Abstract

When the bioequivalence (BE) of a generic product to a reference drug is stated, their interchangeability is generally assumed. This implies that the drug products can be readily switched and substituted. However, it is important to distinguish between the conditions of prescribability and switchability when, respectively, a drug is provided to a patient either for the first time in any of its forms or administered by replacing another formulation of the same drug product. These two conditions are statistically characterized by the regulatory models of population and individual BE. These models embrace important principles.