IMMUNOTHERAPY FOR ALLERGIC RHINITIS

The safety and efficacy of desloratadine for the management of allergic disease

Allergic disease is an increasing problem worldwide. Allergic rhinitis, an inflammatory response to an allergen, affects an estimated 20-40 million people in the US, while chronic idiopathic urticaria is a dermatoallergic condition that affects 0.1-3% of people in the US and Europe. The primary goals of treatment for allergic rhinitis are to reduce symptoms, which include sneezing, rhinorrhoea and nasal congestion, improve quality of life and prevent the sequelae associated with this disease, while the goal for chronic idiopathic urticaria is the rapid and prolonged control of symptoms. Quantitatively, histamine is the most abundant mediator present during an allergic episode - thus, antihistamines (historically called histamine H(1) receptor antagonists, now called H(1) receptor inverse agonists) are a first-line defense against allergic rhinitis and chronic idiopathic urticaria. Although first-generation antihistamines can cause sedation and cognitive impairment, second-generation antihistamines are relatively non-sedating and free of such adverse events owing to their comparative inability to penetrate the blood-brain barrier. Desloratadine is one such second-generation antihistamine and is indicated for the treatment of allergic diseases, including allergic rhinitis and chronic idiopathic urticaria. It has proven efficacy against the symptoms associated with seasonal and perennial allergic rhinitis, including nasal congestion, and chronic idiopathic urticaria. As a result, it has been shown to improve patients' quality of life. The safety and efficacy profiles of desloratadine are well established, and published postmarketing analyses have assessed >54 000 patients. Although earlier second-generation antihistamines have been associated with cardiovascular adverse effects, desloratadine has been shown to be safe and well tolerated at nine times the recommended dose. In addition, it has been shown to not interact with concomitantly administered drugs and food. Overall, current data indicate that desloratadine is a safe and effective treatment for allergic diseases.

Allergic rhinitis: impact of the disease and considerations for management

AR is a common condition affecting individuals of all ages. Those afflicted with AR often suffer from associated inflammatory conditions of the mucosa,such as AC, rhinosinusitis, asthma, otitis media with effusion, and other atopic conditions, such as eczema and food allergies. Lack of treatment or treatment with suboptimal therapy may result in reduced quality of life and compromise productivity at work or school. Although environmental controls may prove difficult to implement, and not all controls appear adequately to mitigate symptoms of AR, they continue to represent a foundation for treatment. Many different classes of medications are now available, and they have been shown to be effective and safe in a large number of well-designed, double-blind, placebo-controlled clinical trials. Some of the over-the-counter medi-cations have been associated with increased sedation, potentially leading to accidents and fatalities at work or while operating complex machinery, such as automobiles. Only immunotherapy with increasing doses of individually targeted allergens results in sustained changes in the immune system. Although anti-IgE is probably only the first successful immunomodulator commercially available to treat AR, monoclonal antibodies will remain too costly, at least in the near future, to find their way into routine AR treatment.

Allergic rhinitis: an update

Allergic rhinitis is extremely common and a global health problem. One study has quoted a prevalence of 16% and, as with asthma, it seems to be increasing. This increase and association with asthma have raised concerns about appropriate treatment. Fortunately, with new knowledge of the pathophysioLogic mechanisms, newer and better treatment strategies have been developed. This short review of allergic rhinitis highlights its prevalence, pathophysiology, clinical presentation, investigation and management. A new classification and recommendations by the World Health Organization's guidelines 'Allergic Rhinitis and its Impact on Asthma' are also discussed.

Etiopathogenesis and Management of Perennial Allergic Rhinitis

Perennial allergic rhinitis is an inflammatory disorder characterized by symptoms of nasal congestion, rhinorrhea, sneezing, and itching. The prevalence of allergic rhinitis is quite common and affects 20% or more of various populations. Some patients with allergic rhinitis are symptomatic only during the pollen season, while many others are allergic to multiple allergens including indoor allergens such as house dust mites, animal dander, cockroaches, and fungi, which lead to perennial symptoms. Immunoglobulin (Ig)-E is the proximate cause of perennial allergic rhinitis. Circulating IgE antibodies bind to the high affinity IgE receptor on mast cells and basophils. IgE antibodies, bound to the receptors crosslinked by allergen, initiate the secretion of inflammatory mediators including histamine, leukotrienes, and cytokines. These mediators can induce both acute and chronic changes that result in symptoms of allergy. Many therapies are approved for the treatment of allergic rhinitis including intranasal corticosteroids, antihistamines with or without decongestants, and nasal cromolyn sodium (sodium cromoglicate). Allergen avoidance is the mainstay of therapy for many patients but is not always practical. For those patients who have not responded to appropriate medications, allergen specific immunotherapy may also be effective.A number of studies with omalizumab have shown that it is effective in the treatment of seasonal allergic rhinitis induced by pollen such as ragweed and birch pollen. Omalizumab is a molecularly cloned humanized monoclonal antibody inhibiting human IgE. It binds specifically to the region of the IgE molecule that binds to the IgE receptor on the mast cell or basophils. Because omalizumab cannot bind IgE molecules that are already bound to the surface receptors on mast cells and basophils, it does not stimulate secretion of mediators from these cells. Omalizumab does not appear to stimulate an immune response against itself. It rapidly reduces free serum IgE levels by over 95% when administered at therapeutic doses and also results in the reduction of IgE receptors on mast cells and basophils. The combined effects of reduction of both free IgE in serum and the receptor density on the mast cells or basophils results in decreased allergen-stimulated mediator release. Preliminary studies in the treatment of perennial allergic rhinitis supports omalizumab's efficacy and safety. The compound has been well tolerated. Aside from urticarial reactions, adverse effects appear to be minimal. Omalizumab is the first of several new immune-based specifically targeted molecules that may prove to be extremely valuable in the treatment of perennial allergic rhinitis, as it is often unresponsive to traditional therapies.