bupropion hydrochloride extended-release tablets), was the most popular. Manufactured by Impax Laboratories, Inc., and marketed by Teva Pharmaceuticals USA, Inc., Budeprion XL 300 mg was indicated for the same treatments as Wellbutrin XL.

Budeprion XL 300 mg was approved in December 2006. Soon after, the FDA was made aware of reports in which patients who were switched from Wellbutrin XL 300 mg to its generic counterparts began experiencing reduced efficacy. Upon further review of the reports, officials at the FDA concluded that the complaints appeared to be linked to the Impax/Teva product. The FDA therefore asked Impax/Teva to conduct a study directly on its 300 mg extended-release product to compare its bioequivalence to Wellbutrin XL 300 mg. FDA asked that the study include patients who had reported lack of efficacy after switching from Wellbutrin XL 300 mg to Budeprion XL 300 mg. Impax/Teva began the study, but terminated it in late 2011, reporting that, despite efforts to enroll patients, Impax/Teva was unable to recruit a significant number of affected patients to generate the necessary data.

In 2010, in light of the public health interest in obtaining bioequivalence data, the FDA decided to conduct a study comparing Budeprion XL 300 mg to Wellbutrin XL 300 mg. This clinical trial was conducted in 24 healthy adult volunteers and was designed to measure both the rate and the extent of release of bupropion into the blood. According to an FDA Drug Safety and Availability Report, Budeprion XL 300 mg tablets fail to release bupropion into the blood at the same rate and to the same extent as Wellbutrin XL 300 mg.

Therefore, on October 3, officials at the FDA declared that Budeprion XL 300 mg is not therapeutically equivalent to Wellbutrin XL 300 mg. The FDA has since changed the therapeutic equivalence rating for this product in the Agency’s Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) from AB to BX, signifying that Budeprion XL 300 mg fails to demonstrate therapeutic equivalence to Wellbutrin XL 300 mg.