the generic and brand name versions are exactly the same.
In the U.S. for approval of its generic product, the generic manufacturer must show in a bioequivalency study that the amount of active ingredient delivered from the generic product to the test subjects' bloodstreams is, on average, 80 - 125% of the amount delivered from the brand name drug. Meeting this standard allows the FDA to approve the generic product as a "therapeutic equivalent" that is considered "safe and efficacious."