Allergic rhinitis and its pharmacology

The pathophysiology of allergic rhinitis and its drug treatment is reviewed. Special emphasis is placed upon potential new treatments. Allergic rhinitis is characterized by allergen(s), symptoms (sneezing, itching, rhinorrhea, nasal congestion and nasal hypersensitivity), and signs such as invasion of nasal mucosa by inflammatory cells. Such pathological changes are due to inflammatory responses mediated by way of allergen-immunoglobulin E (IgE)-cell complex formation. The complexity of the disease and the multiple pathways involved offer many targets for drug treatment, but to date no single drug is totally effective. This review summarizes the current knowledge of allergic rhinitis, its prevalence, pathophysiology and experimental and clinical treatments. In the search for new drugs, different experimental animal models of allergic rhinitis are required. As a result the models have also been reviewed. Furthermore, particular aspects of the pathophysiology of allergic rhinitis are discussed in greater detail including the immune cells involved in the mediation of the disease, chemical mediators, their actions, and the receptors on which they act. Therapy, particularly that with current drugs, targets many of the known mediators and some of the cellular processes with varying success. Other drugs, for example, vasoconstrictors given to reduce rhinorrhea, provide symptomatic relief by counteracting symptoms. Since the incidence of allergic rhinitis is prevalent and growing in many parts of the world and current treatments are not ideal, it is important to continue to study the pharmacology of this disease as part of a search for better drugs.