ABSTRACT
Allergen immunotherapy is appropriately performed with vaccines of inhalant allergens or the venom from stinging insects. The term vaccine refers to the solution administered to the patient. The materials used to prepare the vaccine are referred to as extracts. In the United States, allergen extracts are either standardized or nonstandardized extracts in a variety of formulations: lyophilized, adsorbed to aluminum, aqueous or 50% glycerin solutions. Potency is expressed as allergen units (AUs), bioequivalent allergen units (BAUs), content of the major allergen, weight by volume (wt/vol), or protein nitrogen units (PNU).
