Antihistamines in urticaria

Urticaria is one of the most common and, in its chronic course, excruciatin g dermato-allergic diseases. Apart from the dermatological diagnosis, the i dentification and evaluation of causal triggering factors is of utmost impo rtance. Here a 'three-step guideline' (according to Ring and Przybilla) has gained acceptance, ranging from a general basic examination via an intensi ve investigation until oral provocation tests for food allergy and oral pro vocation tests for idiosyncrasy (OPTI) against food additives. Apart from true IgE-mediated allergies, pseudo-allergic reactions against f ood additives as well as food contents represent a major problem in chronic urticaria. Recently gastric mucosal colonization with Helicobacter pylori as the trigger of chronic urticaria has received attention. New pathophysio logical concepts describe autoantibodies that are directed either against I gE or against the high-affinity IgE-receptor on the surface of mast cells a nd basophil leucocytes. In the intradermal test with autologous serum posit ive wheal and flare reactions can be observed (Greaves' test). In many patients with chronic urticaria considerable psychosomatic involvem ent is also observed. Histamine is one of the major mediators of most forms of urticaria although in some cases, especially physical urticaria, other mediators seem to play a role. Therefore antihistamines, and mainly H-1 antihistamines, are the m ainstay of antiurticaria therapy. Some studies have shown a benefit of combined H-1- and H-2-antagonist treat ment in special forms of urticaria namely urticaria factitia. Similarily pr etreatment with combined H-1 and H-2 antagonists has been proven to reduce effectively the frequency of pseudo-allergic reaction to some histamine-rel easing drugs used in radiology or surgery. More than 50 years after the first introduction of an antihistamine into al lergy therapy, antihistamines still represent modern and exciting agents co ntributing to the continuous improvement of antiallergic therapy. Antihistamine therapy can be performed with either the classical or second generation antihistamines. Classical antihistamines are connected with cons iderable side-effects especially sedation and anticholinergic effects. New non-sedating antihistamines have been developed that do not cross the blood -brain barrier. The efficacy of mizolastine, a new non-sedating H-1 antagonist, has been ev aluated in several placebo-controlled and comparative clinical trials. Over all, mizolastine 10 mg/day was found to be significantly more effective tha n placebo and as effective as other second generation antihistamine drugs i n the management of patients with chronic urticaria, with a rapid and susta ined action.