Pharmaceutical equivalents, by definition, are drug products with the same active ingredient in the same quantities, encapsulated in identical dosage forms, and intended for the same administration routes. These pharmaceutical equivalents are deemed bioequivalent if the bioavailability of the active entity in the drug preparations is similar. Moreover, pharmaceutical equivalents demonstrating bioequivalence are also regarded as therapeutically equivalent. This means that when used as directed, they yield the same clinical effect and safety profile.

A key determinant of clinical effectiveness is that the peak concentration of the drug, and the time taken to achieve this peak concentration, must fall within an acceptable range. However, there can be variations in the bioavailability of a drug's dosage form. These discrepancies might occur between different manufacturers or even among different batches from the same manufacturer. The reason behind this is often inadequate control over the drug's physical properties during its formulation and manufacturing. This lack of control can affect how the drug disintegrates and dissolves, impacting its bioavailability. Finally, for a generic drug to gain approval, its bioequivalence profile must align closely with that of the reference product.