Antiallergic Agents

Abstract

Allergic reactions cause a number of acute and chronic diseases. The antigen or allergen causing 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. Antihistamines or histamine H 1 receptor 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. Introduction 2. Antihistamines 2.1. First Generation Antihistamines 2.1.1. Ethylenediamines 2.1.2. Ethanolamine Derivatives 2.1.3. Alkylamines 2.1.4. Piperazines 2.1.5. Piperidines 2.1.6. Phenothiazines 2.1.7. Other Tricyclic Systems 2.2. Second‐Generation Antihistamines 2.2.1. Ethanolamines 2.2.2. Alkylamines 2.2.3. Piperazines 2.2.4. Piperidines 2.2.5. Phthalazinones 2.2.6. Others 2.2.7. Combinations of Antihistamines and Sympathomimetic Agents 2.3. Inhibitors of Histamine Synthesis 3. Mast Cell Stabilizing Agents 4. Allergen Preparations for Desensitization 4.1. Properties of Allergens 4.2. Raw Materials 4.3. Allergen Standardization 4.4. Allergen Vaccines for Immunotherapy 4.5. Storage 4.6. Uses 4.6.1. Diagnostic Use 4.6.2. Therapeutic Use‐Immunotherapy 4.6.3. Legal Aspects, Quality Requirements, and Safety 5. Anti‐IgE‐Omalizumab 5.1. IgE and its Role for the Allergic Response 5.2. IgE‐Mediated Allergic Diseases 5.3. Properties of Omalizumab 5.3.1. Chemistry and Production of Omalizumab 5.3.2. Pharmacology and Effect of Omalizumab 5.3.3. Pharmacokinetics 5.4. Indication for the Teatment with Omalizumab, Guidelines for Use 5.5. Application, Dosage, Costs 5.6. Side Effects 5.7. Legal Aspects, Safety 5.8. Possible Applications in the Future 6. Acknowledgement

4a′-Hydroxy-3′,3′,5,6′,6′,7-hexamethyl-3′,4′,4a′,6′,7′,9a′-hexahydrospiro[indole-3,9′-xanthene]-1′,2,8′(1H,2′H,5′H)-trione

“…Xanthenes are very important compounds with tremendous biological applications, such as antispasmodic [19], antiparkinsonian [20], and antipsychotic ones [20]. They are also used in the treatment of urinary incontinence [21] and bronchitis [22].…”