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Background: Allergen immunotherapy (AIT) has been in practice for more than 100 years. However, research in novel routes and delivery methods of immunotherapy to treat allergic rhinitis (AR) and conjunctivitis has only recently occurred in the United States, where the predominant form of AIT provided is largely via a subcutaneous immunotherapy (SCIT) route. AIT may prevent new sensitizations, improve symptoms, decrease medication usage, and prevent allergic asthma. Although AIT is the only potentially curative treatment for AR, access and adherence continue to be problematic. Only a fraction of eligible patients actually undergo treatment, and attrition rates are high. An obvious limitation of SCIT includes the requirement of regular injections to be provided in the physician's office due to the potential for anaphylaxis. Sublingual immunotherapy (SLIT) for home administration has been investigated as a potential alternative to address this limitation of SCIT. Methods: A literature review was performed including the current findings from randomized clinical trials and meta-analyses with a discussion of the most recent evidence for the efficacy, safety, and dosing of allergen SLIT. Results: The current data suggest that SLIT is effective for treatment of seasonal allergies, can potentially prevent asthma, and has a favorable safety profile. Head-to-head studies, however, are few, and comparative effectiveness still remains to be answered. Optimal treatment algorithms for SLIT have not yet been established, with wide variation in dosage selection and schedules. Similarly to SCIT, only a few allergens such as ragweed and grass pollen have been found to be effective in large clinical trials. Conclusion: Recent data indicate that SLIT is an effective treatment modality for seasonal AR, improve quality of life, and can potentially prevent asthma but head-to head studies comparing SLIT to SCIT are needed. [ABSTRACT FROM AUTHOR]

Background: Increasing interest in sublingual immunotherapy (SLIT) among practitioners and patients has resulted in numerous publications and clinical trials in recent years. With the clinical growth of SLIT, discussions of its efficacy, safety, and immunologic effects have intensified, as have comparisons to subcutaneous immunotherapy (SCIT). In the United States, SCIT has been the traditional form of immunotherapy for inhalant allergy and is the only immunotherapy method approved by the U.S. Food and Drug Administration at this time. The similarities and differences between SLIT and SCIT are often discussed, yet clinical studies directly comparing these immunotherapy methods are scarce. Methods: A literature review of specific issues and controversies between SLIT and SCIT for allergic rhinitis was conducted. Results: Safety, efficacy, and immunologic effects of these two immunotherapy techniques are reviewed. Conclusion: Unanswered questions relating to SLIT are examined. [ABSTRACT FROM AUTHOR]

Background: Few trials of sublingual immunotherapy (SLIT) in the United States have been reported. Objective: This randomized, placebo-controlled feasibility SLIT study compared the safety and physiologic effects of high- versus low-dose Dermatophagoides farinae vaccine. Methods: Thirty-one D farinae–sensitive adults with allergic rhinitis with or without mild intermittent asthma were eligible for randomization to high-dose maintenance vaccine (n = 10, 4200 allergen units [approximately 70 μg of Der f 1/d]), low-dose maintenance vaccine (n = 10; 60 allergen units [approximately 1 μg of Der f 1/d]), or placebo (n = 11) over 12 to 18 months. Medication-symptom scores and adverse events were monitored, serum D farinae–specific IgE and IgG4 levels were measured, and bronchial reactivity to D farinae was determined at baseline and 6-month intervals. Results: Of the 31 randomized subjects, 6 withdrew because of non–treatment-ascribed events. Four withdrew because of treatment-ascribed effects: high-dose group, 1 of 10 (gastrointestinal symptoms); low-dose group, 1 of 10 (gastrointestinal symptoms); and placebo group, 2 of 11 (headache and increased nasal symptoms). Thus 21 subjects completed the study: high-dose group, 9; low-dose group, 7; and placebo group, 5. Eleven of the 21 subjects experienced mild-to-moderate gastrointestinal symptoms, throat irritation, or both (high-dose group, 5/9; low-dose group, 4/7; and placebo group, 2/5). No severe systemic reactions were noted. No differences in symptom-medication scores were found. High-dose SLIT increased the bronchial threshold to allergen challenge and increased serum D farinae–specific IgG4 levels, whereas low-dose SLIT and placebo had no significant effect. Conclusions: High-dose D farinae SLIT was generally tolerable, increased serum D farinae–specific IgG4 levels, and improved the bronchial threshold to allergen challenge. Larger US trials are warranted. [ABSTRACT FROM AUTHOR]