Efficacy of the topical skin protectant in advanced development

A topical skin protectant (TSP) (ICD 2289) is being developed to protect se rvice members from exposure to chemical warfare agents (CWA). The TSP is de signed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clinical studie s, is a cream containing two chemically inert substances: perfluoroalkylpol yether and polytetrafluoroethylene. Animal data showed that the TSP was eff ective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by pre venting the development of erythema and edema. The insect repellent N,N-die thyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protect ion was sustained when DEET was removed with a dry gauze prior to TSP appli cation. The TSP was also effective against percutaneous exposure of nerve a gents-thickened (with 5% methyl methacrylamide) soman (TGD) and VX (O-ethyl -S-[2-(diisopropylamino)ethyl]methylphosphonothioate)- by reducing the mort ality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when BEET was applied prior to TSP applic ation. Because human efficacy studies using CWA cannot be conducted, the ef ficacy will be demonstrated by the level of protection against poison ivy ( urushiol) contact dermatitis in humans.