Tolerance of a cluster schedule with a house dust mite extract quantified in mass units: multicentre study © 2004 Esmon Publicidad J Invest Allergol Clin Immunol 2004; Vol. 14(3): 193-197 Original Article Tolerance of a cluster schedule with a house dust mite extract quantified in mass units: multicentre study A. I. Tabar 1 , L. Fernández-Távora 2 , R. Alonso 3 , R. Castillo 4 , A. Cisteró- Bahima 3 , F. de la Torre-Morín 5 , J. Fernández 6 , B. E. García-Figueroa 1 , S. Fernández 7 , J. J. García-González 7 , J. C. García-Robaina 5 , F. Moreno 8 , P. Lobatón 8 , I. Sánchez-Machín 5 , F. de la Torre-Martínez 9 . 1 Hospital Virgen del Camino, Pamplona, Spain - 2 Ambulatorio Virgen de la Cinta, Huelva, Spain - 3 Instituto Universitario Dexeus, UAB, Barcelona, Spain - 4 Hospital Dr. Negrín, Las Palmas de Gran Canaria, Spain - 5 Hospital Universitario Ntra Sra de la Candelaria, Tenerife, Spain - 6 Hospital general Universitario de Elche, Alicante, Spain - 7 Hospital regional Universitario Carlos Haya, Málaga, Spain - 8 Clínica Dr. Lobatón, Cádiz, Spain - 9 ALK-ABELLÓ, S.A., Madrid, Spain Introduction Subcutaneous immunotherapy is normally administered during a build-up phase, using treatment regimes that start with low concentrations of the allergen with one dose per week, and reaching the maintenance dose after a period that usually varies between 12 and 15 weeks. This form of treatment, endorsed by a large number of clinical trials testing safety and efficacy, has as its fundamental objective to induce in the patient a progressive tolerance to the allergen responsible for setting off the allergic process during the initiation phase, considered as the phase with the greatest risk of adverse reactions. The purpose of this is to reach the maintenance or therapeutically effective dose, capable of interfering with the immunopathological mechanisms of the allergic disease, with the least possible adverse effects. However, in the 80’s, especially in patients with an allergy to Hymenoptera venom, new more aggressive treatment methods were developed in which the optimal treatment dose was reached within a period as short as hours, thus avoiding the life-threatening risk implied Summary. The standardisation of allergenic extracts in micrograms of the major allergen has encouraged the search for new treatment schedules, with the purpose of shortening the number of visits and doses required to reach the maintenance dose without eliciting a greater risk of adverse reactions for the patients. With this objective, a prospective multicentre pharmacovigilance study was designed that included 200 patients with allergic rhinoconjunctivitis and/ or allergic asthma sensitised to mites (Dermatophagoides pteronyssinus and/or farinae). The dose increment period was carried out using a cluster schedule, where the optimal dose was reached after 4 visits, administering two doses in each visit. The duration of the study was 5 months and a total of 1902 doses were administered. At the end of the trial, 31 adverse reactions in 23 patients were recorded. Six of these were systemic (0.3% of the administered doses) recorded in 6 patients (3% of the sample). One was an immediate reaction (grade 1) and 5 delayed (4 mild and 1 moderate). Two were asthmatic exacerbations, 2 cutaneous reactions, 1 rhinitis and 1 an unspecific symptom (not IgE-mediated). Two appeared upon administration of the first vial and the remaining 4 after administration of the third cluster. Therefore, the schedule tested presents an adequate tolerance profile, suggesting savings (compared to the conventional schedule of 13 doses per patient) of 1800 visits and 1000 treatment doses in the whole study. Keywords: Rhinoconjunctivitis, Asthma, Cluster Immunotherapy, Pharmacosurveillance, Mites.