New methods for the characterisation of biopharmaceuticals: conjugate vaccines against Haemophilus influenzae type b.

Modern physicochemical methods allow biological pharmaceuticals, particularly those arising from recombinant DNA technology, to be characterised with a degree of precision not previously possible. These techniques, which tell us what a material is (rather than what it does) provide an approach complementary to traditional bioassays for the control of biological pharmaceuticals. As we come to understand the mechanisms by which structural variation modulates the various biological activities of a product, structure-based assays will be able to replace biological identity and potency assays, although replacement of safety tests to find trace impurities (such as endotoxin) may be more difficult.