Abstract

When the patent of a biological drug expires, alternative, biosimilar products are often developed. They are expected to have highly similar clinical effects with the original drug. Still, even after the approval of the biosimilarity of two drug products, their interchangeability within subjects remains to be determined. Regulatory authorities in the United States, Canada and the European Union follow differing approaches to the approval of interchangeability. The disbursement of funds for drugs and, consequently, the decisions for interchangeability are generally left for the states, provinces and constituent states. This leads to widely diverging practices and, in the United States, possible legal complications. Statistical approaches are presented for the determination of the switching, alternation and interchangeability of biological products and for the design of the corresponding studies.