Copy cat versions of well known and widely used brand name products that are less expensive are known a generic drugs. In some cases such as foods and other household products the term generic implies that you will pay less but you could be receiving a product of lower than standard quality or effectiveness. With pharmaceuticals, this is generally not the case. When drugs are first discovered they are given a chemical or code name that is developed for easy reference among researches. When the drug is approved by the Food and Drug Administration it is given tow additional names. One of these names is its generic name, while the other is known as its trade or brand name.

When the drug is written about by researchers, government or doctors the generic name is used. This is because it refers to the drug itself and not the name of a particular company's brand name for the drug. But when the drug is used for a written perscription, in most cases, the trade name is used. This is because generic names are often more complicated and harder to remember than trade names. Often the generic names are a kind of shorthand for the drug's chemical formula, name or structure. On the other hand, trade names are easy to remember and are often unique. In most cases the trade name will indicate a particular characteristic of the drug such as Lopressor which lowers blood pressure.

Trade names and generic names are regulated by authorities to insure that they are unique and cannot be mistaken for other drugs. If the names or too similar to those of another drug it could lead to mistakes in drug prescribing or dispensing. When a company in the United States develope a new drug they are granted various patents for the way it is used, made and the drug itself. This patent is good for 17 years, with 10 years elapsing prior to approval of the drug for use. When this patent expires, other companies may sell a generic version of the drug at a much lower price. In most cases generic drugs can be assumed to work as well as the brand name drug. Like the brand name drug the generic version must be approved by the Food and Drug Administration before it is distributed.

The development and manufacturing of a perscription drug can follow many different routes to produce a drug that is safe and effective. Once a company decides to produce a generic version they will use active ingredients that are identical to those of the original drug but they may use different inactive ingredients. The inactive ingredients are added to specific reasons such as to provide bulk, keep a pill from crumbling, help a tablet dissolve in the stomach or intestines or to give it a pleasant taste or color. These ingredients are generally harmless substances that do not affect the body. But in a few cases these substances can cause unusual and severe allergic reactions. A generic drug will differ from its trade name counter part in size, color and shape for legal reasons.

The bio-equivalence of different versions of a drug can vary as much a 20 percent without any noticeable difference in the effectiveness of the drug. This difference is not just found in generic brands but can also be found in different batches of a brand name drug. With generic and brand name drugs which are taken by mouth this difference is much smaller.