How do we assure the quality of biological medicines?

Biological medicines are a rapidly growing area of interest to many pharmaceutical companies, large and small. Under a broad definition they include not only modern high-tech products, such as monoclonal antibodies, enzymes and cytokines, but also older well-established products, such as vaccines and blood products. Despite a long history of standardisation and control of biological medicines, and an elaborate system of licensing and regulation, problems still occur because of their complexity. This review includes historical and regulatory background and three examples of problems seen with biotherapeutics: streptokinase, heparin and TGN1412.