A brand name drug has a patent, which lasts 15 years. This prevents anyone else from marketing the product until the patent expires. Once the patent expires, any company who is approved by the FDA can begin to market the product as a generic drug. The active ingredients in these medications are exactly the same as their brand name counterpart, although the inactive ingredients and fillers do not have to be the same. If you have a question or concern about whether to use a particular generic, contact your doctor.