November 6 (HealthDay News) -- Even though orally delivered "sublingual immunotherapy" (SLIT) is used to treat allergies in a number of countries, there are unanswered questions about its effectiveness, appropriate use, dosage and safety of administration, according to experts at the annual meeting of the American College of Allergy, Asthma & Immunology (ACAAI), in Seattle.

SLIT -- a therapy considered investigational in the United States -- involves absorption of allergens into the body through the membranes of the mouth. Like traditional allergy injections, this is designed to help the body fight specific allergens.

"The main advantage of SLIT over traditional immunotherapy is patient convenience, since it is not an injection but oral drops or tablets that can be administered at home, and it appears to be safer than conventional immunotherapy," Dr. Ira Finegold, clinical professor of medicine at Columbia University and chairman of the R.A. Cook Institute of Allergy, St. Luke's-Roosevelt Hospital in New York, said in an ACAAI news release.

"Sublingual immunotherapy has gained wide acceptance in the treatment of allergic disease throughout Europe and South America, but the research studies in the United States have yet to show results that will convince the FDA to approve a product," Finegold said.

"We do not know the optimal dose for U.S. licensed allergen extracts for SLIT," added Dr. Linda Cox, assistant clinical professor of medicine at Nova Southeastern University College of Osteopathic Medicine in Fort Lauderdale, Fla. "There is no consistent relationship between allergen dose and clinical efficacy. Each formulation including U.S. licensed extracts will need to demonstrate its effective dosing regimen."

She noted that since "SLIT treatment is administered at home with no direct medical supervision, the physician will need to provide specific instructions to patients on how to manage adverse reactions, unplanned treatment interruptions, situations in which the dose should be withheld, and dosing adjustments for any or all of these variables."

SOURCE: American College of Allergy, Asthma & Immunology, news release, Nov. 6, 2008