Sublingual or Oral Immunotherapy
Sublingual or Oral Immunotherapy is a form on immunotherapy which is administered by administering allergens under the tongue (sublingual) or swallowing (oral). The idea has been around for more than 50 years. It has been used for few decades in Europe, and more recently in the United States. FDA approved 3 formulations for use in 2014 – two (Grastek, Oralair) for grass pollen allergy and one (Ragwitek) for ragweed pollen.
Sublingual or Oral Immunotherapy Availability
- Sublingual allergen tablets (SLIT tablets): These are the only FDA approved sublingual allergen immunotherapy in USA.
- Sublingual liquid allergen extract (SPLIT drops): These are used frequently in Europe. Some physicians in US use it. These are not FDA approved. Optimum dose and frequency of administration has not been worked out, insurance companies don’t cover it but patients like it for convenience factor.
- Other formulations like enteric coated tablets have been investigated.
How Does Sublingual or Oral Immunotherapy Work?
SLIT hasn’t been studied as well as SCIT, but probably induces changes similar to that induced by allergy shots.
Who Should Get Grastek, Oralair and Ragwitek?
Patient needs evaluation by an allergist to ascertain that patient’s symptoms are due to grass or ragweed allergy. Skin or blood test must be done to confirm allergy to grass, ragweed or aeroallerhens.
Positive skin or blood test are not suffice to use the Grastek, Oralair or Ragwitek. One must decide the causal relationship between pollen and patient symptoms. For example, patient who has symptoms in April and early May and start to subside towards late May and are very mild in June is unlikely to benefit from Grass tablets even if they have positive skin test for grass pollen. This patient has tree allergy for whick we don’t have sublingual treatment.
When and How Long Should It Be Given?
Patient starts the treatment 12 weeks before the pollen allergy season and continues through the pollen season. In Iowa, the grass pollen season starts in early May and continue through the end of July. Grastek or Oralair is started in January and continued through the end of July. Come the next year, one need to start this cycle again. Some patients have taken Grastek throughout the year for as long as 3 years and have shown to have some residual effect in year 4 even when they didn’t take Grostek.
In Iowa, ragweed season starts mid August and dies down with first frost. Start Ragwitek in late April and continue until first frost.
Do I Need to Take It in Doctor’s Office?
First dose of any one of these is given in the physician’s office. Rest of the doses are given at home.
How Effective are Sublingual Pollen Tablets?
On average, as compared to those who used sugar pills (placebo), patients who used Grastek, Oralair or Ragwitek experienced 25-35% less symptoms and used less medications.
Side Effects of Sublingual Allergy Tablets
- Most common side effect of sublingual allergy tablets are itchy mouth, throat irritation, itchy ears, sensation or acute swelling of mouth.
- It is rare to have anaphylaxis following sublingual allergy tablets, but have occured. these usually occur with the first tablet, but may happen with subsequent doses which are given at home.
- Rarely patients have developed difficulty swallowing due to inflammation of food pipe, called eosinophilic esophagitis.
When Should Sublingual Allergy Tablets be not Used?
- Uncontrolled asthma. OK to use in patient with mild intermittent or persistent but controlled asthma
- Oral ulcertation or oral inflammation
- Safety in pregnancy is not established
- Safety when given along with subcutaneous immunotherapy is not established
- Patients receiving beta-blockers
Advantages and Disadvantages of Sublingual Allergy Tablets
- SLIT appears safer than SCIT, but serious reaction do occur occasionally
- SLIT is more comfortable, more convenient than SCIT
- Patients who regularly miss doses may not achieve good results
- There are few trials which have compared sublingual approach to allergy shot approach, and allergy shot approach was felt more effective
- Major limitation of sublingual approach is that it is currently available in U.S. for single allergens like grass and ragweed. Large number of patients are poly sensitized (allergic to trees, cat, dogs, other animals, dust mites, molds and cockroach etc.). Patients with multiple allergies get treatment for all allergens at the same time if one uses allergy shots. This is not feasible with Grastek, Ragwitek or Oralair