Immunotherapy involves regular injections of an offending allergen over a period of months, with the goal of reducing symptoms. It begins with low doses to prevent unfavorable reactions, with gradually increasing doses injected once or twice a week as immunity to the antigen develops. After the maintenance dose is achieved, the interval between injections may range between two and six weeks. Immunotherapy may be administered continuously for several years.
Sublingual immunotherapy (SLIT) is a potential alternative to subcutaneous immunotherapy for providing allergen-specific therapy. It is proposed as a more convenient alternative delivery route for treating a variety of allergic disorders.
Allergen-specific immunotherapy involves administering well-characterized allergen extracts, the potencies of which are measured and compared with a reference standard. An initial induction or build-up phase progressively increases the allergen dose; this is followed by multiple years of maintenance injections at the highest dose. Allergen-specific immunotherapy has been used to treat a variety of conditions including insect allergy, allergic rhinitis, and asthma. Subcutaneous injection of allergen-specific immunotherapy is the standard approach. Due to the inconvenience of multiple injections, particularly in children, alternative delivery routes have been investigated; of these, sublingual immunotherapy (SLIT) is the most prominent. SLIT targets absorption to the sublingual and buccal mucosa. Allergen preparations used for SLIT are held under the tongue for one to several minutes and then swallowed or spit out.
