Generic drugs are those that are pharmaceutically equivalent to pre-existing brand-name drugs, also known as a reference listed drug (RLD). The generic drug should consist of the same active ingredients, dosage form, strength, route of administration, and bioequivalence as those listed within the RLD. This means there should be no difference in the rate or extent of the absorption of the active ingredient. While bioequivalence can be achieved through the process of vivo or in vitro testing (or both), all methods used to test bioequivalence should ensure accuracy, sensitivity, and reproducibility.