PYRETHRIN WITH PIPERONYL BUTOXIDE IS ONLY CATEGORY I OTC PEDICULICIDE UNDER FDA TENTATIVE MONOGRAPH: USP STANDARDS NECESSARY FOR FINAL OKAY
Nonaerosol forms of pyrethrins with piperonyl butoxide are the only OTC pediculicides classified as safe and effective in FDA's tentative final monograph (TFM) for the product class. The TFM is published in the April 3 Federal Register. Although classified Category I in the TFM, FDA notes that because of the possibility of variations in quality and purity of pyrethrins, the ingredient will not be included in the final monograph unless an appropriate composition standard is established. FDA has solicited the United States Pharmacopeial Convention to develop standards for the ingredient. "Should interested parties fail to provide necessary information so that an appropriate standard may be established, pyrethrins will not be included in the final monograph," FDA said. Currently marketed pyrethrin/piperonyl butoxide OTC pediculicides include Norcliff Thayer's A-200 shampoo and gel, Reed & Carnrick's R&C Shampoo, and Leeming's Rid aerosol. The pesticide products are currently under the jurisdiction of the Environmental Protection Agency and, in the absence of an NDA, will remain so until FDA's final monograph is published. Aerosol formulations of pyrethrins with piperonyl butoxide intended for treatment use are classified in Category I for safety and Category III for efficacy. Preventive use, however, is classified in Category III for both safety and efficacy. Based on a review of several safety studies, FDA concluded "that the data are sufficient to establish the safety of aerosolized OTC pediculicide drug products as an alternative suitable dosage form provided that 1) an appropriate applicator is used which facilitates application of the product in close proximity to the affected area and 2) less than 2% of the delivered aerosol (by weight) is comprised of particles smaller than 16 microns in diameter." Aerosolized formulations would also have to be labeled to 1) "state that the mouth and eyes are closed during application and the facial area is appropriately covered (e.g. with a damp cloth during spraying,) 2) . . . state an appropriate time period during which the product can be safely and effectively used before washing off the affected area, and 3) "provide for an initial treatment followed by a second treatment in 7 to 10 days to kill any nits that may have hatched." Discussing the efficacy of aerosolized pyrethrins with piperonyl butoxide, FDA noted that it reviewed two laboratory studies which were "supportive" of the efficacy of the aerosolized pediculicide, but "not adequate to establish general recognition of effectiveness." Data, FDA said, "are needed to demonstrate an appropriate time period for which an aerosolized pediculicide drug product must remain on the affected area in order to be effective before it is then washed off." FDA's safety conclusions on aerosolized pyrethrins with piperonyl butoxide are based on topical use for ten minutes. The agency noted that if efficacy studies demonstrate the need for longer treatment, "additional safety studies may be necessary." The TFM specifies that pediculicide products "consist of the combination of pyrethrins (0.17 to 0.33%) with piperonyl butoxide (2 to 4%) in a nonaerosol dosage form." Under the proposed rule, the products may carry the indication: "For the treatment of head, pubic (crab), and body lice." Proposed warnings for the OTC product class include: 1) "Use with caution on persons allergic to ragweed;" 2) "For extenal use only. Do not use near the eyes or permit contact with mucous membranes. If product gets into the eyes, immediately flush with water. Consult a doctor if infestation of eyebrows or eyelashes occurs;" and 3) "If skin irritation or infection is present or develops, discontinue use and consult a doctor."
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