A controlled dose-response study of immunotherapy with standardized, partially purified extract of house dust mite: clinical efficacy and side effects.

BACKGROUND: Seventy-four asthmatic patients allergic to house dust mite were included in a double-blind, controlled study to establish the optimal maintenance dose of a standardized extract of Dermatophagoides pteronyssinus (Der p I) during 24 months of immunotherapy (IT).

METHODS: The patients were given the following maintenance doses: 19 patients 10,000 standardized quality units (SQ-U) (group 10, 0.7 microgram Der p I), 20 patients 100,000 SQ-U (group 100, 7 micrograms Der p I), 16 patients 300,000 SQ-U (group 300, 21 micrograms Der p I), and 19 control patients (group 0) had no injections. After 24 months bronchial challenge demonstrated a dose-related increased tolerance to Der p I, group 10 (p = 0.003), group 100 (p = 0.0005), group 300 (p = 0.0007), with no change in group 0 (p = 0.6). Patients given IT had a decrease in medication and peak expiratory flow score. In total, 2104 injections were given, and 3.5% were followed by a systemic reaction, defined as a fall 15% or greater in forced expiratory volume in 1 second within 30 minutes. A dose-response relation was demonstrated, with rates of systemic reactions in percent of injections; group 10, 0.56%; group 100, 3.30%; and group 300, 7.10% (p < 0.0001). No anaphylactic reactions occurred, and no late systemic reactions were observed. This study demonstrated a dose dependence of efficacy and side effects of IT in asthmatic patients. We suggest a maintenance dose of 100,000 SQ-U (7 micrograms Der p I) as an appropriate guideline for IT with house dust mite extract.