Standardized extracts.
Until recently, physicians practicing allergy have not had the benefit of using allergenic extracts with potencies expressed in uniform, meaningful units. Technologic advances have provided accurate and reproducible methods for qualitative and quantitative analyses of these products, and assignment of meaningful units can be accomplished by using a threefold serial dilution titration skin test and appropriate in vitro methods. Although the perfect method for standardization of allergenic extracts has not yet been developed and some confusion has been created in the process, significant improvement in the quality of allergenic extracts has resulted. Collaborative efforts of regulatory agencies, manufacturers, specialty organizations, and clinicians should continue to produce standardized extracts that offer significant advantages to physicians practicing allergy.