Introduction

Specialty drug products discussed in this textbook are defined as nonorally absorbed drug products for which pharmaceutical equivalence is not easily demonstrated and in many instances bioequivalence cannot be determined using only the measurement of drug concentrations in plasma. For many specialty drug products, the demonstration of pharmaceutical equivalence and bioequivalence is more difficult compared to solid oral drug products intended for systemic activity, consequently, the requirements and procedures for bioequivalence have have not been agreed upon by both the scientific and regulatory communities. When the usual assessments of bioequivalence and pharmaceutical equivalence are not applicable, scientific and regulatory challenges become barriers to the development and approval of generic drug products. Moreover, legal challenges often arise when there is no general agreement on these issues.