The lawsuit was brought against Teva Pharmaceutical Industries Ltd. (TEVA) and Impax Laboratories Inc. (IPXL) concerning their generic formulation of anti-depressant Wellbutrin XL marketed as Budeprion XL.

The lawsuit claims that Budeprion XL contains an inferior delivery mechanism to that contained in Wellbutrin XL which results in a much more rapid, and potentially harmful, release of Budeprion XL's key ingredient to end-use consumers. According to the suit, the result is that Budeprion XL is less effective in treating depression and, indeed, is much more likely to cause certain dangerous side effects, as compared to Wellbutrin XL.

The U.S. Food and Drug Administration has previously studied reports of side effects from users of generic Wellbutrin, but deemed the drug safe. Still, some doctors say their patients don't do well when they switch to the branded version and expressed hope the FDA would continue its investigation.

The FDA has said it may request a special clinical trial involving generic Wellbutrin, but it's revealed no additional details since September.