Background: Specific allergen immunotherapy is most often delivered subcutaneously, but sublingual immunotherapy may confer greater benefit in terms of tolerability and safety, accessibility, and improved antigen delivery.
Objective: This randomized, double-blind, placebo-controlled trial was conducted to identify a safe and effective maintenance dose range of sublingual standardized glycerinated short ragweed pollen extract in adults with ragweed-induced rhinoconjunctivitis.
Methods: In May 2006, a total of 115 patients with ragweed-induced rhinoconjunctivitis were randomly allocated to placebo (n = 40), medium-dose extract (4.8 microg Amb a 1/d; n = 39), or high-dose extract (48 microg Amb a 1/d; n = 36). In a 1-day (rush) dose-escalation regimen, ragweed pollen extract was administered sublingually in incremental doses until maximum tolerable or scheduled dose was reached and then maintained during the ragweed pollen season. Patient diaries were used to monitor nasal and ocular symptoms and medication. The primary endpoint was symptom score.
Results: Both active treatment groups achieved a 15% reduction in total rhinoconjunctivitis symptom scores compared with placebo during the entire ragweed pollen season, but the difference was not statistically significant (P > .10) However, in an analysis of covariance correcting for preseasonal symptoms, both mean daily symptom scores (0.19 +/- 1.16 vs 1.00 +/- 2.30) and medication scores (0.0003 +/- 1.64 vs 0.63 +/- 1.06) for the entire pollen season were significantly reduced in the high-dose versus placebo groups, respectively (P <or= .05). Ragweed-specific IgG, IgG(4), and IgA antibodies were increased after treatment in the medium- and high-dose groups and not the placebo group. Frequency of adverse events was similar between the placebo and treatment groups, but oral-mucosal adverse events occurred more often with treatment.
Conclusion: Standardized glycerinated short ragweed pollen extract administered sublingually at maintenance doses of 4.8 to 48 microg Amb a 1/d was safe and can induce favorable clinical and immunologic changes in ragweed-sensitive subjects. However, additional trials are needed to establish efficacy.