title: A novel encapsulation of N,N-diethyl-3-methylbenzamide (DEET) favorably modifies skin absorption while maintaining effective evaporation rates.
abstract: N,N-diethyl-3-methylbenzamide (DEET) is popular insect repellent which is considered safe and effective, yet is subject to considerable skin absorption. Skin absorption decreases effective repellency since less DEET is available for evaporation. We have investigated the extent to which DEET skin absorption can be reduced and evaporation sustained through encapsulation. DEET permeation through human skin in vitro was measured for an ethanolic solution standard and for two novel topical controlled-release formulations in which the DEET active material was temporarily sequestered within a permeable, charged-film microcapsule. Evaporation measurements were gathered using Tenax TA cartridges and a sampling pump drawing air over the skin. Three formulations were studied: a previously reported microcapsule formulation (Formulation A); a newly-developed microcapsule formulation (Formulation B); and a non-encapsulated ethanol control solution. Formulation B led to a 30% reduction in DEET permeation versus control. The two microcapsule DEET formulations exhibited 36-40% higher cumulative evaporation from the skin than did the control. The vapor trapping measurements in vitro show that Formulation B provided more than 48h of effective evaporation rate for repellency, while Formulation A provided less than 35h and the ethanol control less than 15h. This establishes a technical advantage for the controlled-release approach.
authors.affiliation: University of Cincinnati, James L. Winkle College of Pharmacy, P.O. Box 670004, Cincinnati, Ohio 45267-0004, USA. Karrji@mail.uc.edu
authors.forename: Jennifer I
authors.initials: JI
authors.lastname: Karr
authors.forename: Tycho J
authors.initials: TJ
authors.lastname: Speaker
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Kasting
mesh_terms: D003671:DEET / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism*; D000431:Ethanol / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007302:Insect Repellents / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism*; D012869:Skin Absorption; D014835:Volatilization
chemical_list: D007302:Insect Repellents; D003671:DEET; D000431:Ethanol