Under the Tongue vs. Under the Skin

By Dr. Paul Ehrlich

The article in the New York Times started off looking like another inflated assessment of a somewhat novel allergy treatment.  A woman from Joe Namath’s hometown, Beaver Falls, Pa. was quoted on the simplicity of taking drops under her tongue at home compared to the inconvenience and expense of going to the allergist for shots.  This was in the business section, so it was accompanied by news that Merck and a French company want permission to sell tablets for grass pollen allergies.  In support of their quest for fast-track approval by the FDA, the companies are citing acceptance of this approach in Europe.*

Unlike most other articles in the mainstream press (okay, lots of people would argue that the Times isn’t mainstream) this one goes on to describe the other side of the issue in terms that we could have argued in these pages, and indeed, in many cases already have.

I have never used sub-lingual immunotherapy, which goes by the charming acronym SLIT. The prospect of waiting for development and certification a series of tablets to a variety of allergens gives me a headache on behalf of my patients, but according to the Times, 11% of allergists aren’t waiting.  They are relying on a crude adaptation of sera packaged for injection, sub-cutaneous immunotherapy aka SCIT.  I prefer giving shots primarily because I know they work, especially for multiple allergens.

As for the theoretical preference for oral dosing instead of shots, the article cites the same study Larry wrote about recently, which shows that Dutch patients are even less compliant with SLIT than with SCIT.  Part of the reason is that oral dosing can produce some nasty sensations.  The Times writes, “The sublingual treatments can cause throat irritation as well as itching and swelling in the mouth, but almost never anaphylaxis.”  I can only imagine that the sensation is a lot like oral allergy syndrome, OAS, which is a form of food allergy that occurs when you are allergic just to food components that are also potent environmental allergens, not the ones associated with anaphylaxis.  The peanut component, Ara h8, for example, is also responsible for allergic reactions to birch pollen.  Many OAS patients react to allergens in fresh fruit, although cooking breaks down those proteins so they are no longer allergenic.

If many patients find the sensation unpleasant enough to discontinue their therapy as many clearly do according to the Dutch study, I can only imagine what will happen if Merck and other companies ever succeed in combining multiple allergens into a single squirt or tablet.  “Let’s see, is my mouth on fire today because of the dust mite or the cockroach?”  Add to that the pain-in-the-neck factor of daily dosing and the drip, drip, drip of co-payments already familiar to asthmatics and you’ve got a real compliance problem.

Does this mean SLIT is a lost cause?  Not entirely.  Based on some new research I have heard about, I think it has potential as an adjunctive therapy for certain allergies in highly motivated, severely allergic patients.  But as a replacement for shots, I don’t think its time has come.

*Reuters now reports: “A panel of experts advising the U.S. Food and Drug Administration said an oral drug made by Merck & Co was effective in treating grass pollen allergy but expressed concerns about the drug’s safety in children.” {The FDA is not bound by this recommendation.}