Clinical efficacy and tolerability of a steady dosage schedule of local nasal immunotherapy. Results of preseasonal treatment in grass pollen rhinitis.

Background: Local nasal immunotherapy (LNIT) is an effective and safe alternative to conventional subcutaneous immunotherapy. A specific nasal provocation test (SNPT) could be used to indicate the optimal subclinical dose to carry out LNIT.
Objective: We hypothesize that LNIT could be carried out with only one predefined dose for all patients, so we have evaluated the efficacy and the tolerability of LNIT administered at steady dosages in patients with seasonal allergic rhinitis.
Methods: Twenty grass pollen-sensitized patients suffering from seasonal allergic rhinitis were studied in a randomized, double-blind, placebo-controlled trial. The treatment was carried out according to a schedule based on the administration of a steady subclinical dosage of the allergenic extract, selected on the basis of the sensitivity threshold of the SNPT. The patients were divided into two groups of 10 people each, which were treated either with grass pollen extract in a hydroglyceric solution or with placebo.
Results: During the peak pollen period, with regard to the placebo (P) group, in the grass treated (GT) group a significant decrease of both nasal symptoms (P = .021) and consumption of antihistamines (P = 0.047) was found. Furthermore, only in the GT group was the provocative dose assessed by the SNPT significantly lower (P = .049) at the end of the treatment. In this group of patients an inverse correlation between such provocative dose and the nasal symptom score reported during the peak pollen period was also evidenced (r = 0.708; P = .038). Adverse reactions to LNIT were mild, rare, and did not interfere with the completion of the therapeutic schedule.
Conclusions: Our study indicates that LNIT, when administered at steady dosages, may be proposed as a treatment for grass pollen seasonal allergic rhinitis as it appears to be effective and well tolerated.