A generic drug (generic drugs, short: generics) is a drug which is produced and distributed without patent protection. The generic drug may still have a patent on the formulation but not on the active ingredient.

A generic must contain the same active ingredients as the original formulation. According to the U.S. Food and Drug Administration (FDA), generic drugs are identical or bioequivalent to the brand name counterpart with respect to pharmacokinetic and pharmacodynamic properties. By extension, therefore, generics are identical in dose, strength, route of administration, safety, efficacy, and intended use. In most cases, generic products are available once the patent protections afforded to the original developer have expired. When generic products become available, the market competition often leads to substantially lower prices for both the original brand name product and the generic forms. The time it takes a generic drug to appear on the market varies. In the US, drug patents give twenty years of protection, but they are applied for before clinical trials begin, so the effective life of a drug patent tends to be between seven and twelve years.

Economics

Generic drugs can save patients and insurance companies substantial costs. The principal reason for the relatively low price of generic medicines is that competition increases among producers when drugs no longer are protected by patents. Companies incur fewer costs in creating the generic drug, and are therefore able to maintain profitability at a lower cost to consumers. The costs of these generic drugs are so low that many developing countries can easily afford them. For example Thailand is going to import millions of doses of the generic version of Plavix, a blood-thinning treatment to prevent heart attacks, at a cost of 3 US cents per dose from India, the leading manufacturer of generic drugs.

Generic manufacturers do not incur the cost of drug discovery, and instead are able to reverse-engineer known drug compounds to allow them to manufacture bioequivalent versions. Generic manufacturers also do not bear the burden of proving the safety and efficacy of the drugs through clinical trials, since these trials have already been conducted by the brand name company. (See the Approval and regulation section, below, for more information about the approval process.) It has been estimated that the average cost to brand-name drug companies of discovering and testing a new innovative drug (with a new chemical entity) may be as much as $800 million.

Generic drug companies may also receive the benefit of the previous marketing efforts of the brand-name drug company, including media advertising, presentations by drug representatives, and distribution of free samples. Many of the drugs introduced by generic manufacturers have already been on the market for a decade or more, and may already be well-known to patients and providers (although often under their branded name).