EFFICACY AND SAFETY OF ORAL IMMUNOTHERAPY WITH SHORT RAGWEED EXTRACT

Background: Oral immunotherapy, if proven safe and effective, could be an alternative to subcutaneous immunotherapy. Objective: This pilot s tudy investigated the clinic and immunologic effects of ragweed immuno therapy using a new microencapsulated, pH-sensitive, oral delivery sys tem. Methods: A double-blind, placebo-controlled trial was conducted i n 23 patients with allergic rhinitis to short ragweed. Following a bas eline nasal challenge with ragweed allergen, oral immunotherapy with e ncapsulated short ragweed extract or placebo was administered once dai ly, 6 days/week. Doses began at 3 mu g Amb a 1 per day and were increa sed by 3 mu g every three days as tolerated, to a maximum daily mainte nance dose of 24 mu g. A nasal challenge was repeated 6 weeks later, f ollowed by the continuation of maintenance therapy through the natural ragweed season. Daily allergy symptoms and relief medication usage wa s recorded. A final nasal challenge was performed at the end of the na tural season. Short ragweed-specific serum IgE, IgG, and IgG(4) antibo dy levels were measured every 2 weeks during the study. Results: Maxim um tolerated doses ranged from 6 to 24 mu g Amb a 1 per day (74% reach ed 24 mu g). Adverse events were not serious or different between the active and placebo groups. The active treatment group showed increases in short ragweed specific serum IgG and IgG(4) antibody levels. Sympt om scores during the natural season were numerically but not statistic ally lower in the active treatment group. This group also experienced a greater reduction from baseline in nasal reactivity as assessed by n asal challenge. Conclusions: These pilot data suggest that the encapsu lated, pH-sensitive oral immunotherapy delivery system was safe, induc ed a brisk serologic response, and attenuated the symptomatic response to both experimental and environmental ragweed exposure.