Ebastine in context. Introduction

The allergic reaction to a specific antigen is characterised by a series of complex immunological processes consisting of an early specific immune response and a late inflammatory reaction. The release of active substances (principally histamine) from cytoplasmic granules of mast cells and basophils in response to antigen challenge is responsible for many of the symptoms observed in the early phase of the allergic reaction. The late phase inflammatory reaction caused by the recruitment of inflammatory cells (mainly eosinophils) to the area of initial antigen challenge and the consequent release of soluble factors result in amplification and prolongation of allergic symptoms. Antihistamines are the most widely used drugs for the treatment of allergic conditions. These agents act on both the early immune response (by blocking the action of histamine at the H1 receptor) and also demonstrate anti-inflammatory effects. Second generation antihistamines are free of the sedative and anticholinergic effects characteristic of the first generation agents. Ebastine, the focus of this supplement, is a new second generation agent that has shown antihistamine activity in preclinical studies and clinical efficacy in providing relief from symptoms in patients with allergic disorders.