Background: Widely accepted loading protocols for rush subcutaneous immunotherapy (rSCIT) have not been established. Our aim was to evaluate the loading protocols of rSCIT.
Methods: In the low initial dose group (33 patients), the initial dose of standardized house dust mite extract was 1 JAU or less. The target dose at the end of the rush build-up phase was 500 JAU. Next, the initial dose was increased to 10 JAU with the same target dose in the high initial dose group (18 patients). Furthermore, in the modified high initial dosage group (17 patients), the initial dose was 10 JAU but the target dose at the end of the rush phase was 300 JAU. Then, the maintenance dose of 500 JAU was administered at 9 or 10 days after rSCIT initiation. We retrospectively evaluated these protocols.
Results: A systemic reaction (SR) occurred in 28 out of 33 (84.8%) patients in the low initial dosage group and in 12 out of 18 (66.7%) patients in the high initial dosage group, on the other hand significantly reduced in 4 out of 17 (23.5%) patients in the modified high-dosage group. The amount of antigen reached 339.3±19.0 JAU in the low initial dosage group and 358.3±24.9 JAU in the high initial dosage group at the end of the rush phase, significantly increased 452.9±20.6 JAU in the modified high-dosage group at 9 or 10 days.
Conclusion: In rSCIT using standardized house dust mite extract, lowering the target dose at the end of the rush phase and delaying the administration of the maintenance dose may reduce SR and increase the reached amount of antigen.
Keywords: rush subcutaneous immunotherapy; standardized house dust mite extracts.