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Sublingual Immunotherapy (SLIT)Treatment for Allergic Rhinitis Nothing to Sneeze About Allergic rhinitis, sometimes referred to as hay fever, is an inflammatory disease that causes sneezing, itchy/watery eyes, itchy/runny nose and congestion. For millions of sufferers, antihistamines and nasal corticosteroid medications provide temporary relief of symptoms. For others, allergy shots (subcutaneous immunotherapy or SCIT) are a long-term treatment alternative. Allergy shots involve frequent injections of increasing amounts of allergen extract. They can be effective at controlling symptoms of allergic rhinitis, but the injection schedule can be difficult to maintain, local reactions to the injections are common, and severe allergic reactions and even deaths have been reported. Another form of therapy is currently being investigated in clinical research settings for use in the United States. Sublingual Immunotherapy (SLIT) involves a dosing schedule of increasing amounts of allergen, much like the shots. However, rather than shots, the allergens are administered in a liquid form under the tongue. SLIT is currently being used in Europe and some countries in South America. Based on reviews of research projects done both here in the US and overseas, SLIT has the potential to be a safe and effective treatment for allergic rhinitis. SLIT appears to have a favorable safety profile. In one review of the literature, the authors estimated that in approximately 1.2 million doses administered to 4400 patients, there were no serious, "life-threatening reactions". There are reports of anaphylaxis with SLIT, but the incidence is rare. The primary symptoms reported by subjects receiving SLIT included mild "local" itching/burning of the mouth or lips, increase in rhinitis symptoms, gastrointestinal symptoms, and rarely, an increase in asthma symptoms. The reactions reported by subjects receiving SLIT were only significant enough to make the subject stop taking SLIT in less than 5% of the cases. SLIT has been studied in children as young as a year old. The primary symptoms reported by parents were oral itching, itchy skin, abdominal pain, and nausea and vomiting. The effectiveness of SLIT has been studied in both adults and children. Some studies report that SLIT takes at least 2 years of treatment before subjects see improvement in symptoms. Other studies show improvement within a single year of therapy. One large review of over 100 SLIT research studies demonstrated that about 1/3 of studies showed significant improvement in symptoms while 1/3 showed no significant improvement. The variation in effectiveness had been attributed to the differences in the dose of allergen used for the various studies. In general, the higher doses of allergen appeared to have the largest impact on symptom improvement. SLIT has potential to become a useful treatment of allergic rhinitis. Several questions need to be answered before SLIT can be used outside of the research domain. The optimal starting dose and dosing frequency for maintenance have not been established. It's not clear if the starting/maintenance doses will be the same for all of the various allergens. Once the dosing questions have been addressed, the cost-effectiveness of SLIT needs to be established. References Cox L, Sublingual immunotherapy and allergic rhinitis. Curr Allergy Asthma Rep. 2008 Apr;8(2):102-10. Cox L. Sublingual immunotherapy in pediatric allergic rhinitis and asthma: efficacy, safety and practical considerations. Curr Allergy Asthma Rep 2007 Nov;7(6):410-20. Cox LS, Linnemann DL, Nolte H, Weldon D, Finegold I, Nelson HS. Sublingual immunotherapy: A comprehensive review. J Allergy Clin Immunol 2006. May;117(5):1021-1035. Passalacqua G, Durham SR in cooperation with the Global Allergy and Asthma European Network. Allergic Rhinitis and its Impact on Asthma update: Allergen Immunotherapy. J Allergy Clin Immunol 2007 April;119(4):881-891. Smith, H, White P, Annila I, Poole J, Andre C, Frew A. Randomized controlled trail of high-dose sublingual immunotherapy to treat seasonal allergic rhinitis. J Allergy Clin Immunol 2004. 114(4);831-837. Wilson DR, Lima MT, Durham SR. Sublingual immunotherapy for allergic rhinitis: systematic review and met-analysis*. Allergy 2005;60:4-12. |
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