Sublingual Immunotherapy and Oral Immunotherapy: Are WE There Yet?

James Thompson, MD Health Pro
  • Many publications about sublingual immunotherapy (SLIT) have been cited in recent years. Sublingual immunotherapy is widely used in Europe as a form of desensitization. Desensitization is a method of making a person less sensitive to allergy triggers (for example pollen, dust mites, cat, dog).

     

     

    Sublingual Immunotherapy is different from Oral Immunotherapy
    Some published reports have interchangeably used the term sublingual immunotherapy and oral immunotherapy (OIT). SLIT is a form of desensitization that involves the placement of a specified amount of allergy extract under the tongue and holding it there for a few minutes before swallowing it. In contrast, people that get OIT are instructed to immediately swallow the allergy extract.

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    The mechanisms of allergic tolerance are different for SLIT compared to OIT. The majority of reports from Europe, where both forms are commonly used, refer to the emerging benefits of SLIT, not OIT. In fact, many allergy experts in Europe do not feel OIT is very effective.


    Comparing SLIT and "Allergy Shots"
    The following comments address comparisons between SLIT and subcutaneous immunotherapy (SCIT), more commonly known as allergy shots. Allergy shots are the most common means of desensitization used in the United States, most effectively by trained allergy specialists. Recent publications have addressed the effectiveness and safety of SLIT compared to SCIT (under the tongue vs. allergy shot).

    The American Academy of Allergy, Asthma and Immunology (of which I am a member) has reviewed and continues to follow many published reports on SLIT.

    I recently reviewed published clinical trials on SLIT as well as a few comparison studies on SLIT and SCIT (Journal of Allergy and Immunology 5/2006 p1021). Most of the publications are from Europe. First, allergens in Europe are likely different, to some extent, from allergens in the United States. Second, most of the studies involved small numbers of patients. The small numbers of patients in many of the SLIT trials weaken their results.
    In contrast, many studies in the U.S. on patients getting allergy shots involve large numbers of patients.

    The results? Less than 40% of the trials on SLIT showed benefit in controlling allergy symptoms and reducing the need for allergy medication. Data on allergy shots studied in the U.S. report more than 50% of the trials to be effective in both areas.

    The good news about SLIT is:

    1) It does not require a shot (NO NEEDLES!!!)

    2) It is a safer means of providing immunotherapy compared to the allergy shots (there's a much lower risk of anaphylaxis)

    3) It offers a chance to reduce allergic sensitivity with a home therapy program (fewer office visits).

    4) It may allow younger children (under age 5) to be started on immunotherapy, as opposed to allergy shots, where we generally wait until school age before considering them.

    5) As seen in many reports on SCIT, some studies have shown long term benefit (reduced allergy or asthma symptoms years after stopping treatment).



  • The bad news about SLIT is:

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    1) In many of the SLIT studies, single allergens are used (for example, just grass or dust mite). Many allergy sufferers in the U.S. have multiple allergy triggers. SCIT (allergy shot) targets several allergens at the same time.

    2) There are no established guidelines for potency, quantity or quality of extracts used for SLIT. The published clinical studies vary widely in how much oral extract is used.

    3) There are also no guidelines on how often or how long one should get SLIT.

    4) The FDA (Food and Drug Administration) has not yet approved SLIT for use in the U.S.

    5) There are few well controlled studies comparing SLIT to SCIT. SCIT edged out SLIT in most of the studies which compared their effectiveness.

    Many publications about sublingual immunotherapy (SLIT) have been cited in recent years. Sublingual immunotherapy is widely used in Europe as a form of desensitization. Desensitization is a method of making a person less sensitive to allergy triggers (for example pollen, dust mites, cat, dog).


    What will the future bring for immunotherapy?
    SLIT will likely be approved by the FDA for single allergen therapy. More extensive research will lead to the development of guidelines for dosing and other important management issues. SLIT will not likely replace SCIT any time soon. On the other hand , SLIT may offer an alternative to patients that are young, fearful of needles, have a single allergen trigger or have other issues that make SCIT less desirable.

     

    Are We There Yet?  

    The Answers:

    No for Oral Immunotherapy (OIT), we are not even close.
    No for SLIT also, but we appear to be close.

    Do you have any other thoughts on Sublingual immunotherapy?

    What is your experience with desensitization?
     

Published On: March 30, 2008