Generic Drug Definition

Generic Drug is a drug that has bioequivalence and therapeutic equivalence to its innovator drug (the first drug to receive approval for use). Generic drugs became significant in the health-care industry in the 1970s when manufacturing requirements and procedures became standardized and patents began to expire on innovator drugs, converging factors that opened the market for competition within the pharmaceutical industry.

generic drug

Most generic drugs are significantly less expensive than their innovator counterparts, and most states have laws allowing pharmacies to substitute generic drugs when filling prescriptions unless the prescribing provider specifies otherwise. The intent behind such laws is to provide consumers with cost-effective alternatives for prescription drugs. Generic products are also available for many over-the-counter (otc) drugs, allowing consumers to choose either generic or trade name products.

The US Food and Drug Administration (FDA), the federal regulatory agency that approves drugs for use in the United States, establishes the criteria for potency, purity, consistency, and efficacy all drugs must meet. These criteria are the same for innovator and generic drugs. Generic drugs may also have trade names, which manufacturers often use to establish brand recognition and brand loyalty for marketing purposes. For example, Elavil and Endep are trade names for amitriptyline, a commonly prescribed tricyclic antidepressant. The manufacturer of an innovator drug may also produce and market generic versions of the drug when the innovator drug’s patent expires.

In nearly all circumstances a person may take any manufacturer’s product, generic or innovator drug, and experience the same therapeutic effects. The only exception is with narrow therapeutic index (nti) drugs, in which the margin between the therapeutic dose and the toxic dose is exceedingly small. People who take NTI drugs should always take the same product, whether the innovator drug or a generic drug. Variations in the drug’s inactive ingredients can affect how the body absorbs the drug, which can have therapeutic significance with NTI drugs.

In its electronic document the orange book, the FDA maintains a list of newly approved generic drugs, updated each month, and a list of all generic drugs available in the United States. The Orange Book is available at the FDA’s Web site (


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