CAT EXTRACT LABELING CHANGES SHOULD REFLECT IDENTITY OF ALLERGEN, ADVISORY CMTE. CONCLUDES; FDA WILL RULE ON CATEGORY IIIB ALLERGENIC EXTRACTS IN EARLY 1992

Cat allergenic extracts labeling should be changed so that physicians administering the extracts will be aware of whether the products contain fel d1 or other cat allergenics, FDA's Allergenic Products Advisory Committee concluded at its Dec. 13 meeting. The committee reviewed data presented by Paul Turkeltaub, MD, of FDA's Laboratory of Allergy and Immunochemistry, showing that all of the currently marketed cat extracts contain either the fel d1 allergen or "some other non-fel d1 component" identified by Turkeltaub as serum albumin. Noting that "a minority of people [approximately 20%] react only to the serum albumin," which is contained in cat pelt extracts, Turkeltaub said that "labeling should reflect the identity [of an extract's allergen] as best we can tell." He suggested that "we can have two categories -- standardized cat pelt extract and standardized cat extract." Committee member John Ohman, MD, New England Medical Center, also urged a labeling change for cat extracts. "There is concern that switching from an epithelial extract that contains no albumin inadvertently to a deeply potent material of pelt may be hazardous to some people," Ohman commented. The committee also recommended that standard labeling designations for the potency of cat extracts be converted from 100,000 allergy units to 10,000. As part of FDA's effort to standardize potency ratings of all allergen extracts, the agency's Turkeltaub explained that the "arbitrary" rating of standardized cat extract potency as 100,000 allergy units should be changed to 10,000 units to reflect the extract's actual potency relative to that of other extracts. He added that "the clinical data supports the designation of 10,000 allergy units." Committee member Dianne Schuller, MD, Geisinger Medical Center, (Danville, Penn.), said, "I think [changing the potency labeling from 100,000 to 10,000 allergy units is] dangerous because I'm convinced [physicians] will assume it's the same strength and use 10 times the amount." The same concern was first voiced when the committee discussed the labeling change at its Feb. 6 meeting ("The Pink Sheet" Feb. 11, p. 16). Turkeltaub said that the safety issue could be addressed with "a physician education program, supplemental labeling with a warning box," and a "FDA drug bulletin." Several committee members suggested that a new name for the converted units should be found to avoid confusion with the original units. John Salvaggio, MD, Tulane University, said: "I think it is very unwise to use the same name" for the converted units. The new unit name would be applied to all standardized allergen extracts to show their relative potencies. Committee member Charles Reed, MD, Mayo Clinic, supported a standardized potency unit for all extracts, saying that "allergy treatment should be biologically equivalent across allergies." Turkeltaub said this would involve "a massive labeling change" to all marketed allergen extracts. Pending the resolution of the labeling issues, FDA "is going to have to push back" the deadline for allowing nonstandardized cat extract to remain on the market by "six to 12 months," Chris Anderson of the Laboratory of Allergy and Immunochemistry said. In a 1989 letter to extract manufacturers, FDA had said that nonstandardized cat extract would not be allowed on the market after Jan. 1, 1992. In the first quarter of 1992, FDA plans to revoke marketing authority for over 400 Category IIIB allergenic extracts unless further data showing efficacy has been submitted to the agency by then, the committee was told by FDA Division of Regulations and Bioresearch Monitoring Director Steven Falter, MD. A IIIB classification means that an extract is not marketable, pending further supporting data. The notice of opportunity for comments for category IIIB allergen extracts was published in August 1985. Falter added that "we will then turn our attention to the category IIIA extracts," which number "over 1,200 for immunology alone" plus "about 1,000 for diagnostic use." Category IIIA extracts were allowed to remain on the market, pending further studies to demonstrate efficacy. Falter said these will be reviewed and recategorized as either Category I or Category II and that a proposed rule on the reclassification should be ready in the first quarter of 1993. "I would expect that a number of hearings would be requested," to review category IIIA extracts, Falter cautioned, but he predicted a final rule on the extracts in 1995.