The FDA has licensed 9 manufacturers of allergenic extract products to produce new standardized extracts of 8 different grass pollens. Nonstandardized extracts of these grass pollens will no longer be marketed. The new products will improve safety because standardization defines the level of potency and narrows the range of variability from 1 lot to the next. The benefits to patients include enhanced safety when switching from an old vial to a new one and a more reliable response to immunotherapy, since each lot has an established potency. In addition, because each manufacturer measures potency based on the same FDA reference standard, clinicians will have a greater choice of extracts. The professional labeling for the new products, which are not directly interchangeable with the nonstandardized products, contains important information, including directions on how to perform skin testing with the products in order to make a diagnosis of grass pollen allergy, how to select a safe dose when switching from nonstandardized to standardized extracts, and how to initiate immunotherapy. The products should be used by physicians experienced in administering them, as well as in the emergency treatment of anaphylactic reactions. The labeling advises caution in treating asthmatic patients with the products. Serious adverse reactions that may be associated with the use of allergenic extracts should be reported to the FDA MEDWATCH program by calling (800) FDA-1088.
Nightingale SL. New Prescribing Information About Standardized Grass Pollen Extracts. JAMA. 1998;280(5):410. doi:10.1001/jama.280.5.410-JFD80007-4-1