How is a "generic drug" defined?

A generic drug is defined as a medication that is equivalent to a brand-name drug in terms of dosage form, strength, route of administration, quality, performance characteristics, and intended use. This equivalence means that generic drugs are considered to be bioequivalent to their brand-name counterparts, meaning they perform in the same manner in the body.

Generic drugs contain the same active ingredients as the brand-name drug and are typically marketed after the expiration of the original drug's patent. Because they do not have the same R&D costs associated with the development of new drugs, generic drugs are usually sold at a lower price than their brand-name equivalents, making them more accessible to patients.

The other options do not accurately capture the definition of a generic drug. Patented drugs are not generic, as they are still under exclusive branding. While many generic drugs require prescriptions, not all do, particularly in the case of over-the-counter (OTC) generics. Lastly, stating that a drug has no side effects is misleading, as all medications can have potential side effects, whether they are generic or brand-name.