(HealthDay News) — For adults with birch pollen-induced allergic rhinitis, a sublingual birch pollen preparation (SB) is associated with improvement in symptom scores vs. placebo, according to a study published online September 3 in Allergy.

Oliver Pfaar, MD, from the Center for Rhinology and Allergology Wiesbaden in Germany, and colleagues conducted a combined tolerability and dose-finding study with SB involving 269 adults with birch pollen-induced allergic rhinitis. Participants were randomly allocated to placebo or to SB at concentrations of 3,333, 10,000, 20,000, or 40,000 AUN/mL. At baseline and after five months of treatment, the authors determined the differences in symptom scores following a titrated nasal provocation test.

The researchers found that symptom scores improved in all treatment groups after treatment vs. baseline, with an additional stepwise improvement in the active groups vs. placebo that was significant in high-dose groups (P=0.008 and P<0.001, respectively). A significant linear dose-response curve was observed for this primary end point: The higher the dose, the better the improvement. Compared with placebo, active treatment correlated with increased peak nasal inspiratory flow and serum immunoglobulin G levels. Improvements were highest in the 40,000 AUN/mL group. More adverse reactions were seen for all active doses vs. placebo, which were primarily mild and well controlled.

“All active treatment groups showed better responses than placebo for both primary and secondary parameters,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry; Pharm-Olam International provided assistance in conducting the study. HAL Allergy B.V., sponsored the trial.

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