United States of America
INTRODUCTION All prescription and over-the-counter generic drugs marketed in the United States must meet standards established by the U.S. Food and Drug Administration (FDA). In approving a new generic drug for marketing, the FDA concludes that the generic product is therapeutically equivalent to its corresponding reference product (usually the innovator product, but sometimes another generic product if the innovator product was withdrawn). The FDA believes that therapeutically equivalent drug products can be substituted with the full expectation that both products will produce the same clinical response (1). A generic drug is approved by the FDA if it is (i) pharmaceutically equivalent to an approved safe and effective reference product in that it (a) contains identical amounts of the same active drug ingredient in the same dosage form and route of administration, and (b) meets compendial or other applicable standards of strength, quality, purity, and identify; (ii) bioequivalent to the reference product in that it (a) does not present a known or potential bioequivalence problem, and it meets an acceptable in vitro standard (usually dissolution testing), or (b) if it does present such a known or potential problem, it is shown to meet an appropriate bioequivalence standard; (iii) adequately labeled; and (iv) manufactured in compliance with current good manufacturing practice regulations (1). It is important to note that the regulatory oversight of generic drug chemistry, manufacturing, and controls is identical to that imposed upon innovator drug products (2).