Antiallergic Agents
Authors: Höfgen Norbert , Beckh Sonja , Szelenyi Istvan , Bölcskei Pal L. 
Published: April 2006

Allergic reactions cause a number of acute and chronic diseases. Theantigenorallergencausing the allergic reaction is usually a protein, a polysaccharide, or a low molecular mass compound (hapten) bound to an endogenous protein. Antigens induce the synthesis of antibodies, which are serum proteins, referred to as immunoglobulins (Igs). Antigen cross‐linking of the IgE molecules leads to cellular responses involving release of preformed mediators, e.g., histamine.Antihistaminesor histamine H1receptor antagonists are used in the treatment of allergic diseases. In contrast to the first‐generation or classical antihistamines the second‐generation antihistamines do not have the side effects sedation, fatigue, and drowsiness. Mast cells are the predominant storage site for histamine in most tissues. Cromolyn sodium or disodium cromoglycate (DSCG) probably acts on certain types of chloride channels expressed in mast cells and sensory nerves.

Allergen immunotherapy is a well established and accepted treatment of allergic diseases. Immunogenic tolerance is achieved by applying gradually increasing quantities of an allergen vaccine to the sensitized patient. Allergen preparations derive from reference standards containing defined amounts of relevant allergens. For efficient and well‐tolerated therapy extracts are physically or chemically modified or conjugated. Recombinant DNA technology offers a new standard of qualitiy by selecting the disease causing major allergens.

The development of an anti‐IgE antibody (omalizumab, Xolair™) offers a unique and novel treatment not only for therapeutic but also for preventive applications in IgE‐mediated diseases. Omalizumab is a DNA‐derived monoclonal humanized antibody which is well tolerated by the immune system. Omalizumab binds in form of complexes to free IgE in the serum and interacts with any kind of IgE, but not with other immunoglobulines. Omalizumab leads to a downregulation of IgE receptors on mast cells and tissue cells in target organs. The substance showed immunomodulatory effects on dendritic cells and reduced significantly the number of eosinophils. Effects of treatment on allergic rhinitis and asthma have been evaluated in several studies.

The article contains sections titled:1.Introduction2.Antihistamines2.1.First Generation Antihistamines2.1.1.Ethylenediamines2.1.2.Ethanolamine Derivatives2.1.3.Alkylamines2.1.4.Piperazines2.1.5.Piperidines2.1.6.Phenothiazines2.1.7.Other Tricyclic Systems2.2.Second‐Generation Antihistamines2.2.1.Ethanolamines2.2.2.Alkylamines2.2.3.Piperazines2.2.4.Piperidines2.2.5.Phthalazinones2.2.6.Others2.2.7.Combinations of Antihistamines and Sympathomimetic Agents2.3.Inhibitors of Histamine Synthesis3.Mast Cell Stabilizing Agents4.Allergen Preparations for Desensitization4.1.Properties of Allergens4.2.Raw Materials4.3.Allergen Standardization4.4.Allergen Vaccines for Immunotherapy4.5.Storage4.6.Uses4.6.1.Diagnostic Use4.6.2.Therapeutic Use‐Immunotherapy4.6.3.Legal Aspects, Quality Requirements, and Safety5.Anti‐IgE‐Omalizumab5.1.IgE and its Role for the Allergic Response5.2.IgE‐Mediated Allergic Diseases5.3.Properties of Omalizumab5.3.1.Chemistry and Production of Omalizumab5.3.2.Pharmacology and Effect of Omalizumab5.3.3.Pharmacokinetics5.4.Indication for the Teatment with Omalizumab, Guidelines for Use5.5.Application, Dosage, Costs5.6.Side Effects5.7.Legal Aspects, Safety5.8.Possible Applications in the Future6.Acknowledgement