Investigational drugs for allergic rhinitis.

Allergic rhinitis (AR) is a high-prevalence disease, triggered by an IgE-mediated reaction, and sustained by a complex inflammatory network of cells, mediators, and cytokines. When the exposure to allergens persists, the inflammatory process becomes chronic. The current therapeutic strategy is based on allergen avoidance when possible, drugs and allergen immunotherapy. The main drugs are oral and topical antihistamines and nasal steroids. They are overall effective in controlling symptoms, but do not modify the immune background that leads to allergic inflammation. In addition, safety concerns may be present, especially for prolonged treatments. Thus, efforts are currently made to improve the existing molecules and to develop new drugs, in order to achieve greater clinical efficacy with a better tolerability. Also, attempts are made to selectively block relevant signal pathways of the allergic reaction by means of specific anti-mediators. Specific immunotherapy, in addition to the clinical effect, is capable of modifying the Th2-biased immune response. Thus, an intense research activity is presently ongoing with the aim of improving the characteristics and modes of action of this treatment.