Due to rapid scientific progress, biotechnologically produced drugs are becoming increasingly important. Biologically active substances are mostly complex and often glycosylated proteins produced in living organisms (usually cells). Therefore, they naturally exhibit a certain batch-to-batch variability. In contrast to classical small-molecule and synthetically produced drugs, biological substances are not defined by their molecular structure alone, but are further characterized by their manufacturing process. The development and approval of biological drugs is therefore strictly regulated in order to guarantee consistent quality, safety and efficacy.

In addition to fully documented marketing authorisation applications, Art. 24 b (5) AMG and Art. 10 (4) of Directive 2001/83/EC provide a possibility to authorise biological medicinal products which, similar to generics, can refer to a reference medicinal product. In contrast to generics, however, these biological medicinal products cannot be assumed to be identical to the reference medicinal product due to the complexity of the active substances and the inherent variability already described. Therefore, they are considered biotechnologically similar. In order to ensure the efficacy and safety of these so-called "biosimilars", the applicant needs to demonstrate that observed deviations from the reference medicinal product are minimal and do not influence efficacy or safety. In order to prove biosimilarity with the reference medicinal product, extensive comparative analytical and often also clinical studies are required.
In addition to the comparative data described above, administrative data, as well as pharmaceutical quality data and summary expert reports usually required for any new medicinal product, must be submitted.