Standardization of allergenic extracts: a manufacturer's perspective.

The current procedure for standardizing allergenic extracts utilizes quantitative skin testing techniques and in vitro techniques. A reference preparation is selected and tested using a sensitive intradermal skin test technique to determine allergy units. Subsequent batches of standardized extracts are compared to the reference preparation using in vitro techniques. The standardization program has accelerated over the past few years and all indications are that it will continue to do so in the future.