The rise of bio- and nano-technology in the last decades has led to the emergence of a new and unique type of medicine known as non-biological complex drugs (NBCDs). This book illustrates the challenges associated with NBCD development, as well as the complexity of assessing the effects of manufacturing changes on innovator and follow-on batches of NBCDs. It also touches upon proven marketing authorization requirements for biosimilars that could be effective in evaluating follow-on NBCDs, including a demonstration of control over the manufacturing process and a need for detailed physico-chemical characterization and (pre)clinical tests. This book is meant to be used for years to come as a standard reference work for the development of NBCDs. Moreover, this book aims to stimulate discussions and further our thinking to ensure that decisions regarding the approval of complex drugs are made with relevant scientific data on the table.