Local immunotherapy by inhalation of a powder extract in asthma due to house dust mite Dermatophagoides pteronyssinus: a double-blind comparison with parenteral immunotherapy.

To verify the efficacy and the tolerability of local immunotherapy (LI) by inhalation of a powder extract of house dust mite (HDM), in comparison with parenteral immunotherapy (PI) by injection, 10 patients with asthma due to HDM were studied in a blind fashion. 5 patients (Group A) underwent LI and subcutaneous injections of placebo, 5 patients (Group B) underwent PI and inhalation of lactose for 6 months. In both groups each inhalation was preceded by premedication with disodium cromoglycate (DSCG) (40 mg). In Group A a significant decrease in symptoms score and in peak expiratory flow (PEF)-derived parameters was observed already after 3 months of treatment, and 2 patients lost the late component of the bronchial response to the challenge with HDM. No significant variation was found in bronchial responsiveness to methacholine and ultrasonically nebulized distilled water (UNDW) and in immunologic humoral and cellular parameters in peripheral blood after treatment in either group. No local important adverse reactions were observed in Group A and no systemic side effects were observed in either group. We conclude that LI is as effective as PI, but more rapid in its action, in the treatment of asthma due to HDM. Moreover, LI is locally well tolerated, providing DSCG is inhaled before each therapeutic inhalation, and does not induce systemic side effects.