The U.S. Food and Drug Administration said that tests of Budeprion XL 300 milligrams showed that the drug is not as effective as a comparable dose of GlaxoSmithKline‘s (NYSE:GSK) Wellbutrin, which lost its patent protection in 2006, the Wall Street Journal noted.
Bupropion hydrochloride is the active ingredient in both the brand name and generic versions of Wellbutrin.
After tests in 24 adults, the agency noted that the 300 milligram dose of Budeprion XL failed to release bupropion into test subjects’ blood at the same pace as Wellbutrin.
Budeprion XL is produced by Impax Laboratories (NASDAQ:IPXL), which has stopped shipping the generic drug. No safety issues have been raised by the tests.
The 150 milligram dose of Budeprion XL is not involved and will continue to be marketed and sold in the U.S. The FDA noted that generic versions of Wellbutrin produced by other manufacturers were not affected.
Shares of Teva fell just under 1% in Thursday morning trading, while Impax shares moved fractionally lower and GlaxoSmithKline shares rose about 1%.