Skin deposition and penetration of trichlorocarbanilide

Studies are reported on the localization and quantitative distribution of 3,4,4'-trichloro[14C]carbanilide([14C]TCC) in guinea-pig and human skin, and on the percutaneous absorption of TCC following topical application to guinea pigs. [14C]TCC was applied to guinea-pig skin in various vehicles (conventional, superfatted, 10 percent non-soap detergent (NSD) and 30 percent NSD soap suspensions or in N,N-dimethylformamide [DMF]) and under various conditions (e.g. freshly prepared or equilibrated suspensions; single or multiple washes). Most of the amount of TCC remaining in the skin after rinsing was deposited on the skin surface and only relatively minute amounts actually penetrated through the epidermis into the dermis. Whereas conventional soap facilitated a greater deposition of TCC on the skin surface than NSD, the latter caused greater amounts of TCC to be deposited in the pilosebaceous system and lower dermis than conventional soap. The absence of TCC in the blood and tissues of guinea pigs given topical applications of TCC lends further support to the very low order of percutaneous absorption of TCC. The localisation of TCC followed a similar pattern in human skin as in guinea-pig skin, but the amount deposited was less and the rate of disappearance was more for human than for guinea-pig skin.