What is a generic drug?
Most prescription drugs have two names: a "generic" name that identifies the active chemical
ingredient, and a "brand" name that is used for advertising purposes. For example, acetaminophen is a
generic name and Tylenol« is a
brand name for acetaminophen.
Generally, new drugs are patent-protected for 20 years from the time of discovery. During this period, only the patent-protected product can be sold. These products are promoted to physicians, pharmacists and other healthcare professionals using a brand name.
When the patent on a brand-name drug expires, the Food and Drug Administration (FDA) allows other companies to manufacture equivalent versions of the original product. These products, which must receive FDA approval prior to marketing, are usually sold using the "generic" name which identifies the active ingredient.
Generic drugs must contain the same active ingredients as their brand-name counterpart; and be identical in strength, dosage form (tablet, liquid, etc.), and route of administration (taken by mouth, injection, etc.) Manufacturers must also prove that the generic product will supply the same amount of the active ingredient in the body, at the same rate, as the brand-name drug.
If you're looking for more specific answers to specific questions, ask a Walgreens pharmacist here.