Allergoids for allergy treatment.

Background Chemically modified allergen extracts, known as allergoids, are commonly used for treating allergic patients. In general terms, the concept of allergoids implies allergen extracts with a reduction of their allergenicity maintaining their immunogenicity. Different methods to obtain allergoids have been developed in the past years, opening attractive lines of research. Objective To review the different approaches to allergoid development as well as their characterization, mechanism of action and efficacy and safety issues. Methods A revision and analysis of the different types of allergoids has been performed, with special attention to patents submitted and granted in the last years. Additionally, updated information about the mechanism of action and clinical evidence and safety of allergoids has been discussed. Results Principally, allergoids are obtained by the polymerization of native allergen extracts with aldehydes, including formaldehyde or glutaraldehyde. However, recent patents and publications about different chemical modifications have been presented, as well as about the use of new adjuvants with allergoids. Regarding the characterization, allergoids require more sophisticated analytical methods than native extracts, as a consequence of their properties and characteristics. Conclusion In the last years, the partial understanding of the mechanism of action and the generation of clinical evidence of different types of allergoids, linked to their excellent safety profile and their convenience for a quick build up phase, have made of allergoids an excellent product for allergy treatment.