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Executive Summary

BENZOYL PEROXIDE TUMORIGENICITY RISK DATA WILL BE ACCEPTED BY FDA until Aug. 7, 1992 under a proposed rule in the Aug. 7 Federal Register. The notice amends the tentative final monograph for OTC topical acne drugs by reclassifying benzoyl peroxide from a Category I ingredient (generally recognized as safe and effective) to a Category III ingredient (insufficient data available to classify as safe and effective). "Although extensive animal data and human epidemiology data are available, the agency is unable to state that benzoyl peroxide is generally recognized as safe at this time," the proposed rule states. "The agency has determined that further study is necessary to adequately assess the tumorigenic potential of benzoyl peroxide." FDA said it "believes that studies of 18 to 24 months in two species of animals (mouse and rat) are needed to rule out the possibility of carcinogencity." The agency noted that completion and analysis of these studies "may take several years." The acne drug ingredient "has not been subjected to the normally expected long-term (18-24 months) carcinogenicity studies in rodents." FDA believes "the short duration (about 52 weeks) of topical studies, which have shown only 'promotion,' to be insufficient to rule out the possibility of 'initiation.'" From all the submitted data, FDA concluded that "the evidence is substantial to establish benzoyl peroxide as a potent skin tumor promoter in more than one strain of mice and other laboratory animals tested." Benzoyl also increases "the rate of malignant progression of benign epidermal papillomas to squamous cell carcinomas in mice." The agency added that "while the promotional activity of benzoyl peroxide appears to predominate over initiator activity, the agency believes that it is possible that benzoyl peroxide could have a longer latency period as an initiator." The agency determined that "some of the studies contained procedural deficiencies including the following: inadequate numbers of animals, low doses, inadequate data on animal survival, and lack of adequate controls," the proposal says. Some studies did not provide "body weight, age, strain, and sex of the animals," and in other studies "data for both sexes of the animals were pooled." FDA's Antimicrobial II Panel, in its advance notice of proposed rulemaking, and the agency, in its tentative final monograph (January 1985), proposed that benzoyl peroxide be classified as a Category I OTC acne drug ingredient. However, FDA subsequently was made aware of a 1981 study that raised concerns that benzoyl peroxide promoted tumors in mice, and a 1984 study that reported that benzoyl showed tumor initiation potential in mice. FDA Division of OTC Drug Evaluation Director William Gilbertson announced that the agency would be reclassifying the ingredient at a Nonprescription Drug Manufacturers Association conference last November ("The Pink Sheet" Nov. 19, 1990, p. 18). NDMA has submitted safety data on benzoyl peroxide, including animal carcinogenicity studies. However, FDA has maintained that additional long-term animal studies are needed before it can decide on the ingredient's OTC status. In June, at the Drug Information Association's annual meeting, Gilbertson noted that FDA was planning to take the question of benzoyl peroxide's tumorgenicity potential and continued OTC marketing to an advisory committee sometime in the fall ("The Pink Sheet" June 24, T&G-13). He added that the issue could possibly go before the new OTC Drugs Advisory Committee. The proposed rule says that FDA "plans to discuss its concerns and comments received on the agency's conclusions on the data and on continued marketing of benzoyl peroxide with one of its advisory committees at a public meeting to be held in the near future." Gilbertson said in June that the final rule for acne products would follow soon after the rulemaking on benzoyl. FDA said it expects to issue the final rule during the week of Aug. 12. Comments on new data should be filed with FDA by Oct. 7, 1992. Comments or requests for an oral hearing on the proposal should be submitted to FDA by Oct. 7 1991.

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