A Multicentre, Placebo Controlled, Double-Blind Study for Evaluation of Safety and Efficacy of Preseasonal Specific Immunotherapy With an Allergoid Preparation of an Extract of a 6 Grass Pollen Mixture in Patients With Clinically Relevant Grass Pollen Sensitivity

Pollen allergoids are prepared by chemical modification of partially purified native allergen aqueous extracts that have been depleted of components with a molecular mass of less than 5000 Daltons by diafiltration. Clinical studies have shown a good tolerance of aqueous grass, ragweed and tree pollen allergoids in comparison with allergen preparations. Adsorption of pollen allergoids onto aluminium hydroxide suspensions results in depot preparations which have been investigated in a series of clinical studies and shown to be well tolerated with good clinical efficacy. Depot pollen-allergoids were introduced into the German market in 1987 under the trade name Allergovit® and are now firmly established and recommended primarily for shortcourse preseasonal immunotherapy in pollinosis. Allergovit® is currently available in many European and non-European countries. A placebo-controlled study design was chosen as improvements in the symptoms of pollen allergies can not be shown over time, as pollen seasons of different years are not comparable. Due to the different mechanisms of action, specific immunotherapy can not be compared with anti-allergic drugs. Thus the only chance to prove efficacy for specific immunotherapy (SIT) is to test versus a parallel placebo group.