ABSTRACT
The standardization of allergen extracts is the process that assures the quality and batch-to-batch consistency of allergen products intended for both diagnosis and treatment. This chapter describes this process in Europe, since pioneer immunochemical methods were developed in the 1970s and 1980s, as well as the current quality requirements governing these kinds of products in Europe. Allergen extracts are complex biological mixtures derived from allergen-containing source materials (e.g., pollens, mite and animal epidermal derivatives) which are subjected to a natural variation. In addition, important differences exist in Europe in the preparation of products used for allergy vaccination (e.g., aqueous formulation versus alum-adsorbed vaccines of either native or chemically modified allergens). This explains the difficulty of the regulatory requirements governing allergens and the need for specific monographs covering the different steps (source material, drug substance, and drug product) involved in the manufacture of these products.
